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The measurement of visual impairment in national surveys: a review of available data sources

Prepared for the Thomas Pocklington Trust

The measurement of visual impairment in national surveys:

a review of available data sources

Jo d’Ardenne, Matt Hall, Sally McManus

October 2011

Prepared for the Thomas Pocklington Trust

Contents

Acknowledgements......................................................................................................2

Executive summary .....................................................................2The Pocklington Trust..................................................................................................2Background..................................................................................................................2Aims............................................................................................................................. 2Methodology.................................................................................................................2Notes only:................................................................................................................... 2Results.........................................................................................................................2Discussion....................................................................................................................2Recommendations.......................................................................................................2

1 Background and approach.....................................................21.1 Background.................................................................................................................... 21.1.1 Estimates of the prevalence of visual impairment...........................................................21.1.2 Factors influencing estimates of visual impairment.........................................................21.1.3 Use of general population surveys in estimating prevalence..........................................21.1.4 Variation in the definition of visual impairment................................................................21.2 Aims of this survey review...........................................................................................21.3 Process of review..........................................................................................................21.4 Summary of methodological approach.......................................................................21.5 Consultation with experts.............................................................................................21.6 Report structure............................................................................................................2

2 Types of data collection..........................................................22.1 National surveys of the general population................................................................22.2 National surveys using non-random sampling...........................................................22.3 Regional surveys...........................................................................................................22.4 Surveys of people with visual impairment..................................................................22.5 Surveys of disabled people..........................................................................................22.6 Surveys of other population subgroups......................................................................22.7 Surveys with objective measures................................................................................22.8 Administrative data sources.........................................................................................22.9 Qualitative research with visually impaired people....................................................2

3 Methods....................................................................................23.1 Identification of surveys to include in the analysis....................................................23.1.1 Survey inclusion criteria..................................................................................................23.1.2 Eligible surveys not included in the analysis...................................................................23.1.3 Surveys included in the analysis.....................................................................................23.2 Analysis..........................................................................................................................23.2.1 Statistical approach........................................................................................................23.2.2 Weighting........................................................................................................................ 23.2.3 Missing data................................................................................................................... 2

4 Surveys.....................................................................................2

4.1 Health Survey for England (HSE).................................................................................24.1.1 Visual impairment questions asked................................................................................24.1.2 Long-standing illness code frame...................................................................................24.1.3 Visual impairment prevalence estimates........................................................................24.1.4 Methodological issues....................................................................................................24.1.5 Study contacts and further information...........................................................................24.2 Scottish Health Survey (SHeS).....................................................................................24.2.1 Visual impairment questions asked................................................................................24.2.2 Visual impairment prevalence estimates........................................................................24.2.3 Methodological issues....................................................................................................24.2.4 Study contacts and further information...........................................................................24.3 Welsh Health Survey (WHS) 2007................................................................................24.3.1 Visual impairment questions asked................................................................................24.3.2 Visual impairment prevalence estimates........................................................................24.3.3 Methodological issues....................................................................................................24.3.4 Study contacts and further information...........................................................................24.4 Adult Psychiatric Morbidity Survey (APMS) 2007.......................................................24.4.1 Visual impairment questions asked................................................................................24.4.2 Visual impairment prevalence estimates........................................................................24.4.3 Methodological issues....................................................................................................24.4.4 Study contact and further information.............................................................................24.5 English Longitudinal Study of Aging (ELSA) Wave 4.................................................24.5.1 Visual impairment questions asked................................................................................24.5.2 Visual impairment prevalence estimates........................................................................24.5.3 Methodological issues....................................................................................................24.5.4 Study contacts and further information...........................................................................24.6 Family and Children Survey (FACs) 2006-2007...........................................................24.6.1 Visual impairment questions asked................................................................................24.6.2 Visual impairment prevalence estimates........................................................................24.6.3 Methodological issues....................................................................................................24.6.4 Study contact and further information.............................................................................24.7 Family Resources Survey.............................................................................................24.7.1 Disability questions asked..............................................................................................24.8 FRS Disability Follow-up (1997)...................................................................................24.8.1 Visual impairment questions asked in Disability Follow-Up............................................24.8.2 Visual impairment prevalence estimates........................................................................24.8.3 Methodological issues....................................................................................................24.8.4 Study contact and further information.............................................................................24.9 Living in Wales Survey 2008.........................................................................................24.9.1 Visual impairment questions asked................................................................................24.9.2 Visual impairment prevalence estimates........................................................................24.9.3 Methodological issues....................................................................................................24.9.4 Study contact and further information.............................................................................24.10 Low Income Diet and Nutrition Survey 2005..............................................................24.10.1Visual impairment questions asked................................................................................24.10.2Visual impairment prevalence estimates........................................................................24.10.3Methodological issues....................................................................................................24.10.4Study contacts and further information...........................................................................2

4.11 National Diet and Nutrition Survey (NDNS) 2008-9....................................................24.11.1Visual impairment questions asked................................................................................24.11.2Visual impairment prevalence estimates........................................................................24.11.3Methodological issues....................................................................................................24.11.4Study contacts and further information...........................................................................24.12 Life Opportunities Survey (LOS) 2010........................................................................24.12.1Visual impairment questions asked................................................................................24.12.2Visual impairment prevalence estimates........................................................................24.12.3Methodological issues....................................................................................................24.12.4Study contacts and further information...........................................................................24.13 Understanding Society 2010/11...................................................................................24.13.1Visual impairment questions asked................................................................................24.13.2Visual impairment prevalence estimates........................................................................24.13.3Methodological issues....................................................................................................24.13.4Study contacts and further information...........................................................................2

5 Comparisons between surveys..............................................25.1 Types of measures identified.......................................................................................25.1.1 Questions on disability and health conditions.................................................................25.1.2 Questions on visual capability........................................................................................25.1.3 Questions on specific ocular conditions..........................................................................25.1.4 Questions on self-rated eyesight and ‘difficulty seeing’..................................................25.2 Inclusion and exclusion criteria...................................................................................25.2.1 Use of low vision aids (LVAs).........................................................................................25.2.2 Whether conditions are ‘limiting’.....................................................................................2

6 Conclusions.............................................................................2

Appendix A Summary of surveys..............................................2Summary table of reviewed surveys, sample and questions........................................2

Appendix B Project team...........................................................2Project team................................................................................................................. 2Project advisors............................................................................................................2

Appendix C Suggested further work.........................................2Summary...................................................................................................................... 2C1 Extend the scope of the review...........................................................................2C2 Cognitive development work with visually impaired people.................................2C4 and C5 Developing the HSE coding of visual impairment......................................2C6 and C7 Secondary analyses of HSE and other survey datasets: trends, subgroups and social inclusion......................................................................................................2

Notes and References..............................................................................................................2

TablesTable 4:1 Prevalence of visual impairment, by age group (HSE 2007)......................................................2Table 4:2 Prevalence of visual impairment, by sex (HSE 2007)................................................................2Table 4:3 Prevalence of visual impairment, by age group (SHeS 2008)....................................................2Table 4:4 Prevalence of visual impairment, by sex (SHeS 2008)..............................................................2Table 4:5 Prevalence of self-reported difficulties in seeing the face of someone across a room, by age group

(WHS) 2Table 4:6 Prevalence of self-reported difficulties in seeing the face of someone across a room, by sex (WHS)

2Table 4:7 Prevalence of self-reported visual impairment at Llticde, by age group (WHS).........................2Table 4:8 Prevalence of self-reported visual impairment at Llticde, by sex (WHS)....................................2Table 4:9 Prevalence of self-reported cataracts/eyesight problems in past 12 months, by age group (APMS)

2Table 4:10 Prevalence of self-reported cataracts/eyesight problems in past 12 months, by sex (APMS).2Table 4:9 Prevalence of self-reported ocular conditions, by age group (ELSA)........................................2Table 4:12 Prevalence of self-reported ocular conditions, by sex (ELSA).................................................2Table 4:13 Prevalence of self-rated quality of eyesight, by age group (ELSA)..........................................2Table 4:14 Prevalence of self-rated quality of eyesight, by sex (ELSA).....................................................2Table 4:15 Prevalence of self-rated difficulty in seeing, by age group (FACS)..........................................2Table 4:16 Prevalence of self-rated difficulty in seeing, by sex (FACS).....................................................2Table 4:15 Prevalence of ‘difficulties with sight’ i.e. uses glasses or contacts by age...............................2Table 4:16 Prevalence of ‘difficulties with sight’ i.e. uses glasses or contacts by sex...............................2Table 4:15 LOS % of respondents reporting difficulties in seeing things up close and at distances by age2Table 4:16 LOS % of respondents reporting difficulties in seeing things up close and at distances by sex2Table 4:15 Prevalence of visual impairment by age using LOS definition.................................................2Table 4:16 Prevalence of visual impairment by sex using LOS definition..................................................2Table 4:15 Prevalence of respondents reporting difficulties with sight by age group in Understanding Society

2Table 4:16 Prevalence of Prevalence of respondents reporting difficulties with sight by sex in Understanding

Society 2Table 5:1 Visual impairment measures among older people, by survey and age group...........................2Table 5:2 Visual impairment measures among younger people, by survey and age groupError! Bookmark

not defined.

FiguresFigure 4:1 HSE 2007 question on long-standing illness, disability or infirmity..........................................2Figure 4:1 Long-standing illness code frame.............................................................................................2Figure 4:3 Descriptions of codes related to visual impairment...................................................................2Figure 4:4 SHeS 2008 ‘long-standing physical or mental condition or disability’ questions.......................2Figure 4:3 WHS 2007 question on eyesight quality...................................................................................2Figure 4:4 WHS 2007 questions on health conditions and disabilities.......................................................2Figure 4:5 Comparisons between ‘See’ and ‘LLticde’ by sex (WHS).........................................................2Figure 4:8 APMS 2007 Questions on general health.................................................................................2Figure 4:9 ELSA questions on ocular conditions........................................................................................2Figure 4:10 ELSA question on self-rated eyesight.....................................................................................2Figure 4:11 Self-rated quality of eyesight, by whether have a self-reported ocular condition (ELSA)......2Figure 4:12 FACS question on long-standing illness or disability..............................................................2Figure 4:13 Comparing prevalence of visual impairments reported in HSE, SHeS and FACs..................2Figure 4:12 FRS questions on long-standing illness or disability...............................................................2Figure 4:13 FRS Disability Follow-up questions on health conditions........................................................2Figure 4:13 FRS Disability Follow-up questions on visual capacity...........................................................2Figure 4:14 Living in Wales questions on long-term illness or disability....................................................2Figure 4:15 Living in Wales questions on type of disability or impairment.................................................2Figure 4:16 LIDNS questions on long-standing illness, disability or infirmity.............................................2Figure 4:16 LOS questions on sight...........................................................................................................2Figure 4:16 LOS questions on long-term impairments and disability.........................................................2Figure 4:17 Understanding Society questions............................................................................................2Figure 5:1 Phrasing of questions on disability.....................................................................................2Figure 5:1 Prevalence of visual impairment, by survey and sex................Error! Bookmark not defined.Figure 5:2 Prevalence of visual impairment, by survey and age group......................................................2

Acknowledgements

We would first like to thank the Thomas Pocklington Trust and its trustees for guidance on shaping this review and for the financial support that made it possible. In particular, we thank Dr Angela McCullagh, Katrina Harrington and Sarah Buchanan for their advice and patience.

We would also like to thank the many people who have contributed to this project in terms of identifying relevant resources for inclusion, providing detail on the methodology of specific surveys, and advising on the clinical aspects of conditions that can cause sight loss. We are particularly indebted to the staff at the UK Data Archive for help with accessing the datasets.

Furthermore, we would like to acknowledge the time and contribution of the many thousands of respondents whose generous participation continues to make social surveys possible, and the professionalism and dedication of the interviewers and the research nurses who collect the survey data in field.

Jo d’Ardenne, Matt Hall, Sally McManus

Executive summary

The Pocklington TrustThis review was funded by a research grant from the The Pocklington Trust. The Trust supports social and public health research that identifies practical ways in which the lives of people with sight loss can be improved. The report describes what national general population survey data are available that allow us to compare the situation of people with visual impairment with that of the rest pf the population. The objective is to improve the measurement of visual impairment in British national survey research.

BackgroundRegistration rates and health service use statistics represent a minority of people affected by sight loss. Population prevalence estimates vary depending on the definitions applied and the data collection methodology used. A range of different indicators of visual impairment are used on national surveys in Britain. There have been no ‘gold standard’ questions for capturing the presences of visual impairment in general population survey research.

Aims Identify what questions about the presence of visual impairment are

currently being used in national surveys of the general population. Consider what these questions capture (for example, reference to low

vision aids; use of filter questions; mode of administration; location in questionnaire; prevalence estimates of visual impairment generated; how rates compare across surveys by sex and age).

Engage with a range of clinical and social researchers and with government social research and its agencies, on evaluating current approaches to assessing visual impairment on general population surveys.

REVIEW OF VISUAL IMPAIRMENT SURVEY QUESTIONS 1

NATCEN, 14/09/11,

The executive summary will be produced after comments are received on the main report.

Methodology A review was undertaken to identify relevant surveys using search

engines and contacts. Inclusion criteria were applied to prioritise studies for the analysis.

Datasets were obtained from the UK Data Archive or direct from researchers. For each survey, the sample profile was described and the questions and the format of their administration were documented.

SPSS was used to manage the data: the relevant variables were identified, derived variables produced, and prevalence rates generated and presented by age and sex.

The draft report was circulated to various experts and commissioners in the field for comment and a roundtable discussion held to refine the report’s content and recommendations. (underway)

Notes only:

Results

Discussion

Recommendations Harmonised disability questions group. Sample Survey topic Interviewer and research nurse training Survey method Question location – Health section? Disability section? Socio-

demographics? Question format – prompted, unprompted, observed, objective. Filter questions Use of low vision aids, impact on functioning Code frames Aggregating categories: ‘sensory impairments’ Survey reporting Archiving and documentation.



1 Background and approach

1.1 Background

1.1.1 Estimates of the prevalence of visual impairmentThere are various estimates of the size of the population with visual

impairmenti: a widely cited figure is that sight loss affects the everyday

lives of up to two million people in the UK.ii Access Economics estimated

that in 2008 there were 1.8 million people in the UK with sight loss (1.6

million who were partially sighted and 0.2 million blind people).iii

Our changing demographics – including in terms of age, ethnicity and

obesity – are impacting on trends in the prevalence of visual impairment.iv

The majority of affected people are aged 75 and over,v although it has also

been estimated that 80,000 people of working age are living with sight loss

in the UK.vi The overall visual-impaired population has been projected to

rise by a quarter over the next 30 years,vii and to more than double by

2050.viii In England, about 310,000 people are registered with Councils with

Adult Social Services Responsibilities (CASSRs) as sight impaired

(partially sighted) or as severely sight impaired (blind).ix,x Registration rates

therefore represent an underestimate of the wider number of people who

may be considered to have a visual impairment.

1.1.2 Factors influencing estimates of visual impairmentPrevalence estimates vary according to what is measured (for example,

conditions or symptoms), how it is defined and captured, and who is asked.

Visual impairment is not only multi-categorical in the symptoms manifested

(for example, tunnel vision, blurred vision, reduced contrast), but also

multi-dimensional in encompassing a spectrum of severity within each


category. Self-evaluation of symptoms and severity are problematic, as

they depend on expectations and recall as well as being sensitive to other

sources of reporting bias.

While some thresholds of severity have been agreed for particular contexts

(for example, to qualify for registration), there are no ‘gold standard’

questions for operationalising such thresholds in survey research. The

work of Tait et al. has drawn together key studies that have contained good

quality ophthalmic assessments, mostly among older people. However,

most national, general population social surveys do not have the capacity

(in financial or time resources) to include such assessments. Recently, the

Office for National Statistics (ONS) issued a suite of harmonised questions

recommended for the measurement of disability and impairment on

government social surveys. These will be considered as part of this review.

1.1.3 Use of general population surveys in estimating prevalence

To examine the prevalence of impaired vision, and its comorbidity and

correlates, surveys are uniquely well placed. They collect a wealth of rich

and publicly available data and are a cost effective resource that can be

better utilised. In particular, general population surveys enable examination

of treatment and registration rates among all people with visual

impairment, as samples also include those who are not in contact with

support and services. General population survey data are essential if the

circumstances of visually impaired people are to be compared with those

of the population as a whole. Without such data, social and economic

inequalities can not be fully documented.

Major government and research council funded studies ask a range of core

socio-demographic questions, irrespective of the focus of the

questionnaire. These often use agreed government harmonised question


wordings to enable cross study comparisons.xi General health, and to a

lesser extent functional impairment, have been included in a number of

these. However, visual impairment has not been prioritised. We can

hypothesis why this might be:

it is regarded as of specialist (rather than generalist) interest;

it is not recognised as widespread;

it is subject to a wider neglect of issues that disproportionately affect

older people; and finally,

because of the lack of good quality usable questions suitable for lay

survey administration (see Tate et al.xii).

In the current economic climate, which has hit social research hard, these

obstacles are even harder to overcome.

It should be noted that it is not an aim of this review to estimate the

prevalence of visual impairment in the population, rather to identify what

survey questions are currently in use and to examine the impact of

question and survey method on the proportion and characteristics of the

population with visual impairment that is identified.

1.1.4 Variation in the definition of visual impairmentThe current approaches to assessing whether or not survey respondents

have a visual impairment are inconsistent and may often be inaccurate.

Approaches in both clinical contexts and population-based studies have

used varying methods and thresholds in defining and measuring sight

related problems. Definitions have typically focused on specific medical

eye conditions, the presence of particular symptoms, functional aspects of

what the person can and cannot see in different contexts, and on

subjective assessments of quality of eyesight. There is no ‘true’ or absolute

prevalence of visual impairment. Rates and associations depend on the

definitions used and in terms of what aspects of visual impairment are


considered and what severity thresholds are considered relevant for being

‘visually impaired’.

1.2 Aims of this survey reviewThe aims of this report are to:

Review what questions capturing any aspect of visual impairment

are currently being used; with what populations; and where.

Describe what these questions measure; what allowance is made

for use of low vision aids; what prevalence estimates of visual

impairment they generate; and how the rates compare by sex and

age group.

Engage with a range of clinical and social researchers and with

government social research and its agencies on evaluating current

approaches to assessing visual impairment on general population

surveys.

We hope that through this review and subsequent discussions to:

Review the data already collected.

Raise the profile of visual impairment measurement among social

researchers and survey commissioners to inform future data

collection.

Identify cost effective secondary analyses or methodological

development work that could be done to situate the circumstances

of visually impaired people in the context of the wider population.

1.3 Process of review

Stage 1: Initial consultation

Initial exchange with experts (research, clinical and policy).

Stage 2: Review population based surveys including a measure of visual

impairment


Identify national general population surveys.

Obtain data sets and generate prevalence estimates.

Review methodology.

Describe potential secondary analyses.

To come:

Stage 3: Discussions

Present initial review findings.

Stage 4: Finalise review report

Circulate for further iterations of input and comment.

1.4 Summary of methodological approachA search of datasets held by the UK Data Archive was undertaken. Papers

and reports accessed through Athens, Medline, and Social Care Online

were scanned for mention of relevant British-based national surveys. We

also used word-of-mouth suggestions from other researchers, in particular

to identify surveys where the visual impairment data had not (yet) been

written up in survey reports or as academic papers.

SPSS was used to generate prevalence estimates of different definitions of

visual impairment from all the relevant national surveys for which we were

able to obtain data. This used the relevant weighting variables, where

these were archived on the dataset. The rates were national (representing

England, Scotland or Wales) and produced by age and sex, to facilitate

comparison across surveys covering different age ranges.

1.5 Consultation with experts We would like to acknowledge the (on-going) input from a range of different professionals. These include:


NATCEN, 13/09/11,

Those with an asterix* below have been identified as people/ organisations we would like to engage with further. Other suggestions welcome.

Charities and campaign organisations Femi Nzegwu, British Red Cross

Sarah Buchanan, Thomas Pocklington Trust

Others, such as: Vision 2020 UK, the Royal National Institute of

Blind People (RNIB), Action for Blind People (ABP), the Eyecare

Trust, Fight for Sight, others we could invite comment from? (we

would like here to acknowledge the input of anyone at the RNIB

meeting on 21st September, if they are happy with that).*

Survey directors and managers Joanna Bulman and Ian O’Sullivan, Life Opportunities Survey (LOS),

ONS

Rachel Craig, Health Survey for England (HSE) director, NatCen

Kate Taylor, English Longitudinal Survey of Aging (ELSA) director,

NatCen

Katharine Sadler, Welsh Health Survey (WHS) director, NatCen

Catherine Bromley, Scottish Health Survey (SHeS) director,

ScotCen

Beverley Bates, National Diet and Nutrition Survey (NDNS) director,

NatCen

Joanne Maher, Family Resources Survey (FRS), NatCen

Clare Tait, Family and Children Survey (FACS), NatCen

Ruth Smith and Aleks Collingwod, Better Design Survey, NatCen

Richard Boreham, Understanding Society (US), NatCen

Academics Sam Waller, Engineering Design Centre, Cambridge University

James Nazroo, Director of the Centre for Census and Survey

Research, University of Manchester

Howard Meltzer, Professor of disability and mental health, University

of Leicester

Janet Robertson, Lancaster University


Ian Bruce, City University*

Graeme Douglas, University of Birmingham*

Geoff Cook, Reading University*

Jude Robinson, Liverpool University*

Bruce Evans, Institute of Optometry*

Jennifer Evans, Astrid Fletcher, Emily Grundy, LSHTM*

Rosemary Tate, University of Sussex*

Clinicians Royal College of Ophthalmologists*

Moorfields Eye Hospital NHS Foundation Trust*

The College of Optometrists*

Government departments and agencies Bethan Thomas, Statistical Head of Surveys and International

Statistics, NHS Information Centre for health and social care

Martin Farmer, Office for Disability Issues (ODI), Department for

Work Pensions (DWP)

Andrew Nocon, Research Manager, Equality and Human Rights

Commission (EHRC)

Department of Health (DH)*

1.6 Report structureChapter 2 gives an overview of the range of types of data collection that provide insight into the prevalence and profile of the visually impaired population in Britain.

Chapter 3 describes the methods used in doing this review and lists the surveys screened in as eligible for the analysis.

Chapter 4 reviews each eligible survey in terms of its visual impairment questions and the prevalence estimates that each question generates.


Chapter 5 makes comparisons between the surveys.

Chapter 6 draws out overarching conclusions.

Chapter 7 lists recommendations for improving the future measurement of visual impairment in national general population surveys.

Appendices outline: the project team; further work that could be done using existing, publicly available survey datasets (in particular HSE); and summarises the reviewed surveys and questions.


1 Types of data collectionThere is a range of types of data collection, and many include some

information on visual impairment. To provide context for this review of

national surveys of the general population, some the other types of data

collection are briefly discussed in this chapter:

National surveys of the general population

National surveys using non-random sampling

Regional surveys

Surveys of people with visual impairment

Surveys of disabled people

Surveys of other subgroups of the population

Surveys using objectives measures

Administrative data sources

Qualitative studies

In this chapter, a brief discussion of the strengths and weaknesses of using

each of these approaches for estimating the prevalence and describing the

profile of people with visual impairment is given. Strengths and

weaknesses tend to relate either to how representative the sample is or to

the validity of the information on visual impairment collected.

The main aim of this review is to consider the impact of survey questions

on the prevalence and profile of visual impairment generated. The

remainder of the report therefore focuses only on national surveys that

include a random sample of the general population (or an age-cohort of the

general population, for example, everyone born in a particular year).


1.7 National surveys of the general populationA benefit of using national surveys of the general population is that they

are sufficiently representative and large to yield reliable estimates of

prevalence. They also provide excellent data on individuals’

circumstances, ideal for describing the characteristics of the visually

impaired population and being able to compare them with people without

visual impairment. Such data are already collected and publicly available,

and so efficient for further analysis.

Limitations of using national surveys of the general population include the

fact that although the overall sample is usually large, because a minority of

people are visually impaired the number of people surveyed with visual

impairment might be small. Participation in surveys can be subject to

biases associated with the presence of visual impairment, with visually

impaired people less likely to take part and less likely to be sampled in the

first place (given that communal residential settings are generally

excluded). The use of showcard prompts and self-completion booklets in

interviews compounds this exclusion. Furthermore, general population

surveys tend to rely on self-report rather than objective measures, raising

concerns about the validity of the information captured. Questions are also

filtered and phrased in such a way that can contribute to underreporting or

overreporting of visual impairment.

These issues will be explored further in the rest of this report.

1.8 National surveys using non-random sampling

The surveys reviewed in this report all use random probability samples.

These are not simple random samples - which in practice are almost

impossible to achieve at a national level, as some clustering is required for

fieldwork efficacy - but where everyone in the eligible population had a

known and quantifiable chance of selection. Convenience samples, often


using quotas, are not included because while they can collect valid

information about the relationships between variables, they tend not to be

representative of the wider population. The people most likely to take part

in quota sample surveys are those who are easy to get hold of: people who

do not work (including for health or impairment reasons) or who work from

home. It is possible that there are commercially sponsored market

research surveys that have collected data on visual impairment. However,

the data from these tend not to be publicly documented or archived for

further analysis.

1.9 Regional surveys

Some of the key surveys focusing specifically on eye health have focused

on a single city; Copenhagenxiii, Melbournexiv, Beaver Damxv, Baltimore,

Leicestershire and North Londonxvi. There can be efficiency gains to

focusing resources and trained personnel in one geographic area, and

increasingly data are needed at lower levels for the monitoring and

planning of social and other resources. However, there can be

generalizability concerns in using data from one region to estimate rates

nationally, given regional variations in population characteristics and

environment.

Case study: The Copenhagen City Eye Study.xvii

This study was based on the third Copenhagen City Heart Study (CCHS

III). Participants who reported visual impairment or blindness or had

difficulty reading newspaper type and used prescribed eye medications

were contacted from 1999 through 2000 and asked to complete a

standardised interview concerning their ophthalmologic history. Verification

of objective ophthalmologic data was done with a questionnaire.

Prevalence rates of visual impairment and blindness were 0.7% and 0.2%

for the Copenhagen adult population. For people aged 20 to 64 years,


myopia-related retinal disorders, diabetic retinopathy, optic neuropathy,

and retinitis pigmentosa were the most common causes of impaired vision.

For older people (aged 65 to 84), cataract was the most common cause of

visual impairment, whereas age-related macular degeneration was the

major cause of blindness.

1.10 Surveys of people with visual impairment

The general population surveys in this review cover a very wide range of

topics, so the coverage of visual impairment tends to be limited to a few

questions. Surveys specifically of people with visual impairment will

naturally be more sight loss focused and relevant in their coverage. The

sample of people with a visual impairment may well also be larger.

However, drawbacks include how representative of all people with a visual

impairment the survey sample is, the lack of a control sample for making

comparisons, and the inability to estimate the prevalence of visual

impairment (unless the sample was obtained by screening the general

population).

Case study: Network 1000 Network 1000 is an innovative and ambitious project that has brought

together a panel of 1000 visually impaired people from across the UK.xviii Its

main aim is to survey the changing needs and circumstances of visually

impaired people. In 2004, Vision 2020 UK and the Visual Impairment

Centre for Teaching and Research (VICTAR) at the University of

Birmingham were commissioned by the Big Lottery Fund to carry out

phase one of the broader Network 1000 project. Network 1000 phase two

started in 2007 and has been funded by the Thomas Pocklington Trust,

RNIB and GDBA. Phase two aims to further analyse the data gathered in

Phase one as well as maintain the Network 1000 sample.xix


The Network 1000 panel is drawn from the registers of blind and partially

sighted people held by 20 social services departments. The sample is

likely to be a good reflection of the registered population. Although the

response rate achieved was very low compared with a general population

survey (about 17%), great care has been taken with the sampling and

weighting strategies to take account of this. However, it will not be

representative of people with a less severe impairment or of people who

are not registered with social services. The panel have reported on a range

of different policy topics.xx

Study contact and further information

VICTAR - Visual Impairment Centre for Teaching and Research -

University of Birmingham ([email protected])

http://www.vision2020uk.org.uk/library.asp?section=000100050005

1.11 Surveys of disabled peopleThere have been a number of surveys conducted with a sample only of

disabled people.xxi While these can yield useful information about people

with a visual impairment, there are major limitations to using such a data

source:

Some of the samples were generated in such a way that a population

level prevalence of each impairment type cannot be generated. The

proportion of disabled people with a visual impairment is sometimes

presented rather than the proportion of people in general population

who have visual impairment (for example, see the GFK study below).

There may be no general population group to make comparisons with.

The screening tools used to identify people to include in the survey

sample tend not to explicitly mention visual impairment. There is

therefore a risk that potential respondents do not regard visual

impairment as an eligible ‘disability’, and its prevalence will be

undercounted.


http://www.vision2020uk.org.uk/library.asp?section=000100050005

mailto:[email protected]

The general shift in disability research away from medical models of

disability means that diagnostic information about conditions,

symptoms and the causes or nature of impairments is sometimes not

collected.

The parallel shift towards a more social model of disability places the

emphasis on whether or not someone experiences barriers in their

environment because of an impairment. Someone with visual

impairment who is not ‘disabled’ by their environment is technically

out of the scope of a survey of disabled people under this conceptual

model.

As with other types of survey, there is a limit on the number of

impairments that can be recorded. Furthermore, on a survey of

disabled people the risk is greater that other impairments will be

recorded as the primary one. Subsequent coding may give less

emphasis to ‘secondary’ impairments or to symptoms regarded as

secondary to another primary condition.

Many of these limitations are successfully addressed in the Life

Opportunities Survey (LOS, see Section 4.12). Although LOS is about

disability, it is also a national survey with a full general population sample.

Case study: Experiences and Expectations of Disabled PeopleIn 2006, the Office for Disability Issues (ODI) commissioned a programme

of research to explore the lives of disabled people in Britain. The research

aimed to address information gaps on how disabled people’s lives have

changed and providing detail on their current experiences.xxii The survey

found one in ten (12%) disabled people reported a ‘visual impairment’,

ranging from 7% of 16 to 34 year olds, up to 20% of disabled people aged

75 or over.xxiii The survey was useful for making comparisons between

impairment groups, for example people with visual impairment (61%) were

less likely than other disabled people to feel that their residential property


was suitable for their needs. They were also more likely than people with

other impairments to report difficulties with public transport.xxiv

The survey research team describe how consultation with a reference

group of disabled people shifted the survey sampling approach towards a

more social model:

“There was consensus among interviewees that the draft screener [used to

identify eligible respondents] was too heavily based on the medical model of

disability and that the questioning around people’s conditions was very long and

clinical, and ultimately unnecessary. In response this was replaced with a shorter

and simpler version, which would enable people to self-identify which broad

group (physical or visual impairment etc.) they felt best described their

impairment. Similar comments were made about the language suggested in

some of the survey questions being too heavily based on the medical model,

which were amended to reflect the social model better.”

As a consequence of taking a social model approach, the survey questions

moved away from the collection of clinical diagnoses of conditions.

Study contact and further information

Vicki Wright, NatCen

http://odi.dwp.gov.uk/docs/res/eedp/eedp-exec-summary.pdf

1.12 Surveys of other population subgroups

There are a number of surveys that draw their samples from specific

sampling frames or select only members of particular subgroups. Surveys

of older people, such as the English Longitudinal Study of Aging (ELSA),

have tended to include more questions about visual impairment because of

the high proportion of older people who are affected. Other relevant

surveys have been of civil servants (Whitehall II), parents (Families and

Children Survey), older people living in communal settings (HSE 2000),


http://odi.dwp.gov.uk/docs/res/eedp/eedp-exec-summary.pdf

unemployed people (Evaluation of the New Deal for Disabled People), and

people recruited through contact with a particular service, treatment, clinic

or due to registration.xxv

These surveys share many of the same benefits and limitations as outlined

above. In particular, while they can provide rich data on a particular

subgroup, they are not well placed for creating prevalence estimates of the

visually impaired population or for comparing visually impaired people with

the wider population.

Case study: Evaluation of the New Deal for Disabled PeopleThere has been an extensive programme of evaluation of the New Deal for

Disabled People. This included asking disabled people on Incapacity

Benefit (now Employment Support Allowance) about the nature of their

impairment. One interesting finding was that while 2% of the sample

reported visual problems as their main impairment, a further 4% reported it

as a secondary impairment. For the other impairment types asked about,

generally people were more likely to report them as primary than

secondary.

Study contacts and further information Martin Wood, NatCen

http://research.dwp.gov.uk/asd/asd5/report_abstracts/rr_abstracts/

rra_260.asp

1.13 Surveys with objective measures The surveys discussed so far (except for the regional surveys described in

Section 2.3) tend to rely on self-report measures of visual difficulties or

known diagnoses. The validity of both these approaches has been

questioned. In The prevalence of visual impairment in the UK: A review of

the literature, Tate et al. describe the UK based studies (mostly regional)

that have included visual acuity measures.xxvi These include the very large


http://research.dwp.gov.uk/asd/asd5/report_abstracts/rr_abstracts/rra_260.asp

http://research.dwp.gov.uk/asd/asd5/report_abstracts/rr_abstracts/rra_260.asp

Medical Research Council (MRC) Assessment Trial, which focused on

older people.xxvii

There are some innovative developments going on in survey research,

which seek to allow more objective assessments and tests to be

administered on national surveys by lay-interviewers. Some of these have

not progressed to a main stage of data collection, either due to timing or

funding, but one large pilot study is described below.

Case study: The Capability Better Design Survey This large-scale pilot survey assessed the feasibility of doing a large

national survey to produce data on the sensory, motor and cognitive

capabilities of a representative sample of adults in the UK.xxviii The aim was

to provide data for product designers on how to design products which can

be used by as much of the population as possible. It was carried out by the

University of Cambridge and NatCen, and funded by the Engineering and

Physical Sciences Research Council (EPSRC) in response to a grant

application. The project was called “i~design 3: extending active living

through more effective inclusive design”. A nationally representative

sample of 362 adults was interviewed for this pilot study.

One of the study objectives was to develop survey methods to assess the

threshold levels of letter size and contrast for product features that can be

easily detected. To test near vision, show cards were used that consisted

of twelve rows of letters. These tested a rage of different contrast levels.

For distance vision, show cards had to be located on a respondent’s shelf

and tape measures used to assess distance. Respondents wore any low

vision aids that they usually used for most of the day or for distance vision

or close work. The pilot study tested the feasibility of developing protocols

for objective assessments that lay-interviewers could administer in

people’s own homes.


Table 2.1 shows how interviewers rated the performance of the objective

tests administered on this pilot study.


Table 2.1 Interviewer feedback on the performance of the tests used in the Better Design Survey pilot

Base: All interviewers

Interviewer rating of test performance

Type of test Very well Quite wellNot very

wellNot at all

wellNot

answeredN N N N N

Vision 4 12 2 0 1Hearing 16 3 0 0 0Moberg pick up 9 10 0 0 0Grip 4 13 2 0 0Using mobile phone 11 7 0 0 1MP3 player dexterity 14 5 0 0 0Arm raises 12 7 0 0 0Cognitive 12 7 0 0 0Interface style 7 10 2 0 0Finger width 12 7 0 0 0

The vision tests were not considered to be as successful as many of the

other tests piloted. Reasons given by interviewers for this included:

Problems with light quality in people’s homes

Difficulty finding a three metre unobstructed view for the display of

eye test showcards.

Study contacts and further informationAleks Collingwood and Ruth Smith, NatCen

http://www.natcen.ac.uk/study/educational-attainment-of-blind-and-

partially-sighted-pupils

1.14 Administrative data sources

National administrative data sources can provide some very powerful

insights into visual impairment, not least because they provide a census of

a particular population subgroup and so have an enormous sample. The


http://www.natcen.ac.uk/study/educational-attainment-of-blind-and-partially-sighted-pupils


future potential of administrative data sources is likely to increase greatly

with improved techniques for data linkage, including linking survey data

with databases such as Hospital Episode Statistics.

Registration rates, however, are known to undercount the prevalence of

visually impairment in the population because people with less severe

impairments (but who may still be of interest) will be less likely to be

included, and some people with severe impairments may remain

unregistered. The groups excluded from registration are different in

characteristics compared with the included groups, leading to the sample

being biased. Administrative data sources also tend to be weak in terms of

the availability of contextual data about individuals and so have limited use

for profiling the visually impaired population or comparing them with the

wider population.

Examples of two types of administrative data sources are given below, plus

a case study showing the type of further analysis that can be done using

publicly available administrative data.

Registration as blind or partially sighted Every three years, The NHS Information Centre collates council

information on the numbers of people registered as Blind or Partially

Sighted.xxix The next update on this is due to publish in October 2011.

Councils are provided with guidance and a template for the data

collection.xxx

Data on NHS sight testsThe NHS Information Centre Dental and Eye Care Team collate

information on the number of NHS sight tests, by patient eligibility. One of

these eligibilities is for patients registered blind or partially sighted.xxxi

Further information, including details of data collection, is available in the

NHS Information Centre Guide to Eye Care publications document.xxxii


Case study: Educational attainment of blind and partially sighted pupilsThe RNIB commissioned NatCen to report on the educational attainment of

blind and partially sighted secondary school pupils in England, Wales,

Scotland and Northern Ireland. Pupil information held in the National Pupil

Databases for England and Wales, the Northern Ireland School Leavers

Survey and the Scottish Annual Pupil Census were used. Regression

analysis was undertaken to look at the effect of special educational needs,

and specifically visual impairment, on secondary school attainment. In all

four countries, pupils with visual impairment performed less well than

pupils without SEN - but generally better than pupils who had other SEN.

The study highlighted problems with the Government's published figures

on educational attainment of pupils with Special Educational Needs (SEN).

Government statistics are based on the pupil's primary SEN. However, this

study found that a major factor affecting the GCSE results of blind and

partially sighted pupils was whether or not they also had other SEN not

related to their vision.

Study contacts and further informationJenny Chanfreau and Andreas Cebulla, NatCen

http://www.natcen.ac.uk/study/educational-attainment-of-blind-and-

partially-sighted-pupils

1.15 Qualitative research with visually impaired peopleQualitative research can provide rich detail on the range and nature of

experiences among people with visual impairment, and there have been a

number of such studies. Findings from qualitative interviews can inform the

development of inclusive survey research methodologies. For qualitative

research a sample is selected in such a way as to represent a range of

relevant characteristics. It does not seek to quantify or to be

representative.




Case study: The opinions of people with sight loss on visual impairment researchThis piece of qualitative research, funded by the Thomas Pocklington

Trust, informs the format that survey and other research that includes

people with visual impairment should take.xxxiii Participants identified four

processes that should be attended to when planning and carrying out

research:

Research aims should be practical and useful for people with sight loss

Research methods should use a broad range of approaches to asking questions

Dissemination should offer a wide range of media, and People with sight loss should be included wherever and whenever

possible.


2 Methods

1.16 Identification of surveys to include in the analysisA search of datasets held by the UK Data Archive was undertaken. Papers

about visual impairment accessed through Athens, Medline, and Social

Care Online were scanned for mention of relevant British-based surveys.

We also used suggestions from researchers, in particular to identify

surveys where the visual impairment data has not (yet) been written up in

survey reports or as academic papers (as was often the case).

1.16.1 Survey inclusion criteriaThe inclusion criteria specified that to be eligible for this review, surveys

had to:

Cover a national British population (England, Scotland, Wales, or

Great Britain).

Use a general population sample (rather than be of a subgroup).

Have been conducted in the last decade (fieldwork since 2001).

In the case of repeated surveys (where data were available from

multiple waves in a survey series) priority was given to data from

2007-2009. A few surveys archived were from 2010 or 2011

(although not many due to the delay between survey fieldwork and

the archiving of final outputs). Waves of data collection closest to

2007/2008 were prioritised where available to ensure greater

comparability across the largest number of datasets. If data available

preceded 2007 the most recent dataset available was selected.

Respondents selected through random probability sampling.

The sample included adult respondents (for example, age 16 or

over).


The dataset was accessible (held on the UK Data Archive or

available directly from the survey researchers).

Survey documentation was available (archived material provided

sufficient details of the questionnaire administration, question

wording and coding instructions, where applicable).

At least one question in the archived data addressed type of health

condition, disability, impairment, or included the words ‘sight’, ‘see’,

‘vision’ or ‘visual’ in a relevant capacity.

These criteria were used as guidelines; the authors erred on being

inclusive where a survey looked valuable to the review. Reviewed surveys

include some conducted more than a decade ago or are of a population

subgroup.

1.16.2 Eligible surveys not included in the analysis

A number of surveys were identified as potentially eligible, but were not

included in the final analysis. These were the:

ONS Omnibus / Integrated Household Survey (2008)

ONS Omnibus: RNIB disability module (1998)

Labour Force Survey (LFS 2008) / Annual Population Survey (APS)

British Cohort Studies (BCS70 and 1946 National Birth Cohort)

The key reason for a survey being excluded from the review related to data

access:

1. Data from whole relevant questionnaire module not in the public data

archive.

2. Only ‘top level’ data from the relevant questionnaire module was

archived (variables on whether respondents had a health condition

were included, but variables about the type of health condition were

not included in the archived dataset).

3. Unexplained and significant ‘missing data’ on variables of interest.


The reasons that each study was excluded are detailed below.

ONS Omnibus / Integrated Household Survey (IHS 2008)The ONS Omnibus (now part of the large Integrated Household Survey,

IHS) regularly runs a module on disability on behalf of the Department of

Work and Pensions. Although data are publicly available, this particular

module was excluded from the dataset in the UK Data Archive.xxxiv

ONS Omnibus: RNIB disability module (1998)The RNIB ran a module of questions on vision in the 1998 ONS Omnibus.

Although this survey is out of scope because it was conducted more than a

decade ago, attempts were made to locate it due to its particular

relevance. Although data from the ONS Omnibus are publicly available,

data from this particular module could not be located in the UK Data

Archive. In addition to the data being unavailable, the original

questionnaires were not documented.

Annual Population Survey (APS) / Labour Force Survey (LFS)

The Annual Population Survey (APS) combines data from the Labour

Force Survey (LFS) and the English, Welsh and Scottish LFS boosts. It

does contain information on health conditions that limit daily activities.

However, the relevant variable on eyesight was not included in the

archived dataset for 2008. It is one of a number of variables have been

removed from the dataset prior to public archive as part of series of steps

to prevent risk of disclosure of respondent identity.

The Birth Cohort StudiesThe British birth cohort studies have included detailed questions on types

of impairment. The surveys are longitudinal, having followed a cohort of

people over many years, and so are well placed to look at predictors and

the impact of visual impairment. Data from the cohort surveys tend not to

be archived in the UK Data Archive. Access can be arranged directly with


the survey teams for legitimate research purposes; there tends to be a

small fee associated with this to cover the costs of data management and

advice. This was not pursued, however, as the cohort samples tend to be

of a subgroup of the population (for example, people born in a particular

year) and therefore not eligible for inclusion as they are not representative

of the general population as a whole.

1.16.3 Surveys included in the analysisTwelve surveys were included in the analysis:

Health Survey for England (HSE 2007)

Scottish Health Survey (SHeS 2008)

Welsh Health Survey (WHS 2007)

Adult Psychiatric Morbidity Survey (APMS 2007)

English Longitudinal Survey of Aging (ELSA Wave 4 2007)

Family and Children’s Survey (FACS 2007)

Family Resources Survey (FRS 2008) and the FRS Disability

Follow-up (1997)

Living in Wales (2008)

Low Income Diet and Nutrition Survey (LIDNS 2005)

National Diet and Nutrition Survey (NDNS 2008)

Life Opportunities Survey (LOS 2010)

Understanding Society (US 2010/11)

Four of the surveys reviewed technically should have been excluded because they focus on a subgroup of the population (ELSA, FACS, LIDNS and the FRS Disability follow-up). They have been included because they contain different forms of questions that could be of interest and that were not included on the surveys within the inclusion criteria.


1.17 Analysis

1.17.1 Statistical approachThe statistical software package SPSS was used to manage the data,

derive variables, and generate prevalence estimates using different

indicators of visual impairment (from all the eligible national surveys for

which we were able to obtain relevant data). The rates generated are at

the national level (representing England, Scotland, Wales or Britain) and

shown broken down by age and sex to facilitate comparison across

surveys covering different age ranges. Although ethnicity was also a

variable of interest, generally the sample size for this group was too small

for reliable analysis.

Publicly archived datasets tend not to contain age as a continuous

variable, but rather aggregate it into age groups (for example, 16 to 24, 25

to 34). This is a common practice done to avoid disclosure of respondent

identity resulting from multiple variables archived in combination. However,

the age bands provided varied between surveys, and so there is some

variation in the bands used here to report prevalence.

Where children (aged 15 or under) were included in the archived survey

sample, they have been excluded from these analyses. There was some

variation between surveys as to whether data were collected from

respondents aged 16 and 17. Where data were available on 16 and 17

year olds, these have been included.

1.17.2 WeightingThe data used in the analyses have been weighted using the relevant

survey specific weighting variables, where these were made available on

the archived dataset. Bases are always presented unweighted. This

corrects for selection probabilities (for example, on some surveys people in


single person households will be more likely to be selected for an interview

than people in households with more than one adult occupant) and known

patterns on non-response (for example, by comparing the profile of an

achieved sample with the profile of the known population, it usually

emerges that young men were the least likely to take part. They can then

be weighted up in the survey analysis). Robertson and Emerson, in

Estimating the number of people with co-occurring vision and hearing

impairments in the UK, argue that people with sensory impairments may

also be less likely to take part in surveys. However, with the data currently

available, it is not possible to develop weights for general population

surveys to compensate for this bias in survey participation.xxxv

1.17.3 Missing dataRespondents who refused to answer a question, or who skipped a

question they should have answered on a paper questionnaire, have been

excluded from the analysis. Likewise, ‘don’t know’ responses have also

been excluded. For this reason there may be small differences the bases

reported for individual questions within the same survey.


3 SurveysThis chapter provides a summary of each survey included in the review,

covering:

1. Survey background, including the profile of the sample.

2. Relevant questions, and how these were administered.

3. Code-frames used to classify respondent answers on type of

impairment post data-collection, where these were available.

4. The prevalence of visual impairment obtained using the data

collected.

5. A discussion of any survey specific methodological issues arising,

and how these might impact on interpretation of the rates produced.

6. Survey contacts and where further information can be obtained.

Comparisons between the surveys are made in Chapter 5, and

overarching conclusions and recommendations are drawn out in Chapters

6 and 7.


1.18 Health Survey for England (HSE)The Health Survey for England (HSE) is a cross-sectional survey

undertaken annually since 1994. The NHS Information Centre

commissions HSE with funding from the Department for Health. It is

representative of people (aged 16 and over) living in private households in

England. Both an initial lay-interview and a nurse follow-up visit are

conducted with everyone in selected households (up to ten adults and two

children). Core topics are run every year, with different additional topics

included each year. Only HSE 2000 has had a module of questions asking

specifically about visual impairment. In that survey year, HSE focused on

older people and also included a sample selected from communal

residential settings.

1.18.1 Visual impairment questions asked In HSE 2007 two questions were asked that provide indicators of self-

reported visual impairment. These questions were administered as part of

the face-to-face Computer Assisted Personal Interview (CAPI) in a module

of questions on ‘general health’.

Respondents were first asked whether or not they have any long-standing

illness or disability, with ‘yes/no’ response options. A ‘yes’ response was

followed with an open-ended question, in which details of up to six ‘health

conditions’ are collected. Respondent details are keyed into the laptop by

the interviewer verbatim.

The exact wording of the questions used is given in Figure 4.1. Other than

in HSE 2000, there have been no questions in the HSE questionnaire that

specifically prompted for responses relating to visual impairment.


Figure 4:1 HSE 2007 questions on long-standing illness, disability or infirmity

LongIllDo you have any long-standing illness, disability or infirmity? By long-standing I mean anything that has troubled you over a period of time, or that is likely to affect you over a period of time?1 Yes2 No

IllsTxt {Ask if LongIll = Yes}What (else) is the matter with you?OPEN RESPONSE: INTERVIEWER: RECORD VERBATIM RESPONSE FULLY. PROBE FOR DETAIL. Up to six health conditions can be recorded.

1.18.2 Long-standing illness code frameAfter data collection, the responses given at the question IllsTxt were

assigned to codes by trained coders back in the office. Each response is

assigned to one of the long-standing illness codes shown in Figure 4.2.

These codes are based on the higher levels of the International Disease

Classification (ICD) system version 10.xxxvi

Figure 4:2 Long-standing illness code frameNeoplasms1. Cancer including lumps, masses, tumours and growths and benign

(nonmalignant) lumps and cystsEndocrine/nutritional/metabolic diseases2. Diabetes3. Other endocrine/metabolicMental, behavioural and personality disorders4. Mental illness/anxiety/depression5. Mental handicapNervous system (central and peripheral including brain)6. Epilepsy/fits/convulsions


7. Migraine/Headaches8. Other problems of the nervous systemEye complaints9. Cataract/poor eye sight/blindness10. Other eye complaintsEar complaints11. Poor hearing/deafness12. Tinnitus/noises in the ear13. Meniere's disease/ear complaints causing balance problems14. Other ear complaintsComplaints of heart, blood vessels and circulatory system15. Stroke/cerebral haemorrhage/cerebral thrombosis16. Heart attack/angina17. Hypertension/high blood pressure18. Other heat problems19. Piles/ haemorrhoids20. Varicose veins/phlebitis in lower extremities21. Other blood vessels/embolicComplaints of respiratory system22. Bronchitis/emphysema23. Asthma24. Hay fever25. Other respiratory complaintsComplaints of the digestive system26. Stomach ulcer/ abdominal/ hernia/rupture27. Other digestive complaints (stomach, liver, pancreas, bile ducts,

small intestine -duodenum, jejunum and ileum)28. Complaints of bowel/colon 29. Complaints of teeth/mouth/tongueComplaints of genito-urinary system30. Kidney complaints31. Urinary Tract infections32. Other bladder problems/ incontinence33. Reproductive system disordersMusculoskeletal - complaints of bones/joints/muscles34. Arthritis/rheumatism/fibrositis35. Back problems/slipped disc/spine/neck36. Other problems of bones/joints/muscles


Other long-term health conditions37. Infectious and parasitic disease38. Disorders of blood and blood forming organs and immunity disorders39. Skin complaints40. Other complaintsAdditional codes41. Unclassifiable42. Complaint no longer present43. Not answered/ Refusal

A manual and training is provided to survey data coders with details of

what should be included under each code. Descriptions of what to include

under each of the two high level ‘eye complaint’ codes are listed in Figure

4.3.

Figure 4:3 Descriptions of codes related to visual impairmentCODE 9'Cataract/poor eye sight/blindness

CODE 10Other eye complaints

- Operation for cataracts, now need glasses

- Bad eyesight, restricted vision, partially sighted

- Bad eyesight/nearly blind because of cataracts

- Blind in one eye, loss of one eye

- Blindness caused by diabetes- Blurred vision- Detached/scarred retina- Hardening of lens- Lens implants in both eyes- Short sighted, long sighted,

myopia- ‘Trouble with eyes’- ‘Eyes not good’- Tunnel vision

- Astigmatism- Buphthalmos- Colour blind- Double vision- Dry eye syndrome, trouble

with tear ducts, watery eyes- Eye infection, conjunctivitis- Eyes are light sensitive- Floater in eye- Glaucoma- Haemorrhage behind eye- Injury to eye- Iritis- Keratoconus- Night blindness- Retinitis pigmentosa- Scarred cornea, corneal

ulcers


- Squint, lazy eye- Sty on eye

1.18.3 Visual impairment prevalence estimates Overall, using the process employed in HSE 2007, 2.2% of respondents

were coded as having some form of visual impairment. Presence of visual

impairment was classified as either code 9 (cataract/poor eye

sight/blindness) or code 10 (other eye complaint) being assigned to a

response given at Illstxt post data collection. Breakdowns of this figure by

age group and sex are shown in Tables 4.1 and 4.2.

Table 4:1 Prevalence of visual impairment, by age group (HSE 2007)Age 18-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90+ Total

% 0.7 0.8 0.7 1.6 1.2 2.3 4.8 11.4 4.3 2.2Base 134 884 1153 1250 1094 1077 727 333 46* 6698*note small base size, this makes estimates unreliable.

Table 4:2 Prevalence of visual impairment, by sex (HSE 2007)Sex Male Female Total% 2.5 2.0 2.2Base 2974 3724 6698

1.18.4 Methodological issuesThere are number of measurement issues in relation to the collection of

data on visual impairment in HSE.

Firstly, respondents may not consider a visual impairment to be an ‘illness,

disability or infirmity’. This has been identified as a particular issue among

older respondents who may attribute eyesight problems to ‘aging’.xxxvii Such

people would answer ‘no’ at the screening question, and so not even be

asked the questions about ‘what is the matter with’ them. This would result

in the under-reporting of visual impairments. Similarly respondents may not


report conditions that have been ‘undiagnosed’ or where they are unaware

that a problem exists. Visual impairment may be especially vulnerable to

this type of reporting error.

Secondly, there is an issue in relation to the reporting of co-morbidities or

conditions regarded as symptomatic of another prior or primary condition.

For example, a respondent who has diabetes may state ‘diabetes’ at

Illstxt, but not specify related conditions such retinopathy (or loss of kidney

function). This would mean that the condition is coded once (as an

endocrine condition) but additional codes (eyesight problems, genitourinary

problems) are not recorded. Currently interviewers are instructed to ‘probe

for details’ in relation to each condition given. However, it is likely that

respondents could still overlook secondary impairments, especially if they

are not considered the ‘main’ element of their condition. Generally, but not

consistently, conditions are recorded rather than symptoms.

Thirdly, respondents’ original open responses to Illstxt are not provided in

the UK Data Archive (although they can be obtained by request)1.

Furthermore, the dataset combines codes nine and ten into a single item

on visual impairment. Therefore, conditions such as a blindness and

cataracts are grouped with ‘squints’ or having a ‘lazy eye’. This could lead

the definition of a ‘visual impairment’ being too broad to be useful.

In addition prevalence rates obtained in HSE could be influenced by:

Impact of sight loss on survey participation

Context (location in a health module and health survey). This could

potentially influence respondents’ expectations of what they should

report. For example respondents may report impairments with a

formal diagnosis, but not conditions that have not been diagnosed.

1 One reason for this is to protect anonymity; for example it could be theoretically possible to identify a respondent by combining details of a rare condition with other variables held on them (e.g. geographical region, age etc).


Likewise, respondents many not report visual impairments that are

corrected by low vision aids.

1.18.5 Study contacts and further informationRachel Craig, Health Survey for England (HSE) director, NatCen.

http://www.ic.nhs.uk/statistics-and-data-collections/health-and-lifestyles-

related-surveys/health-survey-for-england


http://www.ic.nhs.uk/statistics-and-data-collections/health-and-lifestyles-related-surveys/health-survey-for-england

http://www.ic.nhs.uk/statistics-and-data-collections/health-and-lifestyles-related-surveys/health-survey-for-england

1.19Scottish Health Survey (SHeS)The Scottish Health Survey (SHeS) is a continuous, cross-sectional survey

commissioned by the Scottish Government. The methods used in the

SHeS were originally modelled on the methods used for HSE, in order to

provide comparable data for Scotland. Households were selected from

across Scotland using random probability sampling. All resident adults

(age 16 or over) were invited to take part in an interview. A sub-sample of

respondents was also invited to take part in a nurse visit.

1.19.1 Visual impairment questions asked Questions in SHeS are administered in a face-to-face CAPI interview. A

similar approach to questioning is adopted as used in HSE: respondents

are first asked whether or not they have a long-term health condition or

disability. Only those who say ‘yes’ are then asked an open-ended follow

up question in which they are asked to give details of their health condition

or disability. Both these questions are asked as part of a module of

questions on general health.

Figure 4:4 SHeS 2008 ‘long-standing physical or mental condition or disability’ questions

LongIl08Do you have a long-standing physical or mental condition or disability that has troubled you for at least 12 months, or that is likely to affect you for at least 12 months?1. Yes2. No

{Ask if LongIl08=Yes} IllsMWhat [else] is the matter with you?OPEN RESPONSE: INTERVIEWER: RECORD FULLY. PROBE FOR DETAIL.


Questions repeated to capture up to six conditions.

All information collected at IllsM is coded post data-collection using the

same code-frame used in HSE (see Section 4.1).

1.19.2 Visual impairment prevalence estimates

In total, in SHeS 2008, 2.3% of respondents reported having some form of

visual impairment, in line with the figure collected by HSE (see 4.1). As

with HSE, visual impairment is classified with either code 9 (Cataract/poor

eye sight/blindness) or code 10 (Other eye complaint) being assigned to

the response given at IllsM post data collection. Breakdowns of prevalence

of visual impairment by age group and sex are shown in Tables 4.3 and

4.4.

Table 4:3 Prevalence of visual impairment, by age group (SHeS 2008)Age 18-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90+ Total% 0.0 0.1 0.3 1.2 1.6 2.8 4.2 9.9 20.5Base 105 679 909 1211 1153 1095 783 332 44* 6311

*note small base size.

Table 4:4 Prevalence of visual impairment, by sex (SHeS 2008)Sex Male Female Total% 2.3 2.2 2.3Base 2770 3541 6311

1.19.3 Methodological issuesThe potential measurement issues in relation to the SHeS data on visual

impairment are similar to those discussed in relation to HSE. To

summarise:

1. Respondents may have some form of visual impairment but not

consider it to be a ‘long-standing physical or mental condition’ or a

‘disability.’


2. Respondents may not report visual impairments that are co-morbid

with or symptoms of other conditions.

3. Data on specific conditions are not available; inclusion parameters of

what constitutes a visual impairment may be too broad.

Likewise, results may be influenced by the health survey context and the potential impact of sight loss on survey participation.

1.19.4 Study contacts and further informationCatherine Bromley, Scottish Health Survey director, ScotCen

www.scotland.gov.uk/Topics/Statistics/Browse/Health/scottish-health-survey


http://www.scotland.gov.uk/Topics/Statistics/Browse/Health/scottish-health-survey

http://www.scotland.gov.uk/Topics/Statistics/Browse/Health/scottish-health-survey

1.20Welsh Health Survey (WHS) 2007 The Welsh Health Survey (WHS) is an annual cross-sectional survey

commissioned by the Welsh Government (WG). The population surveyed

is representative sample of the adult population (16+) living in private

households in. All adults living in randomly selected households are invited

to take part in the survey. In addition up to two children per household are

randomly selected to take part (these have been excluded from the current

analysis).

For the WHS a short interviewer administered questionnaire is given to

establish who lives in the household. After this all adults in the household

are given a paper questionnaire to complete in their own time, this

questionnaire is either picked up the interviewer on a return visit or

returned by post. All paper questionnaires were available in both English

and Welsh.

1.20.1 Visual impairment questions asked

The 2007 WHS paper self-completion questionnaire contained one

question specifically on eyesight (SEE). This question (and how it was

visually presented on paper) is shown in Figure 4.5.

Figure 4:5 WHS 2007 question on eyesight quality

In addition the WHS paper questionnaire contained two items (LLTI and

LLTICDE) designed to capture long-term illness, health problems or

disabilities. These questions adopt broadly the same approach used in


HSE and SHeS. These questions (and how they are visually presented)

are shown in Figure 4.6.

Figure 4:6 WHS 2007 questions on health conditions and disabilities

All information collected at LLTICDE was coded post data-collection using

a code-frame based on the International Disease Classification (ICD)

system. The code frame used is the same as used in HSE (see Section

4.1).

It should be noted that although respondents were prompted to provide

details of ‘one illness only’, up to four ICD-10 codes could be entered

depending on the detail of the response given.


In total 2.6% of respondents surveyed said their eyesight was not good

enough to see the face of a person across the room. In addition a further

3.0% of respondents stated they could see the face of someone across a

room but ‘with difficulty.’ A breakdown of responses to ‘See’ by age and

sex is provided in Tables 4.5 and 4.6.


Table 4:5 Prevalence of self-reported difficulties in seeing the face of someone across a room, by age group (WHS)

Age 16-19 20-29 30-39 40-49 50-59 60-69 70+ Total% % % % % % % %

SEE= Yes, but with difficulty 1.8 2.0 1.6 2.2 3.3 2.9 5.8 3.0SEE= No, not at all 2.4 2.8 1.9 2.3 2.3 1.6 4.4 2.6Base 796 1574 1929 2320 2376 2284 2524 13803

Table 4:6 Prevalence of self-reported difficulties in seeing the face of someone across a room, by sex (WHS)

Sex Male Female Total% % %

SEE= Yes, but only with difficulty 2.2 3.7 3.0SEE= No, not at all 2.3 2.8 2.6Base 6361 7442 13803

The number of respondents who reported a visual impairment at LLTICDE (the question on types of long-term health condition that limit daily

activities) was much lower. A breakdown of response to LLTICDE by age

and sex is provided in Tables 4.7 and 4.8.

Table 4:7 Prevalence of self-reported visual impairment at Llticde, by age group (WHS)

Age 16-19 20-29 30-39 40-49 50-59 60-69 70+ Total% % % % % % % %

Llticde = Cataract /poor eyesight/ blindness 0.3 0.3 0.1 0.1 0.6 0.5 1.4 0.5LltIcde =Other eye problem 0.0 0.0 0.1 0.0 0.2 0.1 0.6 0.2Any eye condition 0.3 0.3 0.2 0.2 0.7 0.6 2.0 0.7Base 800 1581 1931 2305 2343 2238 2421 13619


Table 4:8 Prevalence of self-reported visual impairment at Llticde, by sex (WHS)


Llticde = Cataract/poor eyesight/blindness 0.4 0.6 0.5LltIcde =Other eye problem 0.2 0.2 0.2Any eye condition 0.6 0.8 0.7Base 6266 7353 13619

A comparison of response patterns between the two different questions is

shown in Figure 4.7.

Figure 4:7 Comparisons between ‘See’ and ‘LLticde’ by sex (WHS)

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

Male Female

Can't see/ difficultiesseeing someone acrossa room reported at SEEVisual impairmentreported at Llticd

1.20.3 Methodological issuesWhile 5.6% of WHS respondents report that they find it difficult to see

someone across a room (or are unable to see someone across a room)

only 0.7% respondents report that they have a visual impairment at Llticd.

This indicates that the current WHS questions on health conditions (Llti

and Llticde) are not capturing all respondents who have some form of

visual impairment, and/or that reported difficulty in seeing someone across

a room is too inclusive a characteristic. The discrepancy between the

results could be because:


Respondents do not feel the problems with their sight ‘limit’ their

daily activities.

Respondent are only instructed to provide details of one illness at

LLticd. This could lead to respondent prioritising the reporting of

other conditions.

Respondents may have some form of visual impairment but not

consider it to be a ‘long-term illness’ ‘health condition’ or a ‘disability.’

As with HSE and SHeS, the actual conditions reported at LLticde are not

archived for general public access. However, unlike HSE and SHeS, WHS

does provide a breakdown between codes 9 and 10. The majority of

reports of visual impairment fall into code 9 rather than code 10, which

could be taken as evidence respondents are more likely to report ‘serious’

conditions. However, without a full breakdown of what actual conditions

respondents reported it is not possible to know precisely what conditions

are being captured.

In addition, other issues are raised by the questionnaire mode (self-

completion as opposed to interviewer-administered). It is possible that

sight loss influences survey participation more in self-completion modes

than in other forms of administration2. Likewise, it is possible that the self-

administered mode could increase the likelihood of proxy respondents

being used (i.e. where another household member completes the paper

questionnaire on behalf of the person who is visually impaired). These will

not always be recorded as proxy responses.

Although the question ‘SEE’ may also be open to respondent

interpretation. For example, the question asks respondents whether they

can ‘see the face of someone across a room’ but does not specify whether

a face as to be seen clearly (enough to recognise the face) or the size of 2 In WHS interviewers who conduct the initial household questionnaire can offer to read out questions to blind respondents if required. However, no record is available on the archive of how often this occurs in practice.


the room. Therefore, there is scope for respondents with visual

impairments to answer ‘yes’ if they do not consider their sight problems as

serious. Likewise, respondents with certain types of impairment (e.g.

tunnel vision) may not report any sight impairments at this question.

*Issues of use of low vision aids – question only asked about

glasses/contacts where these are usually worn (i.e. excludes those who

need glasses but fail to use them).

1.20.4 Study contacts and further informationKatharine Sadler and Melanie Doyle, Welsh Health Survey directors,

Health and Wellbeing Team, NatCen.

http://wales.gov.uk/topics/statistics/theme/health/health-survey/?lang=en


http://wales.gov.uk/topics/statistics/theme/health/health-survey/?lang=en

1.21Adult Psychiatric Morbidity Survey (APMS) 2007The Adult Psychiatric Morbidity Survey 2007 (APMS 2007) is a survey on

the prevalence of poor mental health of people living in England,

commissioned by the NHS Information Centre for health and social care.

The survey collected information from a representative sample of adults

living in private households. Interviews were conducted face-to-face,

although sensitive questions were asked using a computerised self-

completion form.

1.21.1 Visual impairment questions asked The APMS contained two questions relevant to this study. The question

was asked in the ‘General Health’ section of the face-to-face interview. The

question is shown in the following box.

Figure 4:8 APMS 2007 Questions on general healthVisual impairments are captured using code 7 at question ‘Health’HealthNow please look at the health conditions listed on this card. Have you ever had any of them since the age of 16?SHOWCARD GCODE ALL THAT APPLY1 Cancer2 Diabetes3 Epilepsy/fits4 Migraine or frequent headaches5 Dementia or Alzheimer's disease6 Anxiety, depression or other mental health issue7 Cataracts/eyesight problems (even if corrected with glasses or contacts)8 Ear/hearing problems (even if corrected with a hearing aid)9 Stroke10 Heart attack/angina11 High blood pressure12 Bronchitis/emphysema


13 Asthma14 Allergies15 Stomach ulcer or other digestive problems16 Liver problems17 Bowel/colon problems18 Bladder problems/incontinence19 Arthritis20 Bone, back, joint or muscle problems21 Infectious disease22 Skin problems23 Other, please specify96 None of these

IF Health = RESPONSE THENHYearHave you had (name of health condition) in the last 12 months?Please say 'yes' if you have had this condition, even if you have not experienced any symptoms because you use medication or an aid.INTERVIEWER: AN AID IS SOMETHING WHICH ASSISTS SOMEONE TO OVERCOME AN IMPAIRMENT, SUCH AS A WALKING STICK ZIMMER FRAME, GLASSES OR HEARING AID.1 Yes2 No

It should be noted that although ‘Health’ was administered using a

showcard, interviewers were able to read out the list if respondents

exhibited difficulties with vision or literacy.

1.21.2 Visual impairment prevalence estimates In total 17.6% of respondents reported having ‘cataracts or eyesight

problems’ in the last 12 months. Respondents were instructed to include

eyesight problems that were corrected with glasses or contact lenses.

A breakdown of responses by age and sex are shown in Tables 4.9 and

4.10.


Table 4:9 Prevalence of self-reported cataracts/eyesight problems in past 12 months, by age group (APMS)

Age 18-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90+ TotalCataracts/ eyesight problems

% 9.0 11.2 9.5 14.5 18.7 18.4 27.0 34.1 45.8 17.6Base 111 810 1262 1291 1160 1189 940 461 48* 7272*note small base size.

Table 4:10 Prevalence of self-reported cataracts/eyesight problems in past 12 months, by sex (APMS)

Sex Male Female TotalCataracts/ eyesight problems

% 16.4 18.4 17.6Base 111 810 7272

1.21.3 Methodological issuesThe total number of respondents reporting visual impairments is higher for

APMS than for the other surveys reviewed (17.6% respondents reporting

having ‘Cataracts/eyesight problems’). This is likely to be mainly due to:

1. Respondents were prompted to include problems corrected by

glasses or contacts, which may not have been mentioned otherwise.

2. Respondents are provided with a list of different types of ‘health

conditions’ at ‘Health’ rather than being asked an open question on

whether they have any health conditions. This approach could

prompt people to include problems with vision they might otherwise

not have included.

The APMS measure is limited in that it provides no indication of the type of

visual impairment respondents may have. Likewise, as with other surveys

described, there is no indication of the severity of the visual impairment.


The definition of visual impairment used in this survey (particularly the

inclusion of eyesight problems that are fully correctable using glasses or

contact lenses) may be too broad to be of use for many researchers or

policy experts with an interest in visual impairment issues.

In addition, as with other surveys, results may be influenced by the impact

of visual impairment on survey participation.

1.21.4 Study contact and further informationSally McManus, Health and Wellbeing team, NatCen.

http://www.mentalhealthsurveys.co.uk/


http://www.mentalhealthsurveys.co.uk/

1.22English Longitudinal Study of Aging (ELSA) Wave 4Data from the English Longitudinal Study of Ageing (ELSA) have been

used quite extensively to look at the prevalence and circumstances of older

people with visual impairment. It has demonstrated how poor eyesight can

influence health, quality of life, mobility and the ability to look after oneself

and take part in social activities, as well as economic wellbeing.xxxviii

Interestingly, data from the survey has also suggested that older people

with poor eyesight may tend to have good social networks and access to

informal care. The ELSA findings demonstrate the need for better

diagnosis and treatment of sight problems and better strategies to screen

older people for visual impairment.

ELSA is a longitudinal study of people aged 50 and over and their younger

partners, living in private households in England. Respondents are

interviewed every 2 years to measure change in their health, economic and

social circumstances. The survey programme is the result of collaboration

between University College London, the Institute for Fiscal Studies (IFS),

and the National Centre for Social Research (NatCen). Funding for the first

four waves of ELSA has been provided by the US National Institute on

Aging, and a consortium of British Government departments.

Technically, the survey is not eligible for inclusion because it samples a

subgroup of the population (respondents aged 50 or more, and their

partners). However, it has been included as it uses a different style of

questions to those discussed previously. Cohort studies are also of

particular value because their longitudinal structure allows for investigation

of causality and change over time.

The ELSA data analysed for this review was collected during wave four of

the study, conducted between 2008 and 2009. The survey comprised a


face-to-face interview, a self-completion questionnaire, and a nurse visit.

The questions of interest were included in the face-to-face interview.

1.22.1 Visual impairment questions asked ELSA also includes questions on whether respondents have ever been

diagnosed with specific ocular conditions: glaucoma, diabetic eye disease,

macular degeneration and cataracts.

The questions are shown in the box on the next page. Please note that

ELSA Wave four uses dependent interviewing in many of its modules. This

means that certain questions were checking the information respondents

had given at earlier waves rather than asking questions for the first time.

The questions from the ELSA wave one are also shown in Figure 4.9 with

examples of the checks used at Wave 4.


Figure 4:9 ELSA questions on ocular conditionsOCCULAR CONDITIONSHeop (Wave 1)Has a doctor or optician ever told you that you have (or have had)...READ OUT EACH IN TURN AND CODE ALL THAT APPLY...INCLUDE DIABETIC RETINOPATHY IN CODE 2INCLUDE AGE RELATED MACULOPATHY IN CODE 31 Glaucoma or suspected glaucoma?2 diabetic eye disease?3 macular degeneration?4 cataracts?96 None of these

HEOPC (Wave 4)Our records show that when we last interviewed you, you said that hadhad (or had been told by a doctor had had) {CONDITION} .INTERVIEWER: Code 1 below unless respondent spontaneously disputes this record.1 Yes2 No

HEOPS (Wave 4)IF confirms previous eye condition = Yes [HeOpC =1]Do you still have {CONDITION} ?1 Yes2 No

HEOPT (Wave 4)Has a doctor or optician told you that you have (or had)...INTERVIEWER: Read out each (except those previously coded) and code all that apply.INCLUDE DIABETIC RETINOPATHY IN CODE 2INCLUDE AGE RELATED MACULOPATHY IN CODE 31 Glaucoma or suspected glaucoma?2 diabetic eye disease?3 macular degeneration?4 cataracts?


96 None of these

In addition ELSA includes a question in which respondents are asked to

rate their own eyesight (see Figure 4.10).

Figure 4:10 ELSA question on self-rated eyesightHEEYEIs your eyesight (using glasses or corrective lenses if use them)...INTERVIEWER: Read out...1 ...excellent,2 very good,3 good,4 fair,5 or, poor?6 SPONTANEOUS CODE: Registered or legally blind

1.22.2 Visual impairment prevalence estimates In total, 20.5% of ELSA respondents reported having an ocular condition at

wave 4. The proportion of ELSA respondents reporting specific ocular

conditions, are summarised in Tables 4.11 and 4.12.

Table 4:11 Prevalence of self-reported ocular conditions, by age group (ELSA)

Age 50 to 59 60 to 69 70 to 79 80 to 89 90 plus TotalOcular conditions % % % % % %Glaucoma/ suspected glaucoma 2.0 3.9 6.6 8.8 13.2 4.6Diabetic Eye Disease 1.0 1.4 2.5 1.5 1.5 1.6Macular Degeneration 0.9 1.6 4.6 10.0 11.8 3.1Cataracts 3.2 10.6 25.9 31.2 36.0 14.5Any of the above 6.6 15.7 34.3 41.6 52.2 20.5Base 2899 3506 2358 982 136 9881


Table 4:12 Prevalence of self-reported ocular conditions, by sex (ELSA)

Sex Male Female TotalOcular conditions % % %Glaucoma/ suspected glaucoma 4.7 4.5 4.6Diabetic Eye Disease 1.7 1.4 1.6Macular Degeneration 2.5 3.6 3.1Cataracts 11.9 16.6 14.5Any of the above 17.6 22.8 20.5Base 4421 5460 9881

In addition to being asked about specific ocular conditions, respondents

were also asked to rate the overall quality of their eyesight (when using

corrective lenses if appropriate). These are summarised in Tables 4.13 and

4.14.

Table 4:13 Prevalence of self-rated quality of eyesight, by age group (ELSA)

Age 50 to 59 60 to 69 70 to 79 80 to 89 90 plus TotalSelf-rated eyesight % % % % % %Excellent 19.2 16.1 11.4 8.9 7.4 15.0Very good 34.5 35.7 32.0 26.3 18.4 33.3Good 36.7 37.8 40.2 39.7 26.5 38.1Fair 8.1 8.5 11.8 15.5 23.5 10.1Poor 1.4 1.7 4.0 8.1 19.9 3.1SPONTANEOUSRegistered blind 0.1 0.3 0.6 1.5 4.4 0.5Base 2900 3509 2359 986 136 9,890

Table 4:14 Prevalence of self-rated quality of eyesight, by sex (ELSA)Sex Male Female Total

Self-rated eyesight % % %Excellent 16.7 13.7 15.0Very good 34.0 32.7 33.3Good 36.9 39.1 38.1


Fair 9.6 10.4 10.1Poor 2.4 3.6 3.1SPONTANEOUSRegistered blind or partially sighted 0.5 0.5 0.5Base 4426 5464 9890

In total 0.5% of ELSA respondents reported being registered as blind or

partially sighted when asked to rate their own eyesight. This was not a

direct question, and therefore is likely to represent an underestimate of the

true rate.

The proportion of respondents describing their eyesight as ‘fair’ (10.1%) or

‘poor’ (3.1%) was lower than the proportion stating that they had an ‘ocular

condition’ (20.5%). This led to us to examine the differences in perceptions

of eyesight quality between respondents who did and did not report having

ocular conditions. The relationship between self-rated eyesight quality and

ocular condition is illustrated in Figure 4.11.

Figure 4:11 Self-rated quality of eyesight, by whether have a self-reported ocular condition (ELSA)

Figure 4.11 shows that the majority of people who reported having an

ocular condition still rated their eyesight highly. 39.3% of people with an


ocular condition rated their eyesight as ‘good’, 21.9% rated their eyesight

as ‘very good’, and 7.8% even rated their eyesight as ‘excellent’.

In addition, there is little variation between the proportion of respondents

who rate their eyesight as being ‘good’ between the two groups (39.3% of

people with ocular conditions rated their eyesight as ‘good’; 37.8% of

people without ocular conditions rated their eyesight as ‘good.’). This

indicates that the self-rating of eyesight is distinct from the reporting of the

presence of ocular conditions. This is discussed further in Chapter 6.

1.22.3 Methodological issues

ELSA asks different types of questions to those included in the general

population survey previously discussed i.e. it asks respondents whether

they have specific ocular conditions (glaucoma, Diabetic eye disease or

cataracts). In ELSA 20.5% of respondents reported having a specific

ocular condition. As the target population is different to the surveys

previously discussed (only respondents aged 50 and over and their

partners are interviewed) a higher prevalence rate of visual impairments is

to be expected. However, when making comparisons between

respondents aged 50+ in HSE and SHeS reports of eyesight conditions are

still higher in ELSA (see Chapter 5 for a direct comparison).

Currently ELSA only asks about four types of ocular condition. Therefore,

other types of visual impairment may be excluded. Nonetheless, this type

of question leads to a higher level of reporting than found using general

health condition approach used in the general population surveys

reviewed.

1.22.4 Study contacts and further informationKate Taylor, English Longitudinal Survey of Aging (ELSA) director, NatCen

James Nazroo, Manchester University.

http://www.ifs.org.uk/elsa/


http://www.ifs.org.uk/elsa/


1.23 Family and Children Survey (FACs) 2006-2007

The Families and Children Study (FACS), formerly known as the Survey of

Low Income Families (SOLIF), originally provided a new baseline survey of

Britain's lone-parent families and low-income couples with dependent

children. The survey was named SOLIF for Waves 1 and 2, and FACS

from Wave 3 onwards.

The FACS study has become a 'true panel', whereby respondents in 1999

have been re-interviewed in subsequent annual waves. Starting with Wave

3 (2001) the survey was extended to include higher-income families,

thereby yielding a complete sample of all British families (and the

subsequent name change). From Wave 4 (2002) onwards, longitudinal

comparisons can be made.

Technically, the survey is not eligible for inclusion because it samples a

subgroup of the population (families with children), rather than the general

population. However, it has been included as it uses a different style of

questions to those discussed previously.

All the questions reviewed here were administered in a face-to-face CAPI

interview.


FACs contains two questions on visual impairment, are included in a

general health question module. The questions mirror the approach used

in HSE and SHeS: respondents are first asked whether they have any form

of longstanding illness, disability or infirmity and then, if they respond in the

affirmative, are asked a follow-up question about the types of conditions

that they have. However, unlike HSE and SHeS, at the follow up question

respondents are provided with a closed list of categories on illness or

disability rather than being asked an open question.

The wordings of these questions are shown in Figure 4:12 below.


Figure 4:12 FACS question on long-standing illness or disabilityHea2Do you have any longstanding illness, disability, or infirmity of any kind? By longstanding I mean anything that has troubled you over a period of time or that is likely to affect you over a period of time?1 Yes2 No

Hea3SHOWCARD What kind of illness or disability do you have?1 Problem with arms, legs, hands, feet, back or neck (including arthritis or rheumatism)2 Difficulty in seeing3 Difficulty in hearing4 Skin conditions, allergies5 Chest, breathing problem, asthma, bronchitis6 Heart, blood pressure or blood circulation problems7 Stomach, liver, kidney or digestive problems8 Diabetes9 Depression, bad nerves10 Mental illness or suffer from phobia, panics or other nervous disorders11 Learning difficulties (or mental handicap)12 Epilepsy13 Other health problems or disabilities

1.23.2 Visual impairment prevalence estimates In total, 0.6% of respondents who took part in FACS reported having difficulty in seeing at Hea3. A breakdown of prevalence by age and sex is shown in Tables 4.15 and 4.16.

Table 4:15 Prevalence of self-rated difficulty in seeing, by age group (FACS)

AgeUnder

18 18-19 20-29 30-39 40-49 50-59 60-69 70-79 TOTAL% % % % % % % %


Difficulty seeing at Hea3 0.0 0.0 0.2 0.5 0.6 1.5 7.9 0.0Base 10* 64* 1285 2957 2659 602 38* 4* 7619*Note the small base size for these estimates, which makes them unreliable.

Table 4:16 Prevalence of self-rated difficulty in seeing, by sex (FACS)Sex Male Female Total

% % %Difficulty seeing at Hea3 2.2 0.6 0.6Base 137 7482 7619

There was a difference between men and women in the reporting of

‘difficulty seeing’ (2.2% of men, 0.6% of women). This is likely to be due to

sampling issues: adult respondents on FACS were the available parent

with primary responsibility for childcare. This was usually the mother.

When fathers were available to be the survey respondent, it is probable

that poor health or the presence of an impairment may have made it more

likely that they were home (and not in work). This is likely to account for the

disparity in rates of reporting difficulty in seeing.

1.23.3 Methodological issuesAs with HSE and SHeS, respondents who have visual impairments will

only report them if they consider them to be a ‘long-standing illness,

disability or infirmity.’ It is not clear if respondents will do this, depending on

the nature of their sight loss, how it impacts on them and their opinion of its

severity. This could lead to survey data under-estimating prevalence of

visual impairments.

Unlike HSE and SHeS no information is captured about the type of visual

impairment respondents may have. Likewise, no indication of the severity

of the visual impairment is captured.


The FACs question is different to that used on the other surveys reviewed

in its use of a prompted list of categories after the initial question on

illnesses and disabilities. Understanding Society also adopts this approach,

however the showcard category on visual impairment is phrased in a

different way (in Understanding Society respondents are instructed to

exclude problems corrected by glasses).

It is likely that respondents who report having some form of illness or

disability may be more likely to report a visual impairment if they are

prompted to do so via use of the showcard. To test this hypotheses,

comparisons between FACs responses and HSE and SHeS responses

were examined. As discussed, the population surveyed in FACS is

different to the other surveys reviewed. FACS is a survey of parents in

receipt of Child Benefits, so is younger and more female than the

population in HSE and SHeS. Figure 4.13 therefore focuses on

respondents aged 20-59.

Figure 4:13 Comparing prevalence of visual impairments reported in HSE, SHeS and FACs

0.0%0.2%0.4%0.6%0.8%1.0%1.2%1.4%1.6%1.8%

20-29 30-39 40-49 50-59

Age Group

Prev

alen

ce o

f rep

orte

d vi

sual

im

pairm

ents

HSESHeS

FACs

Figure 4.13 does not support the hypothesis that the prompted list (with an

initial filter question) used in FACs would lead to increased reporting of

visual impairments. Reasons for this could include:


JDardenne, 23/08/11,

ADDUS? Move to discussion section?

Placement of prompted list. Respondents were still only exposed

to the prompted list if they reported a health condition or impairment

first. Therefore, this approach would not increase reporting of visual

impairment among people for whom that is their only impairment.

Phrasing of prompted list. The prompted list cites ‘difficulty

seeing.’ It is possible some respondents with ocular conditions may

not feel they find it difficult to ‘see’.

Interviewer probing. In HSE and SHeS interviewers are trained to

‘probe’ respondents by asking ‘and what else?’ This is designed to

encourage fuller reporting in response to an open question, but may

not have happened in the FACS question, which is administered by

showcard.

Population surveyed. There could be confounding effects due to

the different samples even when age is taken into account. For

example, if people with visual impairments are any less likely to

become parents then they would be less likely to take part in FACs.

As with all the surveys discussed, results may also be influenced by the

impact of visual impairment on general survey participation.

1.23.4 Study contact and further informationClare Tait, Family and Children Survey director, NatCen

http://www.esds.ac.uk/longitudinal/access/facs/l4427.asphttp://www.natcen.ac.uk/facs/


http://www.natcen.ac.uk/facs/

http://www.esds.ac.uk/longitudinal/access/facs/l4427.asp

1.24 Family Resources Survey

The Family Resources Survey (FRS) is a continuous, cross-sectional survey that collects information on the incomes and circumstances of private households in the United Kingdom. DWP sponsors the survey. All adults in the randomly selected households are invited to take part in a face-to-face CAPI interview. A health module is included in the FRS questionnaire to that aims to identify disabled respondents.

1.24.1 Disability questions asked FRS contains two questions that collect information on disabilities and impairments. The wordings of these questions are shown in Figure 4.14. These questions are taken from FRS 2008/2009.

Figure 4:14 FRS questions on long-standing illness or disabilityHealth NOW THERE ARE SOME QUESTIONS ABOUT HEALTH. Do you have any long-standing illness, disability or infirmity? By 'long-standing' I mean anything that has troubled you over a period of at least 12 months or that is likely to affect you over a period of at least 12 months. YesNo

{If Health=Yes}DisDif Does this/Do these health problem(s) or disability(ies) mean that you have substantial difficulties with any of these areas of your life? Please read out the numbers from the card next to the ones which apply to you. 1: Mobility (moving about) 2: Lifting, carrying or moving objects 3: Manual dexterity (using your hands to carry out everyday tasks) 4: Continence (bladder and bowel control) 5: Communication (speech, hearing or eyesight) 6: Memory or ability to concentrate, learn or understand 7: Recognising when you are in physical danger 8: Your physical co-ordination (e.g. balance) 9: Other health problem or disability


10: None of these

As with the other surveys discussed the FRS approach is to first ask

whether respondents have any form of long-standing illness or disability.

Respondents are then asked to describe the type of disability from a

prompted list. However, the list classifies disabilities in terms of the

limitations the place on the respondents’ social functioning rather than type

of medical condition per se. Therefore standard FRS data cannot be used

as a source of data on visual impairment.



Sally- is this the right term? What to keep this section in line with what you said in your introduction.

1.25FRS Disability Follow-up (1997)Although the standard FRS cannot currently be used to measure

prevalence of visual impairments, one off-shoot of the survey was found to

be potential interest to the review. This was the FRS Disability Follow-Up

(1997). The aim of the survey was to find out the size and characteristics of

the disabled adult population of GB. The main topics covered are:

prevalence, severity and types of disability; socio-demographic

characteristics; economic activity; financial circumstances; use of social

and health services; needs for assistance; and social participation.

Respondents who took part in the 1996/97 FRS who matched any one of a

series of sift criteria (based on age, benefit receipt or reported health

problems) were asked to take part in a further face-to-face CAPI interview.

This interview required respondent to detail the cause, type and severity of

their disability, the extra needs and costs which resulted from it, and their

participation in leisure and social activities. Over 7000 people were

interviewed.

Despite the fact this survey did not meet the inclusion characteristics it has

been included in the review. This is because it contains a number of survey

questions on visual capacity that were not identified elsewhere. However,

as the sample frame is different (i.e. the survey only collects information

from those in receipts of benefits related to disability or those aged 75+)

the prevalence estimates discussed are not comparable with the other

general population surveys reviewed.


1.25.1 Visual impairment questions asked in Disability Follow-UpThe FRS Disability study included three measures aiming to capture

disabilities or health conditions. Please note the term ‘disability was not

used’. Instead the question asked about ‘health problems or complaints.’

Figure 4:15 FRS Disability Follow-up questions on health conditionsIntComp1Do you have any long term health problems or complaints which affectyour everyday activities?Yes No

Complntl (IF IntComp1=Yes)What is your health problem or complaint?ASK OR RECORD. TRY TO OBTAIN A MEDICAL NAME. TYPE IN NAME OF FIRST COMPLAINT/DISEASE/PROBLEMUp to 4 complaints coded

IntComp2Do you have any other long term health problem or complaints?ASK OR RECORD AS NECESSARYYesNo

Answers to CompIntl were coded using the ICD codeframe (as discussed

in relation to HSE). However, details of specific conditions are not provided

on the UK Data archive. In addition to this, the FRS disability follow-up

question contained nine questions on visual capacity.

Figure 4:16 FRS Disability Follow-up questions on visual capacitySeeFrnd(Wearing glasses or lenses... )Do you have difficulty recognising a friend across the road?Yes No


Reading(Wearing glasses or lenses… )Do you have difficulty reading ordinary newspaper print?Yes No

Windows (APPLIES IF SeeFrnd=Yes or Reading=Yes)Can I check, (wearing glasses or lenses... ) in a room during daytime,can you tell by the light where the windows are?Yes No

Shape (APPLIES IF Windows=Yes)(Wearing glasses or lenses... )Can you see the shapes of the furniture in this room?Yes No

RecFace (APPLIES IF Shape=l)(Wearing glasses or lenses… )Can you see well enough to recognise a friend if you get close to his orher face?Yes No

ArmLeng (APPLIES IF RecFace~l)(Wearing glasses or lenses... )Can you see well enough to recognise a friend who is an arms lengthaway?Yes No

Headline (Wearing glasses or lenses... )Can you see well enough to read a newspaper headline?Yes No


LargePrt (APPLIES IF Headline=l)(Wearing glasses or lenses... )Can you see well enough to read a large print book?Yes No

Room (APPLIES IF LargePrt=l)(Wearing glasses or lenses... )Can you see well enough to recognise a friend across the room?Yes No


1.25.3 Methodological issues FRS 2008/2009 health questions problematic for those with a

specific interest in visual impairment, as social functioning classification system used does not specifically capture sight problems. Instead, problems with vision are broadly classified under problems with communication (along wit problems hearing and problems speaking).

The FRS disability follow-up questions were more useful. However, as the population general population prevalence can

Question on health conditions do not specifically mention ‘disability’. However, cannot establish whether this could encourage reporting of visual impairments the sample used in not equivalent to the other samples where disability is specifically mentioned.

The questions measuring visual capacity are more detailed than those used in than those found in other surveys, with more scenarios given (e.g. WHS, LOS).

1.25.4 Study contact and further informationJoanne Maher, Family Resources Survey, NatCen

http://www.statistics.gov.uk/ssd/surveys/survey_family_resources.asp


http://www.statistics.gov.uk/ssd/surveys/survey_family_resources.asp

http://www.esds.ac.uk/findingData/snDescription.asp?sn=4090

i Grundy E, Ahlburg D, Ali M, Breeze E, Sloggett A. Disability in Great

Britain: results from the 1996/7 disability survey. 1999: Dept of Social

Security: London.ii Keil S. (2008)

www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_res

earchstats.hcsp RNIB.iii Winyard S, McLaughlan B. (2009) The economic impact of visual

impairment in the UK adult population. RNIB and Access Economics.iv RNIB (2010) Cost oversight? The cost of eye disease and sight loss in the UK today and in the future. RNIB Campaign report 29.v Evans J. International Centre for Eye Health, LSHTM (2006) Prevalence,

causes and impact of sight loss in older people in Britain, Pocklington

Occasional Paper 8.vi Keil S. (2008)

www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_res

earchstats.hcsp, RNIB.vii Association of Directors of Social Services (ADSS) website:

http://www.adass.org.uk/eyes/Progress.txt.viii Winyard S, McLaughlan B. (2009) The economic impact of visual impairment in the UK adult population. RNIB and Access Economics.ix Registered Blind and Partially Sighted People, year ending 31 March

2008: the Information Centre for health and social care. x In the year ending March 2008, there have been 153,000 blind

registrations and 156,300 partially sighted registrations since 2006.



http://www.adass.org.uk/eyes/Progress.txt

http://www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_researchstats.hcsp




1.26 Living in Wales Survey 2008

The Living in Wales Survey was commissioned by the Welsh Government.

It is the main source of information on households and the condition of

homes in Wales. This annual survey was carried out from 2004 to 2008.

The Living in Wales Survey has now been replaced by the National Survey

for Wales, the main stage of which will begin in 2012.

xi See http://www.ons.gov.uk/about-statistics/harmonisation/index.html for

details of the question wording harmonisation programme.xii Tate R, Smeeth L, Evans J, Fletcher A, Owen C, Rudnicka A. (2006) The

prevalence of visual impairment in the UK. A review of the literature. RNIB.xiii Buch H, Vinding T, la Cour M, Appleyard M, Jensen G, Nielsen NV.

Prevalence and causes of visual impairment and blindness among 9980

Scandinavian adults: The Copenhagen City Eye Study. Ophthalmology.

111:1; 53-61.xiv Livingston PM, Carson CA, Stanislavsky YL, Lee SE, Guest CS, Taylor

HR. (1994) Methods for a population-based study of eye disease: the

Melbourne Impairment Project. Ophthalmic Epidemiology. 1(3), 139-148.xv And the more recent Beaver Dam Offspring Study, see: Klein R,

Cruickshanks KJ, Nash SD, Krantz EM, Javier Nieto F, Huang GH,

Pankow JS, Klein BE. (2010) The prevalence of age-related macular

degeneration and associated risk factors. Arch Ophthalmol. 128(6): 750-8.xvi Reidy A, Minassian DC, Vafidis G, Joseph J, Farrow S, Wu J, Desai P,

Connolly A. (1998) Prevalence of serious eye disease and visual

impairment in a north London population: a population based, cross

sectional study BMJ 1316: 1643.xvii Buch H, Vinding T, la Cour M, Appleyard M, Jensen G, Nielsen NV.

(2004) Prevalence and causes of visual impairment and blindness among

9980 Scandinavian adults: The Copenhagen City Eye Study.

Ophthalmology. 111:1; 53-61.


http://www.ons.gov.uk/about-statistics/harmonisation/index.html

It was based on face-to-face interviews with the household reference

person or another appropriate adult in a sample of households across

Wales. In 2004 and 2008 a property survey was also carried out, which

meant that some respondents received a follow-up visit by a qualified

surveyor to undertake a property assessment of their home.


xviii Bruce I, Baker, M. (2001) Access to Written Information - a Survey of

1000 People with Sight Problems, London: RNIB.

Bruce I, Baker, M. (2003) Employment and unemployment among people

with sight problems in the UK, London: RNIB.

Bruce I, Baker, M. (2005) Transport and mobility for people with sight

problems - the views of 1000 people, London: RNIB.xix Douglas G, Pavey S, Clements B and Corcoran C (2009) Visually impaired people’s access to employment. VISION 2020 UK and University of Birmingham.xx Bruce I, Harrow, J., Obolenskaya, P. (2007) 'Blind and partially sighted

people's perceptions of their inclusion by family and friends', British Journal

of Visual Impairment. 25(1) 68-85.xxi Bajekal M, Harries T, Breman R, Woodfield K. (2004) Review of

Disability Estimates and Definitions. HMSO.xxii GfK NOP Social Research. (2007) Experiences and expectations of

disabled people: a research report for the Office of Disability Issues. ODI:

London.xxiii GfK NOP Social Research. (2007) p39.xxiv GfK NOP Social Research. (2007) p167.xxv DH. (2003) Personal Social Services Physically Disabled and Sensory

Impaired User Experience Survey: What needs doing for 2003-2004. DH.xxvi Tate R, Smeeth L, Evans J, Fletcher A. (2005) The prevalence of visual impairment in the UK: A review of the literature. www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_prevalencereport.doc


http://www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_prevalencereport.doc

http://www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_prevalencereport.doc

Figure 4:17 Living in Wales questions on long-term illness or disability

xxvii Evans J, Fletcher AE, Wormald R, Siu-Woon Ng E, Stirling S, Smeeth L, Nunes M, Breeze E, Bulpitt CJ, Jones D, Tulloch A. (2002) Prevalence of visual impairment in people aged 75 years and above in Britain: results from the MRC Trial of assessment and management of older people in the community. Br J Ophthalmology, 86:795-800.xxviii Collingwood A, Brown V and Smith R. (2010) Towards Better Design:

An Evaluation of the Pilot Study. NatCen: London.xxix http://www.ic.nhs.uk/statistics-and-data-collections/social-care/adult-

social-care-information/people-registered-as-blind-and-partially-sighted-

2008-england xxxhttp://www.ic.nhs.uk/services/social-care/social-carecollections/

collections-2011xxxihttp://www.ic.nhs.uk/statistics-and-data-collections/primary-care/eye-

care/general-ophthalmic-services-activity-statistics-for-england-and-wales-

year-ending-31-march-2010xxxii http://www.ic.nhs.uk/statistics-and-data-collections/primary-care/eye-

care xxxiii PS Ducket et al. (2010) The opinions of people with sight loss on visual

impairment research: study three. Thomas Pocklington Paper: London.xxxiv Smith N and Keyte R. (2008) The Disability Discrimination Act: Analysis

of data from the ONS Omnibus Survey 1996-2006. ODI.xxxv Robertson J and Emerson E. (2010). Estimating the number of people with co-occurring vision and hearing impairments in the UK. Centre for Disability Research.xxxvi WHO (2007) International Statistical Classification of Diseases and

Related Health Problems.10th Revision. Version for 2007


http://www.ic.nhs.uk/statistics-and-data-collections/primary-care/eye-care

http://www.ic.nhs.uk/statistics-and-data-collections/primary-care/eye-care

http://www.ic.nhs.uk/statistics-and-data-collections/primary-care/eye-care/general-ophthalmic-services-activity-statistics-for-england-and-wales-year-ending-31-march-2010



http://www.ic.nhs.uk/services/social-care/social-carecollections/collections-2011

http://www.ic.nhs.uk/services/social-care/social-carecollections/collections-2011

http://www.ic.nhs.uk/statistics-and-data-collections/social-care/adult-social-care-information/people-registered-as-blind-and-partially-sighted-2008-england



A showcard was used as a prompt for the following question. It was used with the response options reversed for half of the sample to avoid order affects (where respondents are more likely to select items from the top of a list than from lower down).

Figure 4:18 Living in Wales questions on type of disability or impairment

http://apps.who.int/classifications/apps/icd/icd10online/ xxxvii Robertson J and Emerson E. (2010). Estimating the number of people

with co-occurring vision and hearing impairments in the UK. Centre for

Disability Research. p18.xxxviii Nazroo J, Zimdars A. (2010) Social inclusion, social circumstances and

the quality of life of visually impaired older people. Pocklington Trust

research report.


http://apps.who.int/classifications/apps/icd/icd10online/

1.26.2 Visual impairment prevalence estimates Overall, 1.7% of people reported that they had a long-term illness or

disability which was impairment related. This equates to 8.3% of people

with an illness or disability. 8.8% of respondents reported being registered

as disabled or vision impaired.

1.26.3 Methodological issues It is interesting that a question was included that made reference to

being registered vision impaired with the council or social services.

However, it was unfortunate that the coding of this was not

disaggregated from that of being ‘a disabled person’ as this. [check

on plans to do this in the National Survey for Wales.]

Show card – is a visual prompt.



I had that 8.6% of respondent visually impaired at Q46. Were are these stats from?

1.26.4 Study contact and further information

wales.gov.uk/about/aboutresearch/social/ocsropage/living-wales/?lang=en

wales.gov.uk/about/aboutresearch/social/ocsropage/

nationalsurveyforwales


http://wales.gov.uk/about/aboutresearch/social/ocsropage/living-wales/?lang=en

http://wales.gov.uk/about/aboutresearch/social/ocsropage/living-wales/?lang=en

1.27 Low Income Diet and Nutrition Survey 2005The Low Income Diet and Nutrition Survey (LIDNS) was commissioned to

provide robust, nationally representative, baseline data on food

consumption, nutrient intake and nutritional status and factors affecting

these in low-income/materially-deprived consumers. It uses, therefore, not

a sample of the whole population, but only of people living in low-income

households.

Data were collected between 2003 and 2005 and the survey report was

published in July 2007. The survey included over 3,700 adults and children

throughout the UK and had a number of components. It collected detailed

quantitative information on food consumption, physical measurements (e.g.

height, weight, blood pressure), and a blood sample. Finally, information

on socio-economic, demographic and lifestyle characteristics was collected

in a detailed interview and assessments of physical activity and oral health

were made by questionnaire.

Details of medications currently taken and reasons for taking medication

are collected. These are coded according to the British National Formulary.


Figure 4:19 LIDNS questions on long-standing illness, disability or infirmity

Heal“Do have any long-standing illness, disability or infirmity? By long-standing I mean an illness that you have has had over a period of time or that is likely to affect you over a period of time.”1 Yes2 No

HealT (ASK IF (Heal = Yes))“What is the matter with you?”SPECIFY

Limit


“Does this illness or disability (Do these illnesses or disabilities) limit your activities in any way?”1 Yes2 No

LimitShp (ASK IF (Limit = Yes))“Does this illness or disability (Do these illnesses or disabilities) limit you or prevent you from shopping?”1 Limits2 Prevents3 Neither

LShpHow (ASK IF ((LimitShp = Limits) OR (LimitShp = Prevents)))“Can you tell me how you are limited/prevented from shopping?INTERVIEWER: CODE ALL THAT APPLY”1 Difficulties with walking2 Problems with sight3 Cannot carry (heavy) shopping4 Gets tired easily5 Other difficulties

LimiPrep“Does this illness or disability (Do these illnesses or disabilities) limit you or prevent you from preparing food?”1 Limits2 Prevents3 Neither

LPrepHow (ASK IF ((LimiPrep = Limits) OR (LimiPrep = Prevents)))“Can you tell me how you are limited/prevented from preparing food?INTERVIEWER: CODE ALL THAT APPLY”1 Difficulties with hands (eg. chopping, peeling, lifting)2 Difficulties with walking3 Difficulties with standing4 Problems with sight5 Chronic ill-health (e.g. MS, depression)6 Gets tired easily7 Other difficulties

1.27.2 Visual impairment prevalence estimates What is interesting about the LIDNS questions is that they allow a

prevalence of the impact of impairment on ability to undertake tasks. 1.5%

of people in low income households reported that problems with their


eyesight limited their ability to do food shopping, and 1% of people said it

impacted on their ability to prepare food.

1.27.3 Methodological issues Coding of reason for medications only included heart problem or

high blood pressure.

BNF codes not labelled.

1.27.4 Study contacts and further informationBeverley Bates and Caireen Roberts, National Diet and Nutrition Survey

directors, NatCen.




1.28 National Diet and Nutrition Survey (NDNS) 2008-9NDNS is a survey of the food consumption, nutrient intakes and nutritional

status of people aged 1.5 years and older living in private households. The

survey is carried out in all four countries of the United Kingdom (UK) and is

designed to be representative of the UK population. The Food Standards

Agency (FSA) commissioned it, with a contribution to funding from the

Department of Health. The programme is carried out by a consortium of

three organisations: The National Centre for Social Research (NatCen),

MRC Human Nutrition Research (HNR), based in Cambridge and the

Department of Epidemiology and Public Health at University College

London Medical School (UCL). The Northern Ireland Statistics and

Research Agency (NISRA) carry out fieldwork in Northern Ireland.

Similarities to the LIDNS, but with variables updated and based on a

sample drawn from the whole population and not just low-income

households.


1.28.2 Visual impairment prevalence estimates The archived dataset contains data for 1017 adults and children up to age

64. As for LIDNS, NDNS includes questions that allow a prevalence of the

impact of impairment on ability to undertake tasks: the impact that

problems with their eyesight had on their ability to do food shopping, or

prepare food. In an advance on the LIDNS questions, NDNS

disaggregated responses into whether the impairment ‘limits’ or ‘prevents’

the tasks.


1.28.3 Methodological issues Coding of reason for medications only included heart problem or

high blood pressure.

BNF codes ARE labelled.

1.28.4 Study contacts and further informationBeverley Bates and Caireen Roberts, National Diet and Nutrition Survey

director and nutritionist, Health and Wellbeing Team, NatCen.




1.29 Life Opportunities Survey (LOS) 2010While the Life Opportunities Survey (LOS) is a new large-scale survey of

disability, its sample is not restricted to disabled people. It is the first major

social survey in Great Britain to explore disability in terms of social barriers

to participation, rather than only measuring disability in terms of

impairments or health conditions. LOS is conducted by the Office for

National Statistics, on behalf of the Office for Disability Issues (ODI).

LOS is a longitudinal survey. This means it will track the experiences of

disabled people over time through key life stages. It compares the

experiences of people with and without impairments across a range of

areas, including education and training, employment, transport, leisure,

social and cultural activities, and social contact. LOS is able to produce a

variety of estimates based on different definitions of disability.

18,000 adults aged 16 and over were interviewed in 2009/2010. This was

the first half of wave one data collection. A full wave one report will be

published in Autumn 2011, and eventually the dataset will be made publicly

available for analysis.

1.29.1 Visual impairment questions asked The LOS questionnaire was developed using the International

Classification of Functioning, Disability and Health (ICF) as a model to

classify impairments. The impairment section of the questionnaire includes

a series of questions relating to any difficulties respondents experienced

across a wide range of functions, including seeing.

Respondents are asked if they experience any difficulty in a particular area

of functioning (e.g. seeing). Respondents then provide information across

each area about the severity of the difficulties they have in relation to

performing specific activities (ranging from no difficulty through mild,


moderate, severe and, for some areas, complete).

Finally they are asked how often, if at all, that the amount or kind of

activities that they can do are reduced or affected, detailing the frequency

with which their activities are limited (never, rarely, sometimes, often, and

always).

A respondent is defined as having an impairment if they indicated that they

experience either moderate, severe or complete difficulty within at least

one area of physical or mental functioning, and certain activities are limited

in any way as a result.

A similar set of impairment screener questions are used in the Northern

Ireland Survey of Activity Limitation and Disability (NISALD). The relevant

questions included in LOS are in Figure 4.20

Figure 4:20 LOS questions on sightIVision Do you have any difficulty seeing, or wear glasses or contact lenses?

(1) Yes

(2) No

SeeClo APPLIES IF: IVision = Yes SHOWCARD R1 (With your glasses or contact lenses) do you have any difficulty seeing

ordinary newsprint at arm’s length?

SHOWCARD

(1) No difficulty

(2) Mild difficulty

(3) Moderate difficulty

(4) Severe difficulty


(5) Cannot do

SeeDis APPLIES IF: IVision = Yes (With your glasses or contact lenses) do you have any difficulty clearly

seeing the face of someone across a room, that is from 4 metres or 12 feet

away?

SHOWCARD

(1) No difficulty

(2) Mild difficulty

(3) Moderate difficulty

(4) Severe difficulty

(5) Cannot do

SeeLim APPLIES IF: SeeDis >1 OR SeeClo > 1 How often does this limit the amount or kind of activities that you can do?

SHOWCARD

(1) Always

(2) Often

(3) Sometimes

(4) Rarely

(5) Never

LOS classifies a respondent as having a ‘visual impairment’ if:

They report having moderate, severe difficulties or complete lack of

function in regards to seeing at either SeeClo or SeeDis; AND,

They report that this difficulty limits their daily activities (i.e. SeeLim=

rarely, sometimes, often or always).

Prior to these questions, LOS also contains a question to capture whether

respondents have any long-term impairments or disabilities. Respondents

who answer yes to this question are asked an additional question on how

their impairment impedes their functioning.


Figure 4:21 LOS questions on long-term impairments and disabilityHealthDo you have any long-standing physical or mental impairment, illness or disability? By 'long-standing' I mean anything that has affected you over a period of at least 12 months or that is likely to affect you over a period of at least 12 months. (1) Yes (2) No

DisDif APPLIES IF: Health = Yes Does this/Do these health problem(s) or disability(ies) mean that you have substantial difficulties with any of these areas of your life? Please read out the numbers from the card next to the ones which apply to you.

INTERVIEWER: Probe: Which others? (1) Mobility (moving about) (2) Lifting, carrying or moving objects (3) Manual dexterity (using your hands to carry out everyday tasks) (4) Continence (bladder & bowel control) (5) Communication (speech, hearing or eyesight) (6) Memory or ability to concentrate, learn or understand (7) Recognising when you are in physical danger (8) Your physical co-ordination (e.g. balance) (9) Other health problem or disability (10) None of these

The codeframe used at DisDef classifies respondents by broad types of

functional impairment. It does not have a specific code for problems with

vision as problems with eyesight are coded as problems with

‘Communication’. Therefore these questions cannot be used to estimate

prevalence of visual impairments specifically.


This section will report on the following:


1. The number of respondents who reported some difficulty with their

sight, or that they needed to wear glasses or contact lenses

(IVision=Yes).

2. The number of respondents who reported having some difficultly

seeing (close up or distance) with glasses on (SeeDis=2-5, or See=

2-5)

3. The number of respondents who fell into LOS’s definition of having a

visual impairment.

In total 67.1% of respondents reporting having difficulties with sight or

using glasses or contact lenses. Prevalence rates by age groups and sex

are shown in Tables 4.17 and 4.18.

Table 4:17 Prevalence of ‘difficulties with sight’ / uses glasses or contacts, by age

Age 16-19 20-29 30-39 40-49 50-59 60-69 70-79 80+ TOTAL% % % % % % % %

Difficulties with sight/

uses glasses or

contacts

28.3 37.0 41.7 60.1 89.0 92.7 91.8 92.6

Base 1097 2346 2757 3251 2939 2766 1870 993 18019

Table 4:18 Prevalence of ‘difficulties with sight’ / uses glasses or contacts, by sex


Difficulties with sight/ uses glasses or contacts 63.5 70.3 67.1Base 8476 9543 18019

Respondents who reported having difficulties with their sight initially were

asked two follow-up questions on whether, with glasses, they had any

difficulties reading newspaper print or seeing a face across a room.


In total 9.9% respondents reported having difficulties at seeing at these

follow-up questions. 4.1% of respondents reported they had at least mild

difficulties seeing a face across a room. 8.9% respondents reported having

at least mild difficulties reading a newspaper held at arms length.

Table 4:19 Prevalence of reporting difficulties in seeing things up close and at distance, by age

Age 16-19 20-29 30-39 40-49 50-59 60-69 70-79 80+ TOTAL% % % % % % % %

Difficulty reading a

newspaper2.7 3.6 4.0 7.7 11.3 10.2 14.1 25.1

Difficulty seeing a

face across a

room

1.5 2.3 1.5 2.7 3.6 4.9 7.5 15.3

Difficulties with either

of the above

3.3 4.7 4.6 8.3 12.1 11.5 16.0 26.8

Base 1097 2346 2757 3251 2939 2766 1870 993 18019

Table 4:20 Prevalence of reporting difficulties in seeing things up close and at distance, by sex


Difficulty reading a newspaper 8.4 9.3 8.9Difficulty seeing a face across a room 3.6 4.4 4.1Difficulties with either of the above 9.2 10.5 9.9Base 8476 9543 18019

Finally, 3.3% of respondents met LOS’s definition of having a visual

impairment (that is, they rated themselves at having moderate (or worse)

difficulties seeing (either when looking at things close up or at distance)

and stated that this limited the activities they do.)


Prevalence rates of visual impairment using this definition are shown in

Tables 4.21 and 4.22, by age group and sex.

Table 4:21 Prevalence of visual impairment by age, using LOS definition

Age 16-19 20-29 30-39 40-49 50-59 60-69 70-79 80+ TOTAL% % % % % % % %

LOS definition of visual

impairment

0.5 1.2 1.2 2.4 3.6 3.2 6.0 15.0

Base 1097 2346 2757 3251 2939 2766 1870 993 18019

Table 4:22 Prevalence of visual impairment by sex, using LOS definition


LOS definition of visual impairment

2.9 3.7 3.3

Base 8476 9543 18019

1.29.3 Methodological issues Inclusion of impaired function/limiting activities

Different definitions naturally yield results:

SeeDis and SeeClo ask respondents to rate their difficulties rather

than give a flat Y/N

LOS’s question on seeing a face across a room is clearer than WHS

Q- any room for comparison.

Compare VisionI with APMS- BOTH include PROBLEMS CORRECT

BY SIGHT BUT VERY DIFFERENT RESULTS.

No information collected on type of condition.

Collects information of types of impairment and severity.

Also asks question on disability- some respondents classified by

LOS as having a visual impairment did not classify themselves as



FRS disability module asks similar Qs BUT Y/N can we do anything with this?

Sally McManus, 14/09/11,

This section is not yet complete.

having a disability at ‘Health’. This indicates that even moderately

severe visual problems ones that impact on activities are not

necessarily considered as disabilities: the disability approach to

capturing visual impairments could lead to underestimates when

respondents are routed by these questions.

1.29.4 Study contacts and further informationJoanna Bulman and Ian O’Sullivan, Life Opportunities Survey (LOS), ONS

http://www.statistics.gov.uk/statbase/Product.asp?vlnk=15386


https://webmail.natcen.ac.uk/owa/redir.aspx?C=1c9a22e032d04914907a9375265ca3d7&URL=http%3A%2F%2Fwww.statistics.gov.uk%2Fstatbase%2FProduct.asp%3Fvlnk%3D15386

1.30 Understanding Society 2010/11

Understanding Society is a longitudinal survey of the socio-economic

circumstances and attitudes of 100,000 people in 40,000 British

households. It is funded by the Economic and Social Research Council

(ESRC), and run by the Institute for Social and Economic Research (ISER)

with fieldwork undertaken by NatCen. The sample is drawn from the whole

population, and being longitudinal it will yield data for examining people’s

longer term occupational trajectories; their health and well-being, financial

circumstances and personal relationships.

It has an interdisciplinary focus. The study will capture biomedical data on

20,000 participants and place this alongside rich social histories, helping

us weigh the extent to which people's environment influences their health.

So far only the wave 1 year 1 data is on the archive, and for the general

population sample only (so no year 2 data and no ethnic minority boost

data yet). Responses collected from proxy respondents have been

excluded from this analysis.


Figure 4:22 Understanding Society questions HEALTHDo you have any long-standing physical or mental impairment, illness or disability? By 'long-standing' I mean anything that has troubled you over a period of at least 12 months or that is likely to trouble you over a period of at least 12 months.1. Yes2. No

DisDif {IF Health = 1}Does this/Do these health problem(s) or disability(ies) mean that you have substantial difficulties with any of these areas of your life? INTERVIEWER: Probe: Which others?


CODE ALL THAT APPLY1. Mobility (moving around at home and walking)2. Lifting, carrying or moving objects3. Manual dexterity (using your hands to carry out everyday tasks)4. Continence (bladder and bowel control)5. Hearing (apart from using a standard hearing aid)6. Sight (apart from wearing standard glasses)7. Communication or speech problems8. Memory or ability to concentrate, learn or understand9. Recognising when you are in physical danger10. Your physical co-ordination (e.g. balance)11. Difficulties with own personal care (e.g. getting dressed, taking a bath or shower)12. Other health problem or disability96. None of these

1.30.2 Visual impairment prevalence estimates In total, 3.2% of respondents reported having substantial difficulties with their sight at DisDif. Prevalence rates of respondents reporting difficulties with their sight as are shown, by age groups and sex, in Tables 4.23 and 4.24.

Table 4:23 Prevalence of respondents reporting difficulties with sight by age group in Understanding Society

Age 16 -19 20 -29 30 -39 40 -49 50 -59 60 -69 70 -79 80+ TOTAL% % % % % % % %

Difficulties with sight at DisDif

0.6 0.8 1.4 1.8 3.1 4.8 7.3 14.1

Base 1324 3179 3865 4166 3529 3227 1979 962 22231

Table 4:24 Prevalence of Prevalence of respondents reporting difficulties with sight by sex in Understanding Society


Difficulties with sight at DisDif 3.0 3.3 3.2Base 9692 12539 22231


1.30.3 Methodological issues Rely on routing from a disability question.

Asked for ‘substantial’ difficulties- not clear what this means.

Unlike HSE/ SHeS provides a prompted list of types of impairments

related to capacity instead an open question on condition. (Does not

appear to influence prevalence estimates).

Specific instruction to exclude glasses.

1.30.4 Study contacts and further informationAnne Connely and Richard Boreham, NatCen.

http://www.understandingsociety.org.uk/


http://www.understandingsociety.org.uk/

4 Comparisons between surveysThe aim of this section is to compare how questions varied between

surveys and the influence this had on the profile of visual impairment

produced. It will do this by considering the:

1) five broad types of measure identified, and

2) varying inclusion and exclusion criteria applied to each question.

Throughout this section results from different surveys will be compared and

implications for data users discussed.

1.31Types of measures identifiedOverall the review found five main types of measure were being used to

collect data on visual impairment in national social surveys. These were:

1. Questions on disability and health conditions (with eye

conditions and visual impairment captured only as a follow-up

question about ‘type of disability’)

2. Questions about quality of sight and seeing (such as ‘do you

have any difficulties seeing?’).

3. Direct questions about the presence of specific ocular conditions

4. Questions on visual capability in particular contexts (whether

respondents have any difficulties seeing specific things under certain

conditions, for example the face of friend across the street).

5. Questions that ask respondent to rate their overall vision on a scale (for example, ranging from excellent to poor).

These different question types, including their strengths and weaknesses,

are discussed in more detail in the following sections.


1.31.1 Questions on disability and health conditions

The most common form of survey data found on visual impairment was

collected using items that ask about the presence of a range of ‘disabilities’

and ‘health conditions’. These questions were typically found as part of a

‘general health’ module within the questionnaire. Within this category there

were three separate formats the question could take:

1) A routed question with an open follow-up: Respondents were first

asked if they had a health condition or disability. Only those who answered

‘yes’ were routed to an open follow-up question on what type of health

condition they had. This approach was used in HSE, SHeS, WHS, NDNS

and the FRS disability follow-up.

2) A routed question with a prompted list to follow-up. Respondents

were first asked if they had a health condition or disability. Only those who

answered ‘yes’ were then asked a closed follow-up question where they

had to pick types of impairment from a prompted list of answer categories.

This approach was used in LOS, Understanding Society, FRS, Living in

Wales and FACs.

3) A single prompted list. Respondents were asked a single question on

whether they had any of the ‘health conditions’ shown on a card. This

approach was only used in APMS.

A comparison of the overall prevalence of ‘visual impairment’ derived using

the questions in six of the surveys is shown in Figure 5.1. FRS, FRS

disability survey, FACs, and NDNS were excluded because they are not

directly comparable (due to sample composition, and issues with question

wording and sample-size).


Figure 5:23 Prevalence rates of visual impairment in general population surveys using disability questions

02468

101214161820

1

Survey

% V

isua

l im

pairm

ent

HSE: Y/N with openfollow-up

SHS: Y/N with openfollow-up

WHS: Y/N with openfollow-up

Living in Wales: Y/Nwith prompted follow-up

Understanding Society:Y/N with promptedfollow-upAPMS: Prompted list

A question that does not rely on routing (that is, a question that is asked of

the whole sample) generates a higher reporting of visual impairment. This

is because respondents who do not consider a problem with their eyesight

to be a ‘disability’ or ‘health condition’ (precise wording of the filter question

varies between surveys) would not be asked the follow-up questions that

are used to identify presence of visual impairment. This could lead to

survey data under-estimating the prevalence of visual impairment.

Conversely, it could also be that reports of mild or correctable visual

impairment are appropriately screened out with the use of a filter question.

APMS was the only survey to use a single prompted list asked of the whole

sample, rather than a routed approach. The Figure 5.1 shows that a much

higher proportion of respondents reported having a visual impairment in

APMS than in the other surveys (17.9%). However, it is likely that this

difference is mainly attributable to another difference in measurement. That

is, in APMS respondents were prompted to include problems corrected by

glasses or contact lenses. All of the other surveys either asked


respondents to exclude problems entirely corrected for by low vision aids

(often ‘glasses or contacts lenses’ is the wording used) or have no

inclusion instructions in this area.

In general it is unclear the extent to which variation in rate of visual

impairment between surveys is due to variations in question framing or to

the different inclusion and exclusion criteria applied (see section X.X). This

could be tested with split run experiments built into a survey design where

only one aspect of the question format is changed and other aspects kept

constant.

Open questions and ICD codingHSE, SHeS and WHS all adopt a similar approach to collecting information

on health conditions and impairments (that is, they use a routed question

with an open follow-up). Verbatim responsens to the open questions were

coded using the World Health Organisation’s International Classification of

Disease (ICD42) code frame.

It was beyond the scope of this scoping review to examine the original

verbatim responses (which will be a mix of symptoms and conditions) and

how these were assigned to ICD codes. This level of detail is not archived

in the UK Data Archive3, but is held securely by survey organisations like

NatCen. HSE coder instructions state conditions like colour blindness and

‘lazy eye’ should be included in the codes relating to visual impairment.

This may not be appropriate, depending on measurement aims.

HSE and SHeS show a similar prevalence of visual impairment using this

method (2.2%-2.3%). However, in WHS a smaller proportion of

respondents reported a visual impairment (0.7%). The lower incidence of

visual impairment could be due to several factors:

3 This is because they could potentially lead to the respondent being identifiable.


Respondents are instructed to provide their main condition only in

WHS. Respondents who have multiple conditions may not consider

a visual impairment to be their main condition. Respondents may be

less likely to mention visual impairments if they are considered less

acute or are considered to be a secondary outcome.

In WHS respondents are only asked to include impairments that

‘limit daily activities or the work they can do.’ Respondents may not

feel that their visual impairment limits their activities.

WHS is a paper self-completion, so visually impaired respondents

may well be less likely to take part.

It is not possible to definitively state which of the above (if any) is the main

factor responsible for the discrepancy between survey results, it is likely

that they all contribute to the low prevalence of visual impairment identified

on WHS.

NDNS (excluded from the comparison analysis due to its small sample

size) uses a similar question approach to that used in HSE and SHeS,

although like WHS it only collects details of the first disability or health

condition mentioned. In NDNS no respondents recorded having a visual

impairment, respondents may have mentioned visual impairments but this

information was never processed as it was not coded as the primary

condition. This suggests that where open follow-up questions are used, it is

important that respondents are able to report multiple conditions and that

all conditions should be coded for analysis.

Prompted lists on functioningBoth FRS and LOS used a prompted list that aimed to establish what

areas of functioning were impaired, rather than what types of conditions

respondents had. The prompted lists, used in both FRS and LOS, are

provided below.


Survey: FRS{If Health=Yes}DisDif Does this/Do these health problem(s) or disability(ies) mean that you have substantial difficulties with any of these areas of your life? Please read out the numbers from the card next to the ones which apply to you. 1: Mobility (moving about) 2: Lifting, carrying or moving objects 3: Manual dexterity (using your hands to carry out everyday tasks) 4: Continence (bladder and bowel control) 5: Communication (speech, hearing or eyesight) 6: Memory or ability to concentrate, learn or understand 7: Recognising when you are in physical danger 8: Your physical co-ordination (e.g. balance) 9: Other health problem or disability 10: None of these

Survey: LOS{Health = Yes}DisDif Does this/Do these health problem(s) or disability(ies) mean that you have substantial difficulties with any of these areas of your life? Please read out the numbers from the card next to the ones which apply to you. (1) Mobility (moving about) (2) Lifting, carrying or moving objects (3) Manual dexterity (using your hands to carry out everyday tasks) (4) Continence (bladder & bowel control) (5) Communication (speech, hearing or eyesight) (6) Memory or ability to concentrate, learn or understand (7) Recognising when you are in physical danger (8) Your physical co-ordination (e.g. balance) (9) Other health problem or disability (10) None of these

Due to the categories used, the functioning questions used in FRS and

LOS are not able to distinguish issues related to vision from those of other

‘communication’ ‘health problems or disabilities’ (although LOS does

include separate questions about vision elsewhere). A more suitable list of


functioning impairments was used in Understanding Society, where vision

is specifically mentioned as an area of functioning.

Inconsistent use of terms: ‘disability’, ‘infirmity’, ‘condition’ The word ‘disability’ is used in many survey questions in a way that is not

informed by a social model understanding of the term. We have used the

word in this review – often, but not always, in quote marks – because it is

part of the common terminology used in general health survey questions.

The questions that collate data on visual impairment use an array of

imprecisely understood words: disability, illness, infirmity, health-problem,

complaint, and health condition appear to be used interchangeably.

Likewise, questions vary in terms of how they define what constitutes a

‘long term’ and ‘long-standing’ condition. Figure 5.2 shows various different

wordings that were used in different surveys.

Figure 5:2 Terms used in questions that collect data on visual impairmentSurveys: HSE 2007 /FACs 2007 /Living in Wales 2008 / LIDNS Do you have any long-standing illness, disability or infirmity? By long-standing I mean anything that has troubled you over a period of time, or that is likely to affect you over a period of time?1 Yes2 No

Survey: SHeS 2008Do you have a long-standing physical or mental condition or disability that has troubled you for at least 12 months, or that is likely to affect you for at least 12 months?1. Yes2. No

Survey: WHS 2007Do you have a long-term illness, health problem or disability which limits your daily activities or the work you can do? (Include problems which are due to old age).


1. Yes2. No

Survey: FRS 2008Do you have any long term health problems or complaints which affectyour everyday activities?1.Yes 2.No

Survey: Understanding Society W1Do you have any long-standing physical or mental impairment, illness or disability? By 'long-standing' I mean anything that has troubled you over a period of at least 12 months or that is likely to trouble you over a period of at least 12 months.1.Yes 2.No

A key issue is whether the wording used influences whether or not

respondents decide to include problems with sight. It is currently not clear

which phrasing, if any, is preferable. Cognitive testing work examines

respondent understanding of survey questions and the thought processes

they go through when deciding how to respond. Such pilot work, using

‘general health’ filter questions with respondents with a range of different

types of visual impairment, would be key to bringing insight to this.

1.31.2 Questions on visual capabilityThe review identified four national social surveys that asked questions

about visual capability. These were:

WHS (one question on being able to see faces at distance)

FRS Disability (a series of questions on being able to see things up

close and at distance)

LOS (two questions, where respondents state to what extent they have

difficulties seeing things close up or at a distance).


NDNS (two questions that looked at whether a visual impairment limited

respondents’ ability to go shopping or to prepare food).

These questions are shown in the box below.

Survey: WHSSEEIs your eyesight good enough to see the face of someone across a room? (Using glasses or contact lenses if you usually wear them)YesYes with difficultyNo

Survey: FRS DisabilitySeeFrnd(Wearing glasses or lenses... ) Do you have difficulty recognising a friend across the road?Yes No

Reading(Wearing glasses or lenses…) Do you have difficulty reading ordinary newspaper print?Yes No

Windows (APPLIES IF SeeFrnd=Yes or Reading=Yes)Can I check, (wearing glasses or lenses...) in a room during daytime,can you tell by the light where the windows are?Yes No

Shape (APPLIES IF Windows=Yes)(Wearing glasses or lenses...) Can you see the shapes of the furniture in this room?Yes No

RecFace (APPLIES IF Shape=l)(Wearing glasses or lenses…)


Can you see well enough to recognise a friend if you get close to his or her face?Yes No

ArmLeng (APPLIES IF RecFace~l)(Wearing glasses or lenses... ) Can you see well enough to recognise a friend who is an arms length away?Yes No

Headline (Wearing glasses or lenses... )Can you see well enough to read a newspaper headline?Yes No

LargePrt (APPLIES IF Headline=l)(Wearing glasses or lenses... )Can you see well enough to read a large print book?Yes No

Room (APPLIES IF LargePrt=l)(Wearing glasses or lenses… )Can you see well enough to recognise a friend across the room?Yes No

Survey: LOSSeeClo (With your glasses or contact lenses) do you have any difficulty seeing ordinary newsprint at arm’s length? (1) No difficulty (2) Mild difficulty (3) Moderate difficulty (4) Severe difficulty (5) Cannot do

SeeDis


(With your glasses or contact lenses) do you have any difficulty clearly seeing the face of someone across a room, that is from 4 metres or 12 feet away? (1) No difficulty (2) Mild difficulty (3) Moderate difficulty (4) Severe difficulty (5) Cannot do

Due to the fact that the questions differ (and that the FRS Disability survey

comprised a very different sample), it is not possible to directly compare

the results from these four surveys. However, it is possible that the FRS

Disability questions and the LOS questions may be more useful as they:

1) Contain fewer ambiguities than the WHS question

2) Collect a greater range of information (capturing both seeing

things close up and seeing things at a distance)

3) Collect details to gauge the severity of the limitations described.

In WHS more respondents reported having difficulty seeing using this

approach than with the open question on disability type (see Section 4.3).

One overarching question on ‘difficulty seeing’ or use of ‘glasses or contact

lenses’ was identified. This question was in LOS and is shown below.

IVision Do you have any difficulty seeing, or wear glasses or contact lenses?

1. Yes

2. No

The proportion of respondents who reported difficulty in seeing at this

question was the highest across all the surveys reviewed (67.1%). This is

likely to be due to the fact respondents are directly asked whether they


wear glasses or contact lenses. Furthermore, the context of glasses use is

not specified and implies inclusion of occasional use of LVAs such as for

reading, computer use or the cinema. In contrast, in the same survey only

9.9% of respondents reported difficulty seeing things using the visual

capability measures (see Section 4.12).

Interestingly, the general question in LOS produced a higher prevalence

rate than the APMS disability question that provided a prompted list of

health conditions including the item ‘cataracts/eyesight problems (even if

corrected with glasses or contacts).’ For the APMS question only 17.6% or

respondents reported having problems (even if corrected with glasses or

contacts) in the last 12 months. This suggests that the use of the word

‘problems’ can alter respondents’ understanding of the question.

Respondents may be more likely to report the fact they wear glasses than

that they have a problem with their eyesight that is corrected by glasses.

1.31.3 Questions on specific ocular conditionsOnly one of the surveys reviewed, ELSA, contained measures that

captured specific ocular conditions. This included specific measures on

whether respondents had been diagnosed with cataracts, macular

degeneration, glaucoma, and diabetic eye disease.

ELSA only collects data from people aged 50 and over. However, both

HSE and SHeS contain sufficient numbers of older respondents for

comparisons to be made with the data collected at ELSA. Table 5.1 and

Figure 5.3 show how visual impairment measures vary among people aged

50 and over (using either an open question on disability (HSE, SHeS) or

specific prompts for ocular conditions (ELSA)).


Table 5:25 Visual impairment measures among older people, by survey and age groupSurvey Visual impairment measures 50-59 60-69 70-79 80-89HSE 2007 ICD code 9 or 10 reported at

‘IllsTxt’ 1.2% 2.3% 4.8% 11.4%Base 1094 1077 727 333

SHeS 2008 ICD code 9 or 10 reported at ‘IllsM’ 1.6% 2.8% 4.2% 9.9%Base 1153 1095 783 332

ELSA W4 Glaucoma, Macular degeneration, diabetic eye

disease or cataracts reported at ‘Heop’ 6.6% 15.7% 34.3% 41.6%

Base 2899 3506 2358 982

Figure 5:24 Prevalence of visual impairment, by survey and age group

Within equivalent age bands reports of ocular conditions are much higher

in ELSA then in HSE or SHeS (despite the fact HSE and SHeS have

broader inclusion criteria, as any type of eye condition could have been

reported). This suggests that respondents are much more likely to report

the presence of ocular conditions when specifically asked about it. In HSE

and SHeS rates of visual impairment are likely to be underestimates, as


the measures are not specific enough. Respondents are more likely to

report ocular conditions if they are prompted by a specific example, rather

then asking about ‘illness,’ ‘disability’, ‘infirmity’, or ‘health conditions’ in

general.

Subjective data collected during the interviews can be seen as

unprompted, prompted or observed measures. xxxix The latter is based on

interviewer observations, such as the interviewer coding the reason that a

self-completion module was not completed was because of sight problems.

This ties in with reporting of findings from Network 1000, which

identified the most useful measure in one set of analyses as being a

prompted question that directly asked the participant about difficulties that

they have with seeing.

1.31.4 Questions on self-rated eyesightOne question was identified where respondents were asked to rate their

own eyesight overall (on a scale from excellent to poor). The question was

on ELSA and therefore not asked of the general population. As discussed

in Section 4.5, it is very interesting to note that the majority of people who

reported having an ocular condition at ELSA still rated their eyesight highly

(39.3% of people with an ocular condition rated their eyesight as ‘good’,

21.9% rated their eyesight as ‘very good’, and 7.8% rated their eyesight as

‘excellent’). This suggests that a measure of self-rated eyesight is

understood by respondents to mean something quite distinct from

presence of an ocular condition. Given the two questions are asking

different things, one should never be used as a substitute for the other. For

example, a question on self-rated eyesight should not be used as a proxy

measure of the presence of ocular conditions.


1.32 Inclusion and exclusion criteriaIn addition to different question wordings and formats, there was also

variation in terms of inclusion and exclusion criteria. The two main areas of

related to:

Use of low vision aids

Whether conditions ‘limit day to day activities’.

1.32.1 Use of low vision aids (LVAs)There was variation in the instructions to respondents on whether or not

low vision aids should be taken account of. Some questions stated to:

Exclude eye problems that were fully corrected by ‘glasses and

contact lenses’

Include problems corrected by glasses

Some gave no inclusion criteria in relation to this.

APMS, was the only one to indicate that problems with eyes that were

correctable should be included. As discussed in Section 5.1, the

prevalence of reporting visual impairment was far higher for this survey

(17.6%) than for the HSE and SHeS (2% to 3%). Low vision aids were

almost exclusively defined as ‘glasses or contact lenses’, with other types

not mentioned. Where surveys did not indicate whether or not correctable

sight loss should be included, it is hard to know how respondents

interpreted the question. Furthermore, where the question was one to be

read out by the survey interviewer (rather than administered by self-

completion) the reference to low vision aids may not in practice have been

read out at all, especially if the respondent was not clearly wearing glasses

at the time of the interview. The reference to ‘glasses and contact lenses’

was often given in the question text in parenthesis, which indicates to the

interviewer that it only needs to be read out ‘if necessary’.


1.32.2 Whether conditions are ‘limiting’As also discussed in Section 5.1, WHS data produce a lower prevalence of

visual impairment (0.5%) than HSE and SHeS despite using the same ICD

code frame. One of the factors impacting on this is likely to be the fact that

WHS specifies only including conditions that ‘limit your daily activities or

the work you can do.’ The difference in rate however is likely to also result

from the fact that the question specified inclusion of ‘one illness only.’


5 Conclusions Most social surveys in Britain do not collect information on visual

impairment. Among those that do, there is great variation in the questions

used. They employ a range of different measurement constructs (including

type of impairment or condition, capability and function, symptoms, and

general self-rating). Different questions generate very different rates of

‘visual impairment’.xl Despite this, we (and Robertson and Emerson) find a

reassuring amount of consistency where similar questions have been

used.xli

With greater consistency in questions used on different surveys it would be

easier to combine surveys to produce large samples of visually impaired

people for analysis. However - and more importantly - many of these

questions are likely to be very poor predictors of visual impairment as

diagnosed by means of more objective measures.

There are some plans to reduce the extent of variation in disability

questions used and to improve their validity. The Office of Disability Issues

(ODI) has been involved in an on-going project with ONS to develop a

harmonised suite of disability questions to measure the prevalence of

disability as defined by the Equality Act. The questions may well present

an improvement in how ‘disability’ is measured in surveys, and may

address some of the inconsistency there is in the terminology used (with

illness, infirmity, complaint, impairment and disability widely used

xl Mont D. (2007) Measuring Disability Prevalence. Washington DC. USA:

The World Bank.xli Robertson J and Emerson E. (2010). Estimating the number of people

with co-occurring vision and hearing impairments in the UK. Centre for

Disability Research.


interchangeably). However, it does not seem to address many of the

problems that this review has identified in the measurement of visual

impairment.

Visual impairment measurement on social surveys suffers from a lack of

priority accorded the subject by ‘mainstream’ research commissioners and

survey managers. It is seen as a specialist, rather than generalist, subject

area. Further, mainstream survey coverage of the subject is unlikely to be

able to provide the level of accuracy and detail that many users of this data

might require, such as an accurate assessment of visual acuity. Quite

considerable time and training would be required to include objective

measures on surveys. Piloting of such measures (for example on the

Better Design Survey) have not yet been fully successful.

An ambitious recommendation would be to examine the suitability of a two-

phase survey design, where brief screening questions are included on a

national social survey, followed by a phase two clinican administered

assessment with those screening positive. Such an approach is used

widely in health research, for example on studies of dental health and

psychiatric morbidity.

There is great competition for space on national general population

surveys. In the current climate, with several national survey programmes

having been suspended or their questionnaires shortened to save costs,

this problem is compounded. Much research commissioning has moved

away from funding the collection of primary data and towards secondary

analysis of existing datasets. However, very specific data on visual

impairment exist that are currently hard to access. Details on conditions

are often either a) not collected, b) not fully coded, c) over aggregated, d)

not reported on, or e) not even archived. We recommend a review of

archival practice to encourage the secondary analysis of survey data on

this topic. There is a movement towards fewer variables being archived


due to the data security risks of disclosure resulting from variables being

archived in combination. However, a common sense approach is required

to ensure that these risks are not overstated.

‘Wellbeing’ is currently one of the few ‘growth areas’ in social research.

Demonstrating a strong link between visual impairment and wellbeing will

be key to admitting this topic to the mainstream research and policy

agenda, alongside publicising the fact of the growing proportion of the

population who will be affected in the coming decades.

The key methodological limitations to existing questions vary between

surveys, but include:

The use of a ‘disability’ filter question

The collection of one primary condition

Inconsistency and ambiguity around inclusion LVAs /correctable

sight problems

Restriction to ‘limiting’ conditions

Lack of respondent awareness about diagnoses and causes

Lack of clarity about the distinction between conditions, symptoms,

and functional impairments.

With the wider (but very much incomplete) move across social research

and policy from a medical to a social model of disability, information on

conditions will be collected less and less. But the focus may shift towards

examining barriers that are amenable to policy, and to research that better

addresses social equality issues.

A key issue to communicate to the ‘mainstream’ survey research world is

what is the primary research need. If it to identify the population of people

who’s day-to-day lives are affected by sight loss, then the key

recommendation is to include a non-filtered question that includes a

specific prompt. This should be administered face to face rather than in a


self-completion. If the key issue is to identify what proportion of the

population has particular ocular conditions or to understand the causes of

sight problems, then it may be that administrative data sources are

preferable. Great improvements are underway in the collection,

management and analysis of administrative datasets, including information

on medications and diagnoses. There is great scope to extend the analysis

of survey-collected information on medication use, and, furthermore, the

analysis of linked survey and administrative data sources such as hospital

episode and mortality statistics.

Administrative data sources, however, tell us very little about the lives of

people: their families, social networks, wellbeing, employment and more.

And it is only general population samples that enable people with sight loss

to be compared with the rest of the population. Survey datasets are also

better than administrative sources for examination of trends, because the

criteria influencing inclusion in administrative sources have been changing.

Better quality general population survey data on visual impairment is

therefore crucial.

We hope that this scoping review will be useful to survey designers and managers; data coders; research analysts; and people in organisations responsible for commissioning or provision of services. This is a draft report and we welcome comments, suggestions and revisions. Please let us know if you would like to take part in a discussion of the findings and in formulating the recommendations.


Appendix A Summary of surveys

Summary table of reviewed surveys, sample and questions.Survey Question type Cover Methods Prev’

%Longstanding ‘illness, disability or infirmity’

Prompts specific ocular conditions

Visual capability

Self-rated quality of eyesight

e.g. Do you have any longstanding illness, disability, or infirmity of any kind?

Type of long-standing illness question

e.g. Has a doctor or optician ever told you that you have cataracts?

e.g. Do you have difficulty reading ordinary newspaper print?

e.g. Is your eyesight ..1.excellent2 very good3 good4 fair5 or poor?

HSE Y/N with open follow-up on specific condition

None Conditions coded with ICD code-frame

2.2%

SHeS Y/N with open follow-up on specific condition

None Conditions coded with ICD code-frame

2.3%

WHS Excludes problems corrected by glasses

Paper self-completion

5.6%4

4 Seeing things at distance only


Y/N with open follow-up on specific condition

Only includes conditions that limit activities

Asks for main condition only

0.7%

APMS Prompted list of condition type (e.g. eyesight problems)

Includes conditions corrected by glasses

17.6%

ELSA None Sample is aged 50+

20.5%

Rating eyesight whilst wearing glasses

Sample is aged 50+

3.6%5

FACs Y/N with prompted list to follow-up (e.g. Difficulty in seeing)

None Sample of parents in receipt of child benefits

0.6%

FRS Y/N with prompted follow-up on how functioning is

None Function measures do not specifically code problems with vision

N/A

5 Rate eyesight as ‘poor’ or state they are registered blind.


impaired

FRS- Disability follow up

Y/N with open follow-up on specific condition


Sample disabled or aged 75+

6.8%

Excludes problems corrected by glasses

Sample disabled or aged 75+

18.4%6

Living in Wales

Y/N Prompted list of condition type (e.g. vision)

None 8.6%CHECK

NDNS Y/N with open follow-up on specific condition

None Conditions coded with ICD code-frame. Only first condition mentioned coded.

0.0%

Small sample: n=459


Captures whether shopping/ food prep is impaired due to ‘problems with sight’

0.2%

Small sample, n=459

LOS Y/N With

None Function measures

N/A

6 Either difficulty seeing things at a distance or up close


prompted follow-up on how functioning is impaired.

do not specifically code problems with vision

Excludes problems corrected by glasses

Rs asked to rate difficulty on a 5-point verbal scale.

9.9 7

As above but only includes moderate difficulties that limit activities

Rs asked to rate difficulty on a 5-point verbal scale.

3.3

Understanding Society

Y/N with prompted list on how functioning is impaired

Excludes problems corrected by glasses.

Function measures include code on ‘sight’

3.2

7 Mild difficulty or greater seeing things close up or at distance.


Appendix B Project team

Project teamNatCen is the UK’s largest independent social research institute, it is non-

profit making and with charitable status. The authors are part of the Health

and Wellbeing Team and the Research Methods Hub at NatCen. NatCen

conducts and analyses many of the key UK national social surveys, and

this study has benefited from the direct input of many of the surveys

managers.xlii

Project advisorsThe project team are survey methodologists and data analysts with an

specific interest in health, disability and wellbeing. However, we are not

experts in visual impairment. We have therefore drawn on experts in the

field (in academia, the charitable sector and in Government departments

and agencies). See Section 1.5 for a list of some of the people who have

contributed.

xlii See http://www.natcen.ac.uk/natcen/pages/or_health.htm.


http://www.natcen.ac.uk/natcen/pages/or_health.htm

Appendix C Suggested further work

SummaryThere are a number of ways in which this initial scoping review could be

developed and extended:

C1 - Include administrative and international data sources, as well as

coverage of child populations.

C2 - Conduct cognitive development work with people with a wide

range of types of visual impairment to explore how they interpret

existing survey questions (including the new harmonised set of

disability questions) and to inform the development of improved

questions and methodological administration.

C3 - Run a split run experiment on a national social survey sample to

test the impact of specific aspects of ‘disability’ question wording.

C4 - Provide a case study of how a visual impairment variable is

constructed, in theory and in ‘warts and all’ practice, and construct an

improved derived variable by recoding raw data from 10,000 Health

Survey for England (HSE) respondents.

C5 - Develop practical guidance on improved question administration,

interviewer instructions, editing guidance and raw data codification,

developed through dialogue with interviewers, data editors and coders,

survey methodologists, survey commissioners and clinical researchers.

C6 - Conduct secondary analyses of the Health Survey for England

(HSE) using descriptive cross-tabulations, multivariate logistic

regression, and other statistical approaches in relation to trends over

the past 12 years, subgroups such as people of working age and

ethnic minorities, and social inclusion, participation and service use.

The available sample includes more than 100,000 people in the

general population..


C7 - Review what further secondary analyses of HSE and other

existing data sources could cost effectively be performed, in particular

in relationship to linked HSE and hospital episode and mortality statistics.

C1 Extend the scope of the review

Include administrative data sources, such as HES and registration, and

identify international examples of best practices. Exclude the population

scope to include children. Focus on identifying and analysing the key

longitudinal data sources available on this topic.

C2 Cognitive development work with visually impaired peopleConduct cognitive development work with people with a wide range of

types of visual impairment to explore how they interpret existing survey

questions (including the new harmonised set of disability questions) and to

inform the development of improved questions and methodological

administration. Cognitive work is ideally place to examined how visually

impaired people actually understand the questions used.

C3 Run a split run experiment Run an experiment whereby a randomly allocated half of the sample are

given one version of a question wording, and the other half are given the

same question but different in only one aspect. The impact of that aspect

of the survey question can then be gauged.

C4 and C5 Developing the HSE coding of visual impairmentAs the primary source of community based prevalence of conditions, it

would be useful to examine the current process of capturing visual

impairment in the Health Survey for England (HSE), and to propose to the

survey team improvements to the future collection and codification of such

data. The question format used on HSE is standard to many other surveys,


so lessons drawn would have wider relevance. Its codification is based on

ICD-10, although in practice data are collected by interviewers and coded

by coders and there is scope for improvement in both.

The present HSE coding approach does not distinguish between eye

pathology and other treatable forms of sight loss such as cataracts (see

Chapter 4 for the coding frame). It also includes a mix of symptoms and

diagnoses, which in part is a reflection of the fact that respondents often do

not know the name of the conditions that they have. Therefore, such work

would seek to generate clearer instructions for field interviewers, a more

useful coding scheme for data coders and practical guidance for research

analysts in interpreting such data.

It would also seek to review whether useful information could be drawn

from the data collected on the HSE nurse visit about all medications

currently taken by respondents. Information drawing on the medication

data could be combined with self-report data to create an additional

derived variable of visual impairment.

A piece of work of this kind would be undertaken alongside the HSE survey

team and would involve:

1) An examination of verbatim responses to questions about long

standing illness, disability or infirmity that are sight-related. This

would include exploring raw data generated from HSE 20078 by

deriving test data, identifying verbatim responses that are sight

related, and establishing how responses are coded using existing

methods and to what extent data it is being multi-coded, and

producing new derived variables of visual impairment based on

HSE 2007 data.

8 As this level of data (the raw verbatim responses provided by respondents and keyed into the laptop by the interviewer) is not publicly archived, we would need internal (NatCen) ethical approval to conduct such analyses, but do not anticipate difficulty in obtaining this.


2) Drawing on wider expertise to review and help identify typologies of

conditions or symptoms or combinations of symptoms (based on

HSE data) that may be considered to constitute ‘visual impairment’.

Generate recommendations for revisions to the coding frame.

3) Revised coding and editing instructions of visual impairments could

be developed for use in future waves of HSE.

4) Produce a new derived variable, which could be used in future

analyses related to sight impairment.

5) Furthermore, the new coding scheme could be used to re-

categorise HSE sight related raw data from 1997 to 2007.

C6 and C7 Secondary analyses of HSE and other survey datasets: trends, subgroups and social inclusionResearch suggests that unregistered individuals with sight loss access

different levels of support and services compared with registered

individuals, and that their general experiences of independence, quality of

life, and community participation are likely to be different.xliii Furthermore,

many factors (other than severity) influence whether or not an individual

becomes registered, and these factors could change with time.xliv,xlv Trends

in the registration rate cannot therefore be relied on to reflect trends in

actual levels of sight loss in the population.

xliii Percival J and Hanson J. (2007) ‘I don’t want to live for the day any

more’: visually impaired people’s access to support, housing and

independence.’ British Journal of Visual Impairment. 25(1):51-67.xliv Bruce, I, Harrow, J and Obolenskaya, P. (2007) ‘Blind and partially

sighted people’s perceptions of their inclusion by family and friends’. British

Journal of Visual Impairment. 25(1): 68-85.xlv Johnson, MRD and Morjaria-Keval A. (2007) ‘Ethnicity, sight loss and

invisibility.’ British Journal of Visual Impairment, . 25(1): 21-31.


In a key piece of research funded by the Pocklington Trust, Gjonça and

Nazroo used survey data to profile visual impairment in England.xlvi Their

study covered older people only and reflected one snapshot in time. This

could be extended by using nationally representative survey data that:

covers the whole adult age range, and

has been collected continuously since 1997.

Secondary analysis could be undertaken of the combined HSE survey

series (using the existing HSE visual impairment variable, although this

could be reviewed if the work outlined above was undertaken). The

analysis could involve a sample of men and women with and without self-

assessed visual impairment generated by combining the HSE 1997 to

2007 datasets. This would provide not only a substantial sample of 2,671

adults aged 16 and over with self reported sight loss, who can be

compared with 107,351 people without sight loss, but also enable trends

over time to be considered by dividing the sample into survey years (see

Figure B1). By including the boost year samples (when older or minority

ethnic people were over-sampled) the number of people with a self-

reported visual impairment in the sample would be over 4,000.

Figure B1 Presence of self-reported visual impairment in adults aged 16+ (HSE core sample 1997-2007)

All adults aged 16+

Survey year

Sample sizeSelf-reported visual impairment Total sample size

N % N

HSE 1997 228 3 8,575HSE 1998 382 2 15,898HSE 1999 189 2 7,797

xlvi Gjonça, E and Nazroo, J. (2006) An investigation of the circumstances

of older people with sight loss: analysis of the English Longitudinal Study of

Ageing. Thomas Pocklington Trust Occasional Paper 9.


HSE 2000 179 2 7,986HSE 2001 410 3 15,638HSE 2002 190 3 7,393HSE 2003 415 3 14,832HSE 2004 176 2 7,465HSE 2005 182 2 7,630HSE 2006 320 2 14,137HSE 2007 151 2 6,882Base 2,671 2 107,351

The analyses could also be run on working age adults, of whom 1,180 in

the dataset have a self-reported visual impairment (see Figure B2).


Figure B2 Presence of self-reported visual impairment in adults of working age 16-65 (HSE sample 1997-2007)

Adults aged 16-65

Survey year

Sample sizeSelf-reported visual impairment Total sample size

N % N

HSE 1997 107 2 7,013HSE 1998 162 1 12,833HSE 1999 84 1 6,303HSE 2000 68 1 6,416HSE 2001 177 1 12,513HSE 2002 83 1 5,970HSE 2003 160 1 11,794HSE 2004 71 1 5,895HSE 2005 73 1 6,118HSE 2006 133 1 11,024HSE 2007 62 1 5,353Base 1,180 1 91,232

Trends in visual impairmentOne aspect of such research would be to examine trends in the prevalence

of visual impairment over time (1997 to 2007) in a representative sample of

non-institutionalised adults across the age range and of those of working

age (16-65) in England. The approach would be similar to that used by Lee

et al. in ‘Trends in Visual Acuity Impairment in US Adults’.xlvii Trends would

be run overall and for men and women separately, and there is scope to

look at trends within some subgroups (e.g. by looking at a rolling average).

Socio-demographic profile

xlvii Lee, DJ; Go´mez-Marı´n, O; Lam, B; et al. ‘Trends in Visual Acuity

Impairment in US Adults: The 1986-1995 National Health Interview Survey’

Arch. Ophthalmol: 122, Apr 2004.


Descriptive cross tabulations could be used to identify the key patterns and

associations between visual impairment and socio-demographic indicators

(including age, sex, socio-economic status, household income, housing

tenure, employment status, being in receipt of benefits and living

arrangements). Ethnic origin could be included as HSE included large

boosts of minority ethnic groups in 1999 and 2004. Data would be

presented both observed and after age-standardisation,xlviii the latter to

enable comparison between people with and without visual impairment

while controlling for different age profiles of different groups. Observed

tabulations are important as they profile the population in an accessible

way and present population-based estimates of level of current need.

Factors associated with visual impairmentRegression analyses could be used to examine associations between

visual impairment and each characteristic, while controlling for all the other

characteristics in the model. So for example, we can see whether there is

an association between ethnicity and visual impairment, after controlling for

age, sex, and the other socio-economic variables in the model.

General health, health conditions and hearing lossSelf-reported general health status among adults with a visual impairment

could be compared with the rest of the general population sample. The

relationship between visual impairment and other physical and

psychosocial health indicators could also be examined, identifying levels of

co-morbidity with other impairments (including hearing loss and general

mental well-being) and the extent to which these limit individuals’ activities

in any way.

Service useDescribe the level and nature of service use among older people with a

visual impairment (including use of community services such as meals on xlviii Age-standardised estimates are used to enable groups to be compared

after adjustment for any differences in their age distributions.


wheels and voluntary workers, use of home help, contact with GP, in and

out patient appointments and hospital stays, and local authority care),

compare with older people without a visual impairment, and describe

changes over time.xlix

Social inclusion and networksExplore some of the associations between visual impairment and

dimensions of social capital including social participation and networks as

measures of social inclusion. The quantity and quality of social interaction

are important components of social capital. We propose various strands of

analysis with this emphasis including perceived social support. Recent

research has investigated perceptions of social support among visually

impaired people and found that this group reported a lack of social

integration within the community compared to the general population (ref).

It would be possible to draw on this work and explore the associations

between visual impairment and levels of perceived social support from

family and friends. HSE also provides two different measures of social

networksl asked of older adults that include ‘contact with family’ and

‘contact with friends’. ‘Contact’ was defined as including how often they

met face to face and how often they spoke over the phone. The analysis

would aim to draw out the level and nature of contact among visually

impaired people, compared to the general population.

Further secondary analyses of HSE might include examining views of the

local environment and ease of access to local amenities among visually

impaired people and exploring postcode level characteristics of

respondents’ neighbourhoods as measured by the Index of Multiple

Deprivation.

xlix The health services questions were asked of adults aged 65 years and

over. HSE 2003 survey did not include this module. l Questions about the nature and level of contact received from family and

friends were asked in HSE 2005.



Notes and References

xxxix Sue Pavey, Sarah Bodsworth, Graeme Douglas, Isabel Clare, and Liz

Hodges (2007) Secondary data analysis with a focus upon the needs of

older people with acquired hearing and sight loss: An analysis of the

‘Network 1000’ and ‘Cambridge’ datasets. Research Report prepared for

Thomas Pocklington Trust as part of the research project “Experiences of

people with both hearing and sight loss”.


Documents

Report Title - VISION UK€¦ · Web viewThis suggests that the use of the word ‘problems’ can alter respondents’ understanding of the question. Respondents may be more likely