The Sight Vol -6 Issue 6

Nepal Optometry Students' Society (NOSS)9th Executive Body

Nepalese Association of OptometristsB.P. Koirala Lions Centre for Opthalmic Studies

Institute of MedicineMaharajgunj, Kathmandu, Nepal

P.O. Box: 8750 Tel : 977-1-4720694 / 4720695 Fax : 977-1-4720142Email : [email protected]

Suraj Upadhyaya(President)

Sarita Manandhar(Vice-President)

Subash Marasini(Member)

Mukund Pant(Member)

Khem Narayan Chalise(Member)

Safal Khanal(Secretary)

Pawan Raj Patel(Treasurer)

An Annual Optometric Journal THE SIGHT Volume 6, Issue 6Published by:

Nepal Optometry Students’ Society, 9th Executive BodyCopyright© Nepal Optometry Students’ Society

Disclaimer

We have tried our best to make this publication errorless and evidence based. Nepal Optometry Students’ Society disclaims all liability and responsibility to any person regarding the events or the consequences that might arise here

forth as a result of reliance to any contents in this publication wholly or partly. Statements published in the journal are attributed solely to the authors as

designated and not the offi cial perspectives of NOSS in any ways.

For enquiries or comments:

Nepal Optometry Students’ Society, NOSSInstitute of Medicine

BPKLCOSP.O Box: 8750

Phone: +977-01-4720694Fax: +977-01-4420142

Email: [email protected]: www.optometrynepal.org.np

The history of optometry can be traced back to the early studies on optics and image formation by the eye. The origin of optometric science dates back a few thousand years BC as evidences of the existence of lenses for decoration have been found. Optometry a primary eye care profession plays an important role in the diagnosis, management, co – management and referral of various eye/ vision related issues. The current scope and dynamism of optometrist in all level of eye care is enormous.

But in Nepal this baby profession requires support and co-ordination from other eye care professionals to fulfi ll the responsibilities it has committed to. The evolution of sub- specialities such as Low vision, Contact lens, Binocular vision, Pediatric optometry, Geriatrics Optometry, Community optometry and occupational optometry and so on has helped the profession to achieve its mission. The major challenges faced by this emerging profession are: standardizing clinical practice, standardizing education, regularizing research, maintaining ethical standards and legalizing practice.

Through “THE SIGHT” we are making a tiny endeavor to strengthen optometry education and practice in Nepal. We have tried our best to make the current issue more scientifi c and informative recognizing the need to update and upgrade different sub-specialties of optometry practice.

We are obliged to all the contributors who have given their valuable time to write the articles. Similarly, we are also grateful to the kindness, encouragement and cooperation given by the people whom we have approached for advertisement. We hope “THE SIGHT” will be readers’ favorite as a vision science journal.

We welcome your feedback and comments. Please let us know how we are doing.

THE SIGHT

Team 2010

AdvisorsProf. Dev Narayan ShahProf. Jeevan Kumar ShresthaMr. Gauri Shankar Shrestha

Chief EditorMr. Suraj Upadhyaya

EditorsMr. Prakash AdhikariMs. Sarita ManandharMr. Safal KhanalMr. Amrit Pokhrel

Financial ManagersMr. Pawan Raj PatelMr. Samir Upreti

Article collectionMr. Rupesh PoudelMr. Samir Upreti Mr. Sudarshan Paudel

Technical TeamMr. Rupesh PoudelMr. Mukunda Pant

Cover DesignMr. Rupesh PoudelMr. Safal Khanal

Printed At:Sigma General Off set PressSanepa, Lalitpur-2Ph.: 5554029Email : [email protected]

THE SIGHT Vol 6, Issue 6, September, 2010

Editorial

Secretarial DeskSafal Khanal

Original Articles

Low Vision in Lumbini Zone Blind School Students: Use of Optical Low Vision Services ---------------------------1Hari Thapa, Manoj Sharma, Bimal Poudyal, Rishi Kant Adhikari and Kavita Dhakwa

Reading in Children with Low Vision ------------------------5Balsam Alabdulkader and Susan J. Leat

Wearing Aid as a Remedy to Headache -------------------- 11Rabindra Adhikary

Profi le of Pediatric Low Vision at Sagarmatha Chaudhary Eye Hospital, Lahan ---------------------------- 14Mahesh Kumar Dev

Agreement of Synaptophore and Prism Cover Test Measurement in Strabismus --------------------------------- 16Raju Kaiti and Ajit Thakur

Review Articles

Post-Graduate Degree in Optometry: Explore the Opportunities---------------------------------------------------- 17Prakash Paudel

Importance of Central Corneal Thickness in Intra Ocular Pressure Measurement ------------------------------ 21Madhu Thapa

Post Keratoplasty Astigmatism- Practical Management ----------------------------------------------------- 22Meenu Chaudhary

Intraocular lenses for Near Vision -------------------------- 26Jit B Ale

Daily Disposable Contact Lenses ---------------------------- 29Vipin Buckshey

Computer Vision Syndrome- New Millennium Disease --- 31M R Bajracharya and Kishor Sapkota

Keratoconus: Meaning and Option Today ---------------- 33Rajesh Wadhwa

A Decade of Optometric Profession in Nepal ------------- 36Subodh Gnyawali

Prescribing Pediatric Refractive Errors ------------------- 38Nabin Paudel

Optometry Ethics and Practice Management Pearls --- 40Himal Kandel

Kids Vision is falling through the Cracks ----------------- 42Michele Marshall

Contact lens Practioners -------------------------------------- 43Dinesh Kaphle

Eye in Methanol Intoxication -------------------------------- 45Sanjay Marasini

Behavioral Optometry ----------------------------------------- 47Suraj Upadhyaya

Visual Agnosia: “To See but Not to See” ------------------- 48Safal Khanal

Visual Status for Driving -------------------------------------- 50Sudan Puri

In this IssueTHE SIGHT Vol 6, Issue 6, September, 2010

Nepal Optometry Students’ Society, a group of committed personals always striving for the upliftment and betterment of optometry as a health care profession, got its new body as 9th EXECUTIVE BODY on 26th Bhadra, 2066. After the former body was dissolved a new executive committee was reframed comprising of Mr. Suraj Upadhyaya as President, Ms Sarita Manandhar as Vice-President, Mr. Safal Khanal as Secretary, Mr.Pawan Raj Patel as Treasurer and Mr. Subash Marasini as member and two new members Mr. Mukund Pant and Mr. Khem Narayan Chalise were enrolled to complete the body as per NOSS Bidhan-2057 on 14th Poush 2066. The hand over program was held subsequently with the wishes of successes from the former body.

EVENTS AND ACHIEVEMENTS

Registration: It had been fi ve years since the societys' registration was not renewed at the Chief District Offi ce, Kathmandu. It was fi nally successful with the hard efforts of the body in making the society an authentic registered one.

Governmental post for optometry: The initiative was taken to create a post for optometry at the governmental level and all the processes were carried out submitting all the necessary documents to the Ministry of health, The Apex body of eye health, Nepal Netra Jyoti Sangh and all other concerned bodies.

Laws: Some amendments were made in the laws of the society by calling upon a general meeting on 2nd Ashar 2067 and the further processes were carried out to register the newly formed one on the government level.

World Sight Day 2009: On 22nd Ashoj, 2066 (8th Oct 2009) a grand celebration of the “World Sight Day” with the slogan “Gender and Eye Health; Equal Access to Care” was organized by NOSS 9th EB supported by International Agency for the Prevention of Blindness (IAPB)and Vision 2020:The Right to Sight at BPKLCOS organizing an exhibition, essay competition and eye health education program with the active participation of national reporters.

Annual Optometry Day: A feat of 12 glorious years of optometry was successfully celebrated on the occasion of annual optometry day on 21st Shrawan 2067 organizing a grand program inviting Executive Director, Head of Department,Optometry program co-ordinator,ophthalmology and optometry faculties, Free Students’ Union,all BPKLCOS family and all optometry and ophthalmology residents.

Welcome cum farewell program: On 14th Poush 2066 (29th January 2010), a program was conducted at BPKLCOS premises welcoming 12th batch of optometry as well as bading goodbye to the 8th batch of optometry organizing a formal program inviting Dr. Mohan Raj Bajracharya, Nepal Eye Hospital Director and Prof Ram Prasad Pokhrel NNJS President as special guests as well as an informal musical program.

Little optometrists program: The third phase of little optometrists program was conducted with grand success on 18th Ashar 2067 (2nd July 2010) inviting teachers and students from within and outside the valley and eye health and vision screening awareness seminars (audio visual), group discussion and demonstration.

Annual Optometry Journal-THE SIGHT: The 6th issue of annual optometry journal “The Sight” was published and distributed. The distribution of the 5th issue to graduated optometrists, various eye institutes, medical colleges, opticals and clinics, medical students was successfully accomplished.

Opto sports 2010: A series of sports involving all the optometry students were organized to celebrate 12 glorious years of optometry in Nepal by NOSS 9th EB supported by FSU which included football, cricket, chess, tug-o-war, table tennis and fun games. The prizes and certifi cates were awarded on the annual optometry day to the winners and the co-ordinators.

Opto-quiz 2010: A intra optometry quiz competition was held on 27th Chaitra 2066 (9th April 2010) as a part of opto sports series supported by Free Students’ Union

Dristi wall magazine: The publication of Dristi wall magazine, a monthly publication comprising of articles related to eye health education was continued and every issues were forwarded to graduated optometrists, relevant personalities, eye hospitals of Nepal and abroad via email.

FROM THE SECRETARIAL DESK

nepal optometry students’ society-Safal Khanal

SECRETARY, NOSS

NOSS Bank account: Nepal Optometry Students’ society has open its own Bank account to carry out the fi nancial transactions with ease and transparency

Brock string: The new brock string exercise kit was continuosly made available and distributed maintaining transparency and with equal participation to the patients of binocular vision problems.

International conference: 7 optometry students namely Mr.Suraj Upadhyaya, Mr.Himal Kandel, Mr.Raju Kaiti, Mr. Mahesh Kumar Dev, Mr. Safal Khanal, Mr.Pawan Raj Patel and Mr. Sudan Puri participated and presented posters representing optometry students of Nepal in the international optometry and vision science conference and workshops organized by Elite School of Optometry held at Chennai, India. The opportunities they got by sharing the experiences with foreign professors, students and scrutinizing the global scenario of optometry worldwide is sublime to make a history of goodwill.

Model entrance examination: A model test of optometry was conducted at BPKLCOS seminar hall on 16th Kartik 2066 (31st Oct.2009) to the enthusiastic candidates striving to be a part of IOM optometry family.

Other programs:

a) Participated in World’s AIDS Day organized by Nepal Medical Students’ Society on December 1, 2009 and also held a stall with posters providing awareness on “HIV AIDS in relation to eyes”

b) Actively Participated in No Tobacco Day (31 May 2010), World Kidney Day(10 March 2010) and World Environment Day (5 June 2010)organized by Nepal Medical Students’ Society.

c) Organised an informal interaction program to share good wishes with the program co-ordinator and the faculties on the eve of Dashain and Tihar on 2nd Ashoj 2067.

d) Initiated the process to acquire a room and a computer for NOSS issuing letters to the campus and FSU

e) Updated optometry website with photos, news, forums and educational information.

f) Conducted various school screenings in and outside Kathmandu valley

g) Conducted various health camps in collaboration with NMSS, UNMIN and other organizations

h) Organized an informal program to celebrate Teachers’ Day on 9th Shrawan 2067

i) An optometry seminar was conducted in NAME with interaction session about optometry education on 16th Bhadra 2067.

j) Optometry entrance examination book was updated attaching the correction page and IOM entrance questions.

Lastly we would like to thank all my executive body members for the successful and productive complement of one year tenure helping in the achievement of all our policies and aims. Our events, programs and achievements certainly defi ne our commitment. My vote of thanks also goes to all my optometry faculties and colleagues for their immense support. Last but not the least, special thanks to Free Students’ Union especially Mr. Himal Kandel, The Treasurer, FSU for his outstanding support and co-operation in making all our programs a grand success.

Safal KhanalSecretary

Nepal Optometry Students’ Society 9th Executive Body Second year B.Optometry Student

Maharajgunj Medical CampusMaharajgunj Kathmandu

E-mail: [email protected]@gmail.com

THE SIGHT Vol 6, Issue 6, September, 2010 1


Introduction

In 1992, the World Health Organization (WHO) published a working defi nition of low vision .1 "A person with low vision is one who has impairment of visual functioning even after treatment and/or standard refractive correction, and has a visual acuity of less than 6/18 to light perception, or a visual fi eld of less than 10 degrees from the point of fi xation, but who uses, or is potentially able to use, vision for the planning and/or execution of a task for which vision is essential."

The importance of providing care for children with low vision is accepted by many initiatives, such as VISION 2020, the 2004 Oslo Workshop on Low Vision,2 and the United Nation's global campaign, “Education for All”.

The importance of accurate refraction was illustrated in the study of low vision programs undertaken by the author in Asia.3 It is important to recognize that any improvement in distance visual acuity for a child with low vision can make a big difference to his or her life; it can also improve near vision. This is particularly true for children with hyperopia, aphakia, or nystagmus. When providing low vision care for children, it is therefore vital to consider both distance and near vision.

The use of magnifying devices can be important for a student whose near vision after refraction still remains insuffi cient to read print of the size used in their school books (children should be asked to bring their school books to the low vision clinic).

At least 80% of the world's visually impaired children live in low- and middle-income countries, where less than 10% of them have access to education. This sad fact almost guarantees that these children face a lifetime of poverty and illiteracy.5

Once children with visual impairment have received all the ophthalmic, refractive, and low vision support they need, there are several models for delivering educational

services to them. At present, there is a growing awareness of and movement toward inclusive education throughout the developing world. An inclusive approach to education calls for schools to make appropriate adaptations to the learning environment so that each classroom in a community school is able to address the learning needs of all children, including those with disabilities.5

In Nepal, National Low Vision Program has been lunched with the purpose by the end of fi ve-year with the existing eye care facilities of the country aims to help 11.5 % of total low vision people to come in the main stream of the society. This means the proposed proportion of people such as LV children studying in Braille will start reading print and visually handicapped adult low vision people will be able to perform daily routine household work and other income generating work without support from others. Through the program, optical low vision services have been provided in subsidy or freely for Nepalese low vision clients. We hope this study will refl ect the importance of the program in Nepal.

The study was designed to determine the need for spectacles in students enrolled in Lumbini Zone blind schools, Nepal, to assess the need for optical low vision devices, to determine visual outcome of the use of optical low vision services (both optical low vision devices and distance glasses) and to show the relationship between near visual acuity and reading rate among the visually impaired students who had optical low vision devices.

Methods:

Forty-six students (31 males and 15 females) aged between fi ve and twenty-four years were recruited from eight integrated schools as blind in Lumbini Zone, Nepal between January to December 2008. The primary cause of low vision was diagnosed for each subject by General Ophthalmologist. The ophthalmologist performed anterior segment examination using magnifying loupe and torch, while posterior segment examination was carried out using Heine direct ophthalmoscope with dilated fundus wherever indicated.

Low Vision in Lumbini Zone Blind School Students: Use of Optical Low Vision Services

Hari Thapa, B. Optom, Manoj Sharma, MD, Bimal Poudyal, Rishi Kant Adhikari, MD and Kavita Dhakwa, MD


The distance and near visual acuities, best refractive correction and low vision assessment were performed by the optometrist trained in low vision. Distance visual acuity was recorded with Log MAR chart in external illumination at a distance of three meters. Distance visual acuity was measured separately for each eye and both eye together. Near visual acuity was measured with Light house (letter) near visual acuity chart.

All those with at least light perception vision (PL) in one eye and who had navigational vision were refracted. Those whose distance vision in their better eye improved with refraction were prescribed spectacles. Those unable to read N10 were assessed for LVAs for near. Those with distance visual acuity of < 6/18 in the better eye were assessed for telescopes to aid distance vision. Optical low vision devices were provided free of cost.

The reading rates were measured in those students who had been using optical low vision devices for near since one year (during our study) on a range of print sizes (on their own text books) with optical low vision devices in external illumination (window light).

The numbers of students were selected for reading performance through the following criteria:Appropriate passage of 200 – 300 words in student’s primary reading medium was selected Students to read orally (using own text book, with devices) was asked. The time spent was recorded in reading Minimum 5 comprehension questions were asked: 80 % (4 questions) need to be answered correctly.

If 80 % has been scored, calculate the rate of reading: No. of words in passage = words per minute (WPM)No. of minutes spent in readingSo, for reading performance only 20 students were selected.

Data was collected on Standard Clinical Low Vision Assessment Form, National Low Vision Program and analyzed that accompanied the form.Results:

Table 1: Low vision category

Vision in best eye Presenting

Improved with distance

glasses

Improved with

telescope6/18 - 19<6/18 - 6/60 15 23 10

<6/60 - 3-60 20 18 0<3/60 -0.1/60 11 5 0PL / NPL - - 0

Total 46 46 29

A total number of 46 students were enrolled in 8 integrated schools were examined. The age of the students ranged from 5 to 24 yrs.

Lens related anomalies were the most frequent abnormality leading to visual loss, accounting for 41%.

Visual status of students with distance glasses and optical low vision services:

Among the students, 50% could achieve a distance visual acuity of 6/60 or better after receiving the correct spectacles (Table1). 63% students had improved with distance glasses. However, only 24% students already had spectacles when they presented (Figure1), but in 9% the visual acuity could be improved with a change in prescription and in total 48% needed a new pair.

Table 2: Near Vision Category

Size Presenting Improved

<1-1.5M 10cm or more 13 23

1-1.5M < 10cm 3 19

>1.5-2.5 M 10cm or more 12 1

>1.5-2.5 M <10cm 2 3

>2.5 M 16

PL

Total 46 46Table 2 shows that at presentation, there were 35% students having near vision >2.5 M. After low vision assessment, all the students were near vision 2.5 M or better than 2.5 M. 91% students were able to read 1.5 M at 10 cm or better than 1.5M print size.

In telescope trial, 63% students were improved distance vision with telescope. 41% were distance visual acuity 6/18 or better than 6/18. (Table 1)


Table 3: Types of optical low vision devices

Number(%)

Distance glasses given enough improvement 13For nearSpectacle Magnifi er 63Hand held Magnifi er 7Stand Magnifi er 13Total 83For distanceTelescope,3x 4Telescope,4x 24Total 28Both magnifi er + telescope 26

Table 3 shows that 13% students were able to read 1M print size with distance spectacles. Near Magnifi ers were needed for 83% students. Distance telescopes were benefi ted to 28% students.

94 WPM was recorded in a student with near visual acuity 0.8 M wherever 15 WPM was found in a student with near vision 2M. There was 94 WPM at the age of 11 yrs whereas at the age 15 yrs, reading rate was 36 WPM.

Discussion:

50% of the total students enrolled in the resource centers had distance vision <6/18 to 6/60, despite the admission criteria requesting a medical certifi cate of blindness. Most of the students came from small town near the blind schools. Parents frequently seek admission of their children even though they might not be blind, because schools offer lodging & food, & often better education.

In a study undertaken by the author Van Dijk K, retrospective study of low vision programs in Asia, 2005, in which data from standardized clinical records of 1,823 children, aged from 0 to 15 years, attending six low vision programs in India, Indonesia, and Nepal in 2002 and 2003 in Asia3, where analyzed among the children, more than two-thirds could achieve a distance visual acuity of 6/60 or better after receiving the correct spectacles. For many children, this level of vision is suffi cient to allow them to read a blackboard from the front row in a classroom, these children generally only require minimal additional support.

Need for distance spectacles:

In the study, corrective lenses improved distance visual acuity in the better eye in 63% students, 24% of the

students already had spectacles when they presented, but in 9% the visual acuity could be improved with a change in prescription and in total 48% needed new pairs of glasses.

Similarly, a retrospective study of low vision programs in Asia done by Van Dijk K found that 36% of the children already had spectacles when they presented, and half of those needed a new pair. 3

Need for optical low vision devices:

83% students required optical low vision devices (LVDs) for near.

After low vision assessment, all the students were near vision 2.5M or better than 2M letter size. 91% students could read print size 1.5 M or better than 1.5 M at 10 cm after refraction and/or magnifi cation. Similar fi nding was found in, a retrospective study of low vision programs in Asia done by Van Dijk K found that a total of 75% of the children examined achieved a best corrected near vision of 1.25M (N10) or better, and an additional 18% could read a large print size of 2–2.5M (N16–N20) after refraction and/or magnifi cation. These students thus had suffi cient near vision to read the print used in school books (sometimes with some assistance). None of them needed to learn Braille (although some had already been taught it), and they gained the ability to attend local mainstream schools with their fully sighted peers.3

There is debate whether schools for the blind in developing countries should use enlarging photocopiers to produce educational materials for students with low vision. These machines are expensive to purchase and run, depend on electricity, need regular supplies of paper of good quality and standard size, and continued maintenance particularly in hot, dusty climates.5 The fi ndings of this study suggest that accurate correction of refractive errors and provision of appropriate LVDs for near vision would provide a fl exible, cost effective and sustainable alternative.

Reading performance:

In a study done by Jan E Lovie-Kitchin, Jennifer D Bevan, Bronwyn Hein, Maximum reading rate increased signifi cantly with age and near visual acuity.6 Kalloniatis M, Johnston AW found that there was a signifi cant correlation between reading rate and near VA for children with low vision.7 In our study, it was shown that reading rate increased signifi cantly with increasing near visual acuity but there was no signifi cant relationship between reading rate and age.


Conclusion: In summary,

- The need for spectacles in students with low vision were 63%

- 83% students needed Magnifi ers for near and 28% needed telescopes for board work

- At presentation, there were 35% students having near vision better or equal to 1.5 M at 10 cm whereas 91% students could able to read same print size at 10 cm after refraction and /or magnifi cation.

- In telescope trial, 63% students were improved with telescope

- Maximum reading rate increased signifi cantly with near visual acuity.

Recommendation:

Accurate refraction of students with high refractive errors often in association with media opacities is not easy and requires experience and patience. It is recommended that the students with visual handicap in blind schools be refracted annually and spectacles made available to them at no or minimum cost.

To provide sustainable, low cost, low vision services close cooperation between clinical low vision practioners, trained teachers, community based rehabilitation persons and parents will be essential.

Acknowledgement :

We wish to acknowledge Karin van Dijk, CBM Low Vision Specialist, Low Vision Consultant to Dark & Light Blind Care and to Kilimanjaro Centre for Community

Ophthalmology, The Netherlands for her valuable advice and Dark and Light Blind Care for their support to National Low Vision program in Nepal.

References:

1. WHO. Management of low vision in children : report of a WHO consultation http://whqlibdoc.who.int/hq/1993/WHO_PBL_93.27.pdf(Accessed 1 September 2009)

2. The International Society for Low Vision Research and Rehabilitation. Toward a reduction in the global impact of low vision: report on an October 2004 meeting in Oslo http://www2.nutn.edu.tw/vhc/english/Oslo%20Workshop%20Report.pdf(Accessed 5 September 2009)

3. Van Dijk K. Unpublished retrospective study of low vision programs in Asia, 2005

4. Campbell L, Mani MNG. Providing educational services. Community Eye Health. 2007;20(62): 21-23

5. Silver J, Gilbert CE, Spoerer P. Low vision in east African blind school students: need for optical low vision services. Br J Ophthalmol. 1995;79:814-820

6. Lovie-Kitchin JE, Bevan JD, Hein B. Reading performance in children with low vision. Clin Exp Optom. 2001; 84(3):148–154.

7. Kallonaitis M, Johnston AW. Visual characteristics of low vision children. Optom Vis Sci. 1990; 67(1):38- 48.

Authors CorrespondenceHari Thapa

OptometristLumbini Eye Institute

Bhairahawa RupendehiE-mail: [email protected]


Introduction

Visual impairment is a globally prevalent issue in both adults and young populations. According to World Health Organization (WHO),1 in 2002 there were more than 161 million visually impaired people. Thirty-seven million people were blind and one-hundred twenty four million people had low vision. Low vision interferes with many daily activities. It affects a person’s academic and economic life and even his/her social life. Patients with low vision have many different goals for their low vision rehabilitation. Reading is one of the most common goals reported by adults with low vision.2 Unlike adults with low vision, low vision may cause a lifelong reduction in a child’s visual performance.3 Reading is one of the main avenues for education and educational achievement. If visual impairment affects the child’s ability to read, it could be a great impediment of his/her educational success.4 Reading is a fi rst step in education and is a predictor of good academic success.5 The fi rst barrier to reading for most children with low vision is the print size. Children with low vision usually need some form of magnifi cation to resolve letters that are lower than their threshold.6 During a low vision assessment, reading performance is not assessed expect for a brief assessment of thresholds and fl uency.7 With a detailed low vision examination and an accurate visual correction, children might achieve a better reading performance. There are other examinations than visual acuity that should be included in the low vision examination. Acuity reserve and contrast reserve are good predictors of reading performance in adults and are likely to be important in children. The optimum magnifi cation, acuity reserve and contrast reserve tend to lead to the optimum possible reading fl uency.


Reading in Children with Low Vision Balsam Alabdulkader and Susan J. Leat

In this paper we review the literature that relates to visual reading in children with low vision with an emphasis on visual requirements in terms of acuity (or magnifi cation), contrast and visual fi eld.

Relationship to Visual Acuity

A typical low vision examination always includes a visual acuity test. Visual acuity on its own used to be considered as the only predictor of reading ability.8 Recent studies have shown that this is not the whole story.8,9 Whittaker and Lovie-Kitchin8 defi ned the Acuity Reserve as the ratio of the print size of the reading material to the subject’s visual acuity threshold for a particular print being read. With a 1:1 i.e., or no acuity reserve patients can still read, but very slowly. With the optimum acuity reserve patients can read more easily and have a higher reading rate. Whittaker and Lovie-Kitchin used published data from three previous studies10,11,12 and re-plotted the results to show the effect of acuity reserve on reading speed. Also, they indicated that the majority of low vision professionals tend to work with patients who, at the time of assessment, had an acuity reserve of 3:1 or less. An acuity reserve of 18:1 was the maximum of the optimum acuity reserve range and with higher reserves than this, the reading rate drops. For most adults an acuity reserve between 6:1 and 18:1 is required to achieve maximum reading rate.8Kestenbaum and Sturman13 suggested a rule to calculate the reading addition for a given visual acuity. Kestenbaum’s rule is that the reading addition equals the inverse of the visual acuity. It tends to underestimate the reading addition for a patient 14 and results in the person reading close to the resolution limit. Kestenbaum’s rule is mainly used as a starting point for the required reading addition. Most derivatives from

Abstract

There have been numerous and extensive studies into the visual requirements for reading in adults with low vision. There are far fewer studies involving children with low vision. This article compares the studies on children which do exist with the fi ndings in adults. Acuity reserve (magnifi cation), contrast reserve and visual fi eld requirements are considered. We also review the literature which compares the effi cacy of large print with optical magnifi cation for children. From the few studies that exist, there are indications that the requirements for children are not the same as for adults. Therefore, we suggest that one cannot directly apply the results from adults to children and that there is a gap in the literature (and therefore our understanding) of the visual requirements for reading in children.


Kestenbaum’s rule reported an additional magnifi cation to the original rule of 1.5 to 2.0x.14 Clinically, professionals suggested more magnifi cation or acuity reserve for better reading performance.14 Raasch and Rubin, in a study of patients with age-related macular degeneration, argued that patients need 6x or maybe more than Kestenbaum’s rule to achieve the maximum reading rate. 14

In a study on sighted children by Lueck et al,15 a comparison was made of the required visual acuity reserve for reading text and unrelated words. The results indicated that four times acuity reserve is needed for sighted children to read text materials aloud. Less acuity reserve is required to read unrelated words.

A more recent study of Lueck et al16 showed that children with low vision need at least three times acuity reserve to read effi ciently. This results in much larger print size being required for children with very low visual acuities for them to gain the optimum acuity reserve. Lueck et al16 reviewed some ways that help children with low vision achieve the optimum acuity reserve. These include decreasing the reading distance, increasing the print size material or using a low vision aid.

Lovie-Kitchin et al17 reported a study of adults and children with low vision that showed that the acuity reserve for children should be between 2.5:1 and 8:1 and between 2:1 and 8:1 for adults for maximum reading rates to be achieved. These results are lower than Whittaker and Lovie-Kitchin8 found for adults but there is some overlap.

In another study on children by Lovie-Kitchin et al,4 acuity reserve between 2.5:1 to 7:1 was necessary to achieve maximum reading rate. Patients with lower near visual acuities tend to achieve maximum reading rate with less acuity reserve, which was an unexpected result in this particular study and in contrast to Lueck et al above.16 Interestingly they found that, unlike adults with low vision, age was a better predictor of reading rate than near visual acuity in children with low vision.

A variety of reading tests have been used for these studies.Some studies have used standardised tests of reading and some researchers have developed their own tests of reading based on similar principles. Figure 1 show examples of reading cards that have been used. Lueck et al15,16 used the Bailey-Lovie Word reading cards and sentences from the MNRead test (Figure 2) while Lovie-Kitchin et al 17 used the Bailey-Lovie Word reading cards and charts created from standardised children’s texts.

Figure 1. An example of the Bailey-Lovie Word reading card.

Thus, there are only three studies on how much acuity reserve is needed for children to achieve maximum reading rate. It ranged between 2.5:1 and 8:1. Further studies for children should be done to confi rm these results. Table 1 summarises the results of studies that measured acuity reserves in adults or children.

Relationship to type of magnifi cation

The fi rst common impediment of reading for low vision patients is the text print size. Different methods can be used to magnify text and give better reading performance. In the literature on this subject, eye care professionals and educators have debated whether it is more benefi cial to use a magnifi er or large print text to obtain magnifi cation. According to McCurry et al,18 most children with low vision tend to benefi t from using magnifi ers to read standard print. In this study, all of the children underwent a regular low vision assessment of their visual performance. This included a reading performance evaluation using a magnifi er. The study’s aim was to determine the effectiveness of using magnifi ers to read standard print size. The results showed that near vision performance was improved for 28% of the children’s with spectacles and/or magnifi ers and that 54.3% of the children were enabled to read standard print size. Also, nearly half of the children showed improvement in their reading and/or writing skills with spectacles and/or magnifi ers. In addition, the study reported that most magnifi ers used were stand magnifi ers. This study is in agreement with Leat and Karadsheh’s19 study, in which they reported that stand magnifi ers tend to be the fi rst choice of near low vision aids by children.

Farmer and Morse’s study20 made a comparison between two groups of children. The fi rst group of children used large-print text for reading while the second group used magnifi ers. The results showed that the fi rst group had an increase in reading speed rates but with no signifi cant


Table 1. Studies of Acuity Reserve

Study Type of study Subjects Results

Lovie-Kitchin et al4 Reading performance and vision measures compared

Participants with low vision aged 7-18 years

Acuity reserve between 2.5:1 and 7:1 is required for children and teenagers

Whittaker and Lovie-Kitchin8

Collected data from three previous studies10,11,12

Adult with normal and low vision10, 11,12

Acuity reserve between 6:1 and 18:1 is required for optimum reading

Lueck et al15 Reading rates measured for print of different sizes and distances

11 4th graders with normal vision

Acuity reserve of ≥ 2.5 required.

Lueck et al16 Reported values from Lueck et al15

Reading rates measured for different print sizes and distances

11 sighted 4th graders

6 children with low vision

Acuity reserve between 1.25x and 4x required.

Acuity reserve of ≥ 3x required

Lovie-Kitchin et al17

Print sizes that give maximum reading rates for adults and children

Adults aged 20-73 years and children aged either 7 or 8 years with normal vision

Acuity reserve between 2:1 and 8:1 required for adults Acuity reserve 2.5:1 and 8:1 required for children

increase in reading comprehension skills. On the other hand, the second group of children showed an increase in their reading speed rates and a noticeable increase in their reading comprehension skills.

In a study by Kalloniatis and Johnston,7 children’s clinic fi les were reviewed to fi nd relevant data. Then the children’s reading performance was assessed in their regular classroom with the use of their low vision aids. In general, the children had a high rate of low vision aids usage. More specifi cally, it was also found that the children’s vision could be improved by using simple low vision aids. The study concluded that the children preferred to move their reading material closer (use a close reading distance) than to use a low-powered near low vision aid.

In the study by Silver et al,21 which included 230 children at a school for the blind, visual acuity was used to determine the need for magnifi cation or glasses. The majority of these children (57%) were only taught Braille and treated as totally blind, although 79% of these children could benefi t from near low vision devices or reading spectacles and be enabled to read normal print. This study raises the importance of magnifi cation, and the effect on the children’s academic life. This study also reported that stand magnifi ers seem to be the easiest optical magnifi ers for children to use.

Thus there is only one study that directly compares optical magnifi cation with large print and this showed that using

magnifi ers was more effective compared to providing large print text. Many studies, however, have described the benefi ts of optical magnifi cation 21,20,18,3 to help children with visual impairment to read. Using magnifi ers does not limit the childrens’ reading material to that which is enlarged only and allows children to access any written information in normal print size. Producing large print books is expensive. However, enlarging photocopying is more available nowadays and also changing the font size on a computer document is easy. Magnifi ers are also the only option for children who require higher levels of magnifi cation for whom providing large print materials is impossible, although a combination of large print and optical magnifi cation is also an option. Thus it seems that, for better education achievement, children with low vision should be assessed for magnifi ers and be taught and trained how to use them effectively.

Relationship to Contrast Reserve

According to Whittaker and Lovie-Kitchin,8 the ratio of the letter contrast to the subject’s contrast threshold for a reading print is defi ned as the Contrast Reverse. Decreased print contrast and also decreased contrast sensitivity of the observer results in a reduction of the contrast reserve. In this study of adults with low vision, Whittaker and Lovie-Kitchin used published data from three different experiments.9,22,23 Results were re-plotted together and


it was found that decreasing contrast reserve resulted in declined reading rate. People with normal sight also experience low reading rates if the contrast reserve is less than 20:18. Whittaker and Lovie-Kitchin8 suggested that the optimum contrast reserve for maximum reading rate is higher than 30:1 and for high fl uent reading a reserve of 10:1 is required. Also, it was found that for 6 degree letters the majority of patients with low vision have a 0.10 or higher contrast threshold.9 Thus patients with low vision have reduced reading rate because, even with video magnifi ers that give a contrast of almost 1 (100%) and plenty of magnifi cation, their contrast reserve may be less than 10:1.8

In a study of young normally sighted adults, Mohammed and Dickinson,24 studied the effect of contrast reserve on reading performance. This was evaluated by comparing different magnifi cation powers with controlled fi eld of view. It was found that providing the patient with higher magnifi cation could not compensate for a low contrast reserve and thus lead to a more optimum reading rate. It was found that reading performance declined whatever the level of magnifi cation if the contrast reserve was lower than 10.5:1, which is in agreement with the study by Whittaker and Lovie-Kitchin.8

According to Leat and Woodhouse,25 contrast sensitivity was a predictor of reading speed. The study included 30 adult subjects. The authors concluded that contrast sensitivity at 0.5c/deg was correlated with reading performance and contrast sensitivity at high spatial frequencies was a poorer predictor of reading speed compared to contrast sensitivity at the lower spatial frequencies. The study suggested that contrast sensitivity should be included in a regular low vision assessment.

A recent study by Lovie-Kitchin et al,4 the only study of contrast sensitivity and reading in children, found quite different results than those reported in adults with low vision.8,24,25 In this study, the contrast sensitivity for 71 students (aged 7-18 years) was measured at low to mid spatial frequencies. However, it must be noted that the children generally had relatively good contrast sensitivity.

Only four children had contrast sensitivity less than 10. It was concluded that, unlike adults with low vision, contrast sensitivity was not a good predictor of reading rate in children with low vision and it would not be helpful to include a contrast sensitivity measurement routinely in a clinical low vision assessment for reading in this population.

Relationship to Visual Field

In the study by Whittaker and Lovie-Kitchin,8 the results of two studies26,12 of adult subjects with normal and low vision were re-plotted. It was found that, for both normal and low vision subjects, reading rate increased as fi eld of view increased. Subjects with low vision use low vision devices and usually need to move the reading material as close as possible to the eye.8 The authors suggested that the fi eld of view restricted by simple low vision devices is not signifi cant. It was also concluded that, if people with low vision are taught to manipulate the low vision device and place the text within the fi eld of view of the device, a large fi eld of view is not necessary for fast reading rate.

In a study by Legge et al,27 141 adults with low vision were included. The study’s aim was to determine which clinical measurement was a good predictor of reading speed. Field of view was examined by Goldmann perimeter or tangent screen. If the subject had a scotoma that covered all or part of the central 5° of the visual fi eld he/she was classifi ed as having central loss. If not, he/she was classifi ed as having central fi eld intact. It was found that central visual fi eld loss was associated with slow reading speed. It was, however, not a predictor of slow reading speed. On the other hand, it was found that the majority (74%) of slow readers had central loss.

According to Gompel et al,28 visual fi eld defects do not affect children’s reading speed and comprehension. This study compared two groups of children with low vision. The fi rst group included children with low vision who had visual fi eld restrictions and the second group were children with low vision and intact visual fi elds. Interestingly, no differences in reading speed and reading-comprehension skills were found between these two groups of children with low vision. This is the only study on the effect of

Study Brief description Subjects ResultsWhittaker and Lovie-Kitchin8

Collected data from three previous studies9,22,23

Adults with normal and low vision 9,22,23

Contrast reserve of >30:1 required

Mohammed and Dickinson24

Effect of low contrast reserve on reading performance with different magnifi cations

Young university students with stimulated low vision

Contrast reserve of >10.5:1 required

Table 2. summarizes the results of studies that measured contrast reserves in adults or children.


visual fi eld constrictions on reading speed rate in children with low vision. More studies need to investigate the importance of fi eld of view on reading speed in children with low vision.

Conclusion

Adults with low vision can read effectively when the main criteria for good reading are met. These include magnifi cation, acuity reserve, contrast reserve and visual fi eld. Little is known about the similar requirements for children. It does appear that acuity reserve should be at least 2.5:1.17,4 This can be achieved by increasing the magnifi cation which may possibly help to compensate for any low contrast reserve. There have been no studies that have investigated the minimum contrast reserve required for children with low vision to read easily, although one study showed that contrast sensitivity may be less of a limitation in young people than older adults. In adults, a contrast reserve of more than 10:18,24 is needed to achieve the optimum reading speed rate. Using electronic magnifi ers or high contrast print could help to compensate for low contrast sensitivity for the children with low vision and good illumination may improve contrast sensitivity in some cases. Children with clear media and intact central visual fi eld should be able to read reasonably well. Adequate magnifi cation resulting in a good acuity reserve and contrast reserve would be expected to lead to better reading performance.

Thus there are indications that children do not perform in exactly the same way as adults4 and the adult data may not be directly applicable to children. Further studies for children should be done to further investigate the parameters that may affect the childrens’ reading performance so as to further our knowledge and improve the clinical assessment of reading and provision of reading aids in children.

References

1. World Health Organization. Magnitude and Causes of Visual Impairment. Available at http://www.who.int/mediacentre/factsheets/fs282/en/index.html. Accessed May, 2009.

2. Elliott D, Trukolo-Ilic M, Strong J, Pace R, Plotkin A, Bevers P. Demographic characteristics of the vision-disabled elderly. Invest Ophthalmol Vis Sci. 1997;38:2566-2575.

3. Bevan J, Lovie-Kitchin J, Hein B, et al. The effect of relative size magnifi cation vs. relative distance magnifi cation on the

reading performance of children with low vision. In: Stuen C, Arditi A, Horowitz A, Lang M, Rosenthal B, Seidman K, editors. Vision Rehabilitation Assessment, Intervention and Outcomes. New York: Swets & Zeitlinger, 2000:428-432.

4. Lovie-Kitchin JE, Bevan JD, Hein B. Reading performance in children with low vision. Clin Exp Optom. 2001;84:148-154.

5. Stelmack JA, Tang XC, Reda DJ, Rinne S, Mancil RM, Massof RW. Outcomes of the Veterans Affairs Low Vision Intervention Trial (LOVIT). Arch Ophthalmol. 2008;126:608-617.

6. Wolffsohn JS, Eperjesi F. Predicting prescribed magnifi cation. Ophthalmic Physiol Opt. 2004;24:334-338.

7. Kalloniatis M, Johnston AW. Visual characteristics of low vision children. Optom Vis Sci. 1990;67:38-48.

8. Whittaker SG, Lovie-Kitchin J. Visual Requirements for Reading. Optom Vis Sci. 1993;70:54-65.

9. Rubin GS, Legge GE. Psychophysics of reading. VI--The role of contrast in low vision. Vision Res. 1989;29:79-91.

10. Legge GE, Pelli DG, Rubin GS, Schleske MM. Psychophysics of reading-I. Normal vision. Vision Res. 1985;25:239-252.

11. Legge GE, Rubin GS, Pelli G, Schleske MM. Psychophysics of reading-II. Low vision. Vision Res. 1985;25:253-266.

12. Lovie-Kitchin JE, Woo GC. Effect of magnifi cation and fi eld of view on reading speed using a CCTV. Ophthalmic Physiol Opt. 1988;8:139-145.

13. Kestenbaum A, Sturman RM. Reading glasses for patients with very poor vision. Arch Ophthalmol. 1956;56:451-470.

14. Raasch TW, Rubin GS. Reading with low vision. J Am Optom Assoc. 1993;64:15-18.

15. Lueck AH, Bailey IL, Greer R, Dornbusch H. Magnifi cation needs of students with low vision. In: Stuen C, Arditi A, Horowitz Lang MA, Rosenthal B, Seidman K, editors. Vision rehabilitation in the 21st century. Downington, PA: Swets & Zeitlinger; 2000:311-313.

16. Lueck AH, Bailey IL, Greer RB, Tuan KM, Bailey VM, Dornbusch HG. Exploring print-size requirements and reading for students with low vision. J Vis Impair Blind. 2003;97:335-354.


17. Lovie-Kitchin JE, Oliver NJ, Bruce A, Leighton MS, Leighton WK. The effect of print size on reading rate for adults and children. Clin Exp Optom. 1994;77:2-7.

18. McCurry L, Gilbert C, Silver J, Ackep E, Afenyo G. Identifying children who may benefi t from magnifi ers: Visual assessment of children with low vision in South America and West Africa. Int Congr Ser. 2005;1282:413-417.

19. Leat SJ, Karadsheh S. Use and non-use of low vision aids by visually impaired children. Ophthalmic Physiol Opt. 1991;11:10-15.

20. Farmer J, Morse SE. Project magnify: Increasing reading skills in students with low vision. J Vis Impair Blind. 2007;101:763-768.

21. Silver J, Gilbert C, Spoerer P, Foster A. Low vision in east African blind school students: need for optical low vision services. Br J Ophthalmol. 1995;79:814-820.

22. Legge GE, Rubin GS, Luebker A. Psychophysics of reading-V. The role of contrast in normal vision. Vision Res. 1987;27:1165-1177.

23. Brown B. Reading performance in low vision patients: Relation to contrast and contrast sensitivity. Am J Optom Physiol Opt. 1981;58:218-226.

24. Mohammed Z, Dickinson CM. The inter-relationship between magnifi cation, fi eld of view and contrast reserve: the effect on reading performance. Ophthalmic Physiol Opt. 2000;20:464-472.

25. Leat SJ, Woodhouse JM. Reading performance with low vision aids: relationship with contrast sensitivity. Ophthalmic Physiol Opt. 1993;13:9-16.

26. Legge GE, Rubin GS, Pelli DG, Schleske MM. Psychophysics of reading. II. Low vision. Vision Res. 1985;25:253-265.

27. Legge G, Ross J, Isenberg L, LaMay J. Psychophysics of reading. Clinical predictors of low-vision reading speed. Invest Ophthalmol Vis Sci. 1992;33:677-687.

28. Gompel M, Van Bon WHJ, Schreuder R. Reading by Children with Low Vision. J Vis Impair Blind. 2004;98:77-89.

Authors CorrespondenceSchool of Optometry, University of Waterloo,

200 University Ave West, Waterloo, Ontario, N2L 3G1Canada



Wearing Aid as a Remedy to Headache Rabindra Adhikary, B. Optom

Introduction

With the increasing urbanization, workload and mental stress, the population complaining of headache has been alarmingly rising throughout the past few decades. Any of the liable systemic conditions excluded, patients remain hovering round for quite long in vain before, and hopefully fi nally, they come to eye practitioner. It is reasonable but necessary for any personnel to have his/her eye checked before going to expensive and sophisticated neurological tests on way to rule out the cause of headache. This, however, does not mean that a subject with the signs suggestive of papilledema need not go for an MRI or a CT scan, but for glasses. Meanwhile, reasons always exist behind.

Headache is an important cause of health complaints and disability worldwide. Headache can impair the job productivity and reduce quality of life. Due to lost workdays headache has serious socio-economic impact. Many affected people are reluctant to seek medical treatment. Most people with the tension type of headache

manage themselves.

The proportion of refractive errors in the general population ranges from 13-80% in various studies. In different geographic areas and age groups prevalence rate varies considerably. Although not based on fi rm evidence, uncorrected refractive error (especially hyperopia) is considered to be a possible cause of headache. The criteria for classifi cation of headache of the International Headache Society (IHS) include an entity "Headache Associated with Refractive Error (HARE)" but it is indicated that its importance is widely overemphasized. Moreover, in most optometric studies, the degree of ametropia is defi ned rather arbitrarily. For optical reasons low degrees of ametropia were included since especially these might be of importance in relation to headache.

Materials and Methods

This was a prospective interventional study conducted over 20 weeks (Feb 2009 to July 2010) at Reiyukai Eiko Eye Hospital, Banepa. To exclude the practitioner's and

Abstract

Purpose: Refractive error is considered to be a possible cause of headache in pre-presbyopes. We aim to gain insight into the relation between habitual refractive error (sphere and astigmatism) and headache complaints.

Methods: In a prospective interventional study the refractive state of 116 subjects, attending the regular OPD of Reiyukai Eiko Masunaga Eye Hospital (REMEH), Banepa, aged between 10-34 years was measured using an auto-kerato-refractometer ( Topcon KR-3000). Headache complaints were measured using a questionnaire before and after intervention of apposite refractive correction. Data were analyzed using MS Excel 2007.

Results: Among 116 Nepalese sample, 20.7% were male and 79.3% were female. Most of the patients presented with temporal and frontal headache. The age group of 15-19 prevailed in our study. Crowd/noise and miscellaneous were the major precipitating factors to aggravate the headache severity. After correction with glasses, moderate headache was substantially reduced.

Conclusions: Of the cases of headache, there lies low magnitude of refractive errors, and after optical correction most of the symptoms related to headache resolve.

Key Words: Headache, refractive error, hyperopia


subjective bias, the fi nal prescription constituted the average outcome of at least 3 readings each eye from automated kerato-refractometer (Topcon KR-3000) later verifi ed by subjective refraction, non-accepting subjects being excluded from the study. All the examinations were carried out by the same observer (The author), who did not know the results of the headache questionnaire of each subject. Right eyes were always measured before the left eyes.

Inclusion Criteria

• Pre-presbyopic (<35yrs) subject complaining of headache with no any apparent systemic association responsible for the same and binocular vision disorders.

• All the patients recruited in this study had visual acuity not less than 6/6 partial (Among 6, 3 letters should have been correctly recognized) in the worse eye.

Exclusion Criteria

• Systemic conditions viz hypertension, sinusitis etc.

• Refractive power beyond the range of ± 0.50 Ds

Sampling

We undertook 3 consecutive pilot surveys each lasting 10 days as to the percentage of male and female attending our OPD with headache complaints, this reduced the gender bias on selection of our sample. The average of 3 surveys was male 21% and female 79%. The sampling obviously has to be purposive as its only after four female that a male was taken.

Questionnaire

The questionnaire included simple 5 adopted questions, region of headache, whether associated to eyeball pain

or not, precipitating factors and comparative judgment of severity of headache before and after intervention. Headache characteristics were assessed using the adapted version of Waters' Headache Questionnaire (WHQ), in partial manner.

Results

Of 116, 24 (20.7%) were male and 92 (79.3%) were female. Maximum were from late teen age.

Region of Headache

Region No PercentageFrontal 22 19Parietal 9 7.7Occipital 10 8.6Temporal One sided 8 6.9

Two-sided 15 13Peri-Ocular 7 6Mixed (More than one region) 21 18.1

Non-specifi c 7 6Overall 17 14.7Total 116 100

Eye Ball Pain

Response No PercentageYes 43 37No 59 51Not Confi rmed 14 12

Fig. 1. Age range of subjects and Percentage

Fig. 2. Number of Subjects and the Severity Characteristics before and after intervention


Precipitating Factors of Headache

Factors No PercentageSunlight 16 13.8Crowd/Noise 29 25Closed Space 7 6Near work 22 19Others (cold, loneliness etc)

42 36.2

Discussion

In most of the available literatures, it has been stated that female population are more prone to the complaints of headache. The underlying reason might be the family tension borne by the female in contrast to male counterpart, and at least in this part of world this may hold true, it raises a suspicion as to the cause when most of the papers from the west also refl ects the same. Gist the reasons are galore.

The line chart here shows that the extent of headache has decreased in most of the population group except the very severe one. Some of the subjects in the severe group later complained of headache increasing on wearing glasses.

The population group of 15-19 years seemed to prevailed in our study. This obviously is not irrational as the late teen agers tolerate metamorphosis of emotional havoc and upheaval. Plus their most of the time may be whiled away doing fi ne/ academic works owing to stress/ fatigue related headache. Probably some of the teen-agers also seek attention and some other adopt as an imitation to their bespectacled peers.

Limitations

There have been many reported cases of resolved headache after wearing low power lenses. Paying no disagreement, as those induced by asthenopia frequently abate after optical correction, we wanted further exploration if plane power

lenses have got similar effects. There would have been an unambiguous idea if we could have done the comparative study between the groups with low power prescription and plano power prescription. Defi nitely, placebo effect has something to do with the headache. More, we couldn't effectively appraise for the systemic conditions that might still remain besides our enquiries, a rather effi cacious tools could have been employed . Unlike other studies, we didn't assess headache according to duration and burden but only region and intensity.

References

1. Rasmussen BK. Epidemiology of headache. CEPHALGIA. 2001; 21:774-7

2. Meuller L. Tension type, the forgotten headache. Postgrad Med 2002; 111: 25-38.

3. Aine E. Refractive errors in Finnish rural population (Copen). 1984; 62: 944-54.

4. Waters WE. Headache and the eye. A community study. Lancet. 1970; 2: 1-4.

5. Headache classifi cation committee of the international headache society. Classifi cation and diagnostic criteria for headace disorders, cranial neuralgia and facial pain. Cephalgia. 1988; 8 (suppl 7): 1-96.

6. Gordon DM. Some headaches in an ophthalmologist's offi ce. Headache. 1966; 6: 141-6.

7. Waters WE. Community studies of the prevalence of headache. Headache. 1970; 9: 178-86.

Author Correspondance Rabindra Adhikary

OptometristReiyukai Eiko Masunaga Eye Hospital

Benepa KavreE-mail: [email protected]



Profi le of Pediatric Low Vision at Sagarmatha Chaudhary Eye Hospital, LahanMahesh Kumar Dev, Final year, B.Optometry

Introduction

A blind child is an individual of age less than 16 years who has visual acuity of <3/60 in the better eye. Visual impairment occurs when any part of optical system is defective, diseased or malfunctions. The pediatric population is susceptible to visual impairment as a consequence of congenital, hereditary, infectious, infl ammatory & neoplastic disorders. The major causes of vision impairment in children include refractive error, corneal scarring, congenital cataract, congenital glaucoma, retinopathy of prematurity (ROP). Other causes are albinism, optic atrophy, microphthalmos,aniridia and some rare etiologies like Leber’s congenital amourosis (LCA), cone- rod dystrophy, colobomas, retinal detachment (RD), trauma, diabetic retinopathy (DR).

Visual impairment in children is more common in developing countries due to inadequate eye care professionals to manage treatable causes of blindness like refractive error, cataract and glaucoma. About 40% of the causes of childhood blindness are preventable or treatable. WHO estimates 1.4 million children are blind throughout the world, 1 million of whom live in Asia. Every minute a child in the world goes blind. (WHO2006).

Although the prevalence of visual impairment is relatively lower in children than in adult, the number of ‘blind years’ (number blind × length of life) in children is much greater than blindness occurring in adults. They have a lifetime of blindness ahead.

Methodology

It was descriptive, prospective and hospital based study. All children presenting in LVC of SCEH were included in the study .The study period was of 1 month.

Complete low vision assessment was done which included history taking, functional vision assessment, trial of optical and non-optical devices, prescription of low vision devices, training of low vision devices and counselling.

Results

Out of total 52 patients attending at Low Vision clinic in a month, 24 were pediatric population which accounts for 46.15%. Age of presentation was from 5 years to 16 years. Mean age of presentation was 11.04(SD 3.470). Mean presenting distance VA was 6/70. Mean best corrected VA was 6/43. Mean telescopic vision was 6/14. Mean near VA was 1.43 M. Mean best near VA was 1.02 M.

Abstract

Aim: To determine the prevalence, evaluate the major causes and assess the presenting visual acuity (VA) of pediatric low vision patients attending in Low Vision Clinic (LVC) of Sagarmatha Chaudhary Eye Hospital (SCEH), Lahan.

Method: It was descriptive and prospective hospital based study, assessing Low Vision of pediatric patients of less than 16 years of age presenting in LVC of SCEH.

Result: Out of total 52 patients attending at LVC in a month, 24(46.15%) were pediatric population. Mean age of presentation was 11.04 (SD 3.470). Mean presenting distance VA was 6/70(SD0.063). Major cause of blindness and visual impairment was refractive amblyopia (29.20%). Most of the children (37.5%) had complaint of reading blackboard followed by diffi culty in identifying people (12.5%).

Conclusion: Among the low vision population, number of children is signifi cant and proper low vision intervention is desired.


Most of the children (37.5%) had complaint of reading blackboard followed by 12.5% having diffi culty in identifying people. Major cause of blindness and visual impairment was refractive amblyopia (29.20%), retinitis pigmentosa (RP) & macular cause (12.6%), optic atrophy & neuropathy (8.4%), cortical blindness & disc coloboma (8.4%).

16.7 % preferred using telescope as distance optical device. In 20.8% near VA was achieved by approach magnifi cation.12.5% preferred using spectacle magnifi er as near optical device.

Conclusion

Because of the wide range of causes of childhood blindness, intervention must be disease-specifi c and directed at more than one level of the eye-care delivery system. The current and future directions in research for diagnosing and treating pediatric vision disorders emphasize several areas. They include refractive screening & refractive correction at appropriate time to prevent amblyopia, intraocular lens (IOL) implant, RP intervention and management including genetic counseling etc.

Visual impairment in childhood impacts on the child’s development, education and care given by families & professionals. These infl uence profoundly child’s employment in the future, social prospects and opportunities throughout the life. Impaired vision can affect a child’s emotional, neurological & physical development by potentially limiting the range of experiences & the aids of information a child is exposed to. There is need to assess and provide appropriate low vision rehabilitation services to them.

Limitation

It was short duration study and the small sample size was small.

References

1. M.A.Bamashmus and S.A. Al Akily. Profi le of childhood blindness and low vision in Yemen: a hospital-based study. Eastern Mediterranean Health Journal EMHJ • Vol. 16 No. 4 • 2010.

2. I Kansakar, HB Thapa, KC Salma and et al.Causes of vision impairment and assessment of need for low vision services for students of blind schools in Nepal.Kathmandu University Medical Journal, Vol. 7, No 1 (2009)

3. Clare E. Gilbert, Leon B. Ellwein.Prevalence and Causes of Functional Low Vision in School-Age Children: Results from Standardized Population Surveys in Asia, Africa, and Latin America. Investigative Ophthalmology and Visual Science.2008; 49:877-881.)

4. Goh PP, Abqariyah Y, Pokharel GP, Ellwein LB. Refractive error and visual impairment in school-age children in Gombak District, Malaysia. Ophthalmology 2005; 112:678–685

5. Gilbert C E, Foster A. Childhood blindness in the context of Vision 2020: The Right to Sight. Bull WHO 2001; 79:227-232

6. Silverstone Barabara,Lang A. Mary, Rosenthal P.Bruce,Faye E.Eleonar.The Lighthouse Handbook on Vision Impairment and Vision Rehabilitation, Volume -1.Vision Rehabilitation Oxford University Press; 2000.

Author Correspondance Mahesh Kumar Dev

Final Year B. Optometry StudentMaharajgunj Medical Campus

Maharajgunj KathmanduE-mail: [email protected]



Agreement of Synaptophore and Prism Cover Test Measurements in Strabismus Raju Kaiti , Final year, B. Optometry

Introduction

Synaptophore is primarily an instrument for the investigation of binocular visual functions. It can also measure strabismic deviations. The accuracy of the device is affected by the artifi cial viewing conditions it provides and the patient’s awareness of its close proximity, which results in an increase in the angle in esotropia and a decrease in exotropia. Prisms are widely used as to measure deviation in open space.

Objective

To fi nd out the agreement of prism cover test and synaptophore in squint measurement. Research Hypothesis (Null hypothesis), There is no difference between deviation measured by prism and synaptophore.

Methodology

This is a cross-sectional study, with inclusion criteria of all cases of strabismus presenting to the hospital and exclusion criteria patient with Poor cooperation and no central fi xation. Angle of strabismus was measured with prism cover test by an optometrist. To eliminate biasness, measurement of strabismus in Synaptophore was carried out by another optometrist. Difference of >1 PD was taken as signifi cant. Difference in two methods was calculated for each type of deviation and level of signifi cance was checked with paired t test. Data were analyzed using SPSS-14.

Results:

Total number of cases were 19 among which male 13 (68.4%) and female 6 (31.6%) Mean Age 23.16 ±20.08 Years (7-65 Years) Exotropia was found in 12 (63.2%) and Esotropia in 7 (36.8%). Deviation measured with prism cover test was 22.71±11.78 degree and that with synaptophore was 22.25±12.23 degree. Difference of the mean was 0.47±4.48 (p=0.53, paired t test). Seven (37%) cases showed less deviation with synaptophore, fi ve (26%) cases showed more deviation with synaptophore.The mean of less deviation showed by synaptophore was 4.4 deg (2.5-8 deg). The mean of over deviation showed

by synaptophore was 4.2 deg (1.5-10 deg). In exotropia, synaptophore showed lesser deviation in exotropia but in esotropia synaptophore showed more deviation than prism cover test.

Conclusion:

In overall patients, there was no signifi cant difference in deviation measured by two methods but Synaptophore showed less deviation in exotropia and more in esotropia. Accuracy of Synaptophore was affected by the artifi cial viewing condition in contrast prism measures deviation in open space.

References

1. I Bernadini D. Le Synoptometre. Contribution au problkme des mesures de I’angle objectif. J Fr Orthopt 1975: 7: 10 I- i 23.

2. Bredemeyer HG, Bullock K. Oi-thoptics. Theorq- and Practice. St Louis: Mosby, I 968: I 34.

3. Strabismus- 1995, Vol. 3, No. 2, PP. 71-77 Eolus Press Buren (The Netherlands) 1995 Accepted 18 April 1995

Author Correspondance Raju Kaiti





Postgraduate Degree in Optometry: Explore the OpportunitiesPrakash Paudel, BSc., BOptom, FIACLE, FLVC

Introduction and objective

Every year Nepalese optometrists are being awarded with postgraduate degree from world renowned universities. Most of these degrees are granted for graduate research degrees. This year only, two Nepalese optometry graduates were honored with PhD degree in UK. This may continue in subsequent years as there are more optometrists who have enrolled in Masters and PhD degrees and are aiming to get these awards very soon. Even though optometry education and profession were not in a strong position to compete with students from developed world, Nepalese optometrists’ successfully got enrolment in postgraduate degrees in several famous universities abroad. These were possible for former optometry graduates only because of individual effort they made to receive scholarship and their strong determination to get enrolment. Nepalese health institutions and government always lacked policy on providing higher education or fi nancial assistance to support such students. Amid this circumstance, Nepalese optometrists have fl ourished in foreign countries by being awarded with postgraduate degrees and acquiring research position in optometry schools and universities.

These degrees subsequently will add into a positive contribution in the development of optometry education and profession in the country. But for the time being, to gain more experiences and expertise in the area, the graduates are attracted to the research/academic position in developed countries. They eventually are believed to contribute in an expansion of optometry education and profession in Nepal. As country requires such highly qualifi ed professionals, current optometry graduates should seek and explore the opportunities to enroll in postgraduate degrees. The four-year optometry curriculum in Nepal opens every chance to get into any universities or in professional practice anywhere in the world. To get into the postgraduate research degree, those interested should look for the opportunity and prepare with a vision and commitment.

As the country yet has no postgraduate course in optometry, optometrists should keep searching their possibilities to enroll in such course and ultimately contribute in the development of the profession in Nepal. This paper aims to educate and guide current bachelor of optometry students or practicing optometrists who are interested in obtaining postgraduate degrees abroad.

About postgraduate degrees

Postgraduate education involves learning and studying for degrees or other qualifi cations for which Bachelor's degree generally is required, and is normally considered to be part of tertiary or higher education. These are also known as graduate research degree and are managed by graduate research school of the universities.

A graduate research degree provides a unique opportunity to follow students’ interest in an area of research and make an important contribution to the development of chosen research area. The focus is on the capacity for innovative, independent research, critical thinking, time and project management and problem-solving. Students’ will also need to have, or to develop, excellent skills of organisation and communication.

Those interested should fulfi ll the given eligibility criteria to get a successful enrolment into the graduate research degree. In most countries, the hierarchy of post-graduate degrees is as follow:

Master's in Optometry (MSc)

The Master’s degrees are either by course work or by research. Optometrists who are interested in academic position may pursue optometry education in master’s degree by coursework or clinical science (MOptom) and this usually takes two year to complete. In most universities, international scholarships are not provided for these courses. This degree is available in optometry colleges in India as well. MPhil in optometry is also available in some universities which take one and a half year to complete.


Optometrist who aims for research position may apply for masters by research or PhD. All universities in Europe and America require enrolment in master’s degree before PhD. In some occasion, students are also enrolled in PhD with one year conditional master degree. Student with satisfactory academic progress will continue in PhD. However, in some universities, for example in Manchester University, UK, one must complete one year master degree to get enrolled in PhD programme. In Australia, students may get entry directly into PhD after completing a bachelor degree.

Short-term research projects, such as those undertaken in Honours or Postgraduate Diplomas, are also available in some universities. These are often essential training for graduate researchers. For example, postgraduate diploma is available in UNSW, Australia. However, just as the transition from an undergraduate course, honours or a postgraduate diploma usually requires a student to acquire and develop new skills, which leads to graduate research degree and involves a much higher level of independent thinking, planning and activity.

Doctorate in Optometry (PhD)

These are often offered directly after bachelor’s degree in optometry. Doctorates degree involves a research which should contribute for a novel fi nding or development of innovative technology in the area of work. Scholarships are usually offered in most universities. The PhD can be studied as a part time or full time. In most universities, students usually are required to submit PhD thesis within four years if enrolled as a full time student and seven years if enrolled as a part time. However, for international students, a full time enrolment is required for PhDs.

About Scholarships

Studying in postgraduate course is very expensive for international students. In Australia, it costs AUD$28,000 per annum for tuition fees and another AUD$20,000 for living expenses. Therefore, students from developing world have hardly any options than looking for a scholarship which is very competitive to obtain. In almost every university, various scholarships are available for international students. Optometrists should refer to the website of the universities to know particular scholarships available for the programme. Optometrists also should check institution website since some scholarships are provided by the research institution. For example, in University of New South Wales, apart from university scholarship given to school of optometry and vision science students, Brien Holden vision Institute and Vision

CRC also offer scholarship for postgraduate research degree. Optometrists should check these institutes’ website and enquire about the research areas and scholarships available. To apply in UNSW, visit university website and fi nd different types of scholarships available in every academic year: www.grs.unsw.edu.au/scholarships

In some universities, such as in Canada, for university scholarships students are eligible once they get admission in the course, this means separate application is not required and the successful candidates are later announced by the university. Some scholarships are asxlso offered by government organizations, for example, AusAID, Australian Leadership Scholarship etc. There are many other scholarships available, complete information of which can be obtained in website of these organizations. Information on scholarship is often available through British Council Library, American Library and other embassies in Kathmandu. Students must visit once to these libraries or in the website and fi nd what scholarships and when these are available to apply. For information, AUSAID and relevant scholarships deadline is in July. Similarly, scholarships application deadline at UNSW is 31st August for enrolment in next year’s fi rst session.

Important steps in preparation

Website: Search in the website of the university and also try to fi nd graduate research school or optometry department link or website for detail information For UNSW, go to www.grs.unsw.edu.au and also www.optom.unsw.edu.au Students must know the academic requirements, scholarship application date and dates of admission even before applying in the programme. To apply in Australia, search the website of major schools; University of New South Wales, Melbourne University, Queensland University of Technology and the Australian National University. To study in other countries; visit the university’s website that offer postgraduate degree in optometry.

Contacts: Contact by email or phone to the staffs of the Graduate Research and Scholarships Offi ce for assistance and advice and also fi nd publications available on the Graduate Research and Scholarships Offi ce Website. This contact should be established almost 6 to 12 months in advance if anyone is aiming to study in the next year.

Prospective students should write an email to postgraduate coordinator or administrative offi cer in school or the institute to know the current and future projects and


possibilities in getting scholarship. Sometime some projects are funded that covers students’ scholarship as well.

This contact can be made directly to professors in optometry school expressing the interest. Also contact to seniors, who are useful source to inform you about the projects and help to fi nd the supervisor. Apart from this also collect possible information from offi cial website before seeking further assistance from them.

IELTS (TOFEL) requirement: Students seeking to enroll in postgraduate degree should have IELTS score of 6.5 or above. In some universities, requirement can be higher, therefore it is suggested to check 6 months in advance to ensure that students have enough time to repeat exams if unsuccessful. It is recommended that students must have an IELTS exam before processing an application. However, in some circumstances, English requirement can be waived by the university. This usually applies for students from English speaking country. For details, students must check in the university’s websites or ask to the postgraduate coordinator.

Research topic or area: Students should prepare by thinking, reading and talking with others about research projects and area. They can determine to get into specifi c research area or may become fl exible with range of area of interests. Sometimes it may be required to write a research proposal and submit to the proposed supervisor or to the school before applying for admission. Always investigate and consider the resources, support and supervisors available in optometry school or associated institutions website.

Supervisors: Before the admission application, students should fi nalize under whose supervision they are going to study. For this, students need to fi nd supervisors (professors) name and their project areas in school’s or institute’s website. It is advised to write to those faculties and fi nalize the main supervisor before preparing for formal application. Students may request many professors at same time and confi rm with one with whom they are comfortable and the scholarship is possible. It is always good to approach at a time to many universities and later confi rm with one university where it is likely to receive good scholarship and research project. For UNSW, choose possible supervisors from the list of academic staffs published in school’s website: www.optom.unsw.edu.au

In some occasions, postgraduate coordinator or supervisor would like to make a teleconference with prospective

students. Students must always give landline numbers instead of cell phone and also alternative numbers. If this call is missed once, the opportunity may open another person’s luck. Be ready with clear idea and purpose of the study in the subjects you are interested in.

Processing the application:

Prospective students will process the application only after they fi nalize the project supervisor because this is most essential condition of the universities to consider any application. Once somebody permits or accept for PhD project, students have to fi ll in the application form and send it to the university address within specifi ed deadline. While sending application, students should send a completed scholarship application form together, if wished to apply for this. For scholarship given from other organizations like AusAID, scholarship application should be sent to the concerned organization even before applying for admission. In every institution, an application fee applies. In some scholarship awards, such fees and travel costs are also reimbursed by scholarship scheme. Here are some tips to make your application strong:

Start your preparation very early (six to one year) before you wish to apply

Students also often forget to sign the form or leave out the key sections of the form. Incomplete forms will take much longer for universities to process and respond quickly.

Your academic ability might be clear from your transcripts and references, but you should refl ect your plan, purpose and sometime a research proposal, if supervisor asks.

You must provide two or three referees letter supporting you and explaining your knowledge/ skills, team work, personal behavior and research ability. For these references, try to get from three different sources. One from your Optometry lecturer/ professor, another from your current employer and last if required, get that from your high school / college teacher who better knows about you.

You must have an IELTS score above 6.5 usually.

To success in the competition, your application must be strong enough than others. You must demonstrate research skill that you have and also show them your interest in conducting research in your area of interest.


You must submit a personal statement and background experiences. This may be refl ected by submitting your CV.

Scholarship and admission also depend on the academic merit. But this is not the only indicator for selection. If you have given strong evidence that you are capable to conduct research, you are likely to get offer easily. For this, it is always good to have at least 2 or 3 published journal articles as an evidence to prove your ability that you can conduct research and write scientifi c papers. Presentations in the conferences are also marked as evidence.

It is also good to establish a relationship with faculties and potential supervisors meeting them in conferences and showing interest on research they have been conducting. These relations are much stronger references to get the project and scholarship. Conferences are also helpful in knowing the updates of current work and projects that may interest you to apply in.

Once a student gets selected, university will send him/her an offer letter for admission. Meantime, university also

notifi es whether the person is offered with the scholarship. Once the offer letter for admission is received, process visa application as early as possible. Visa process often takes longer time so you must apply 2 months before the academic session starts.

To conclude, Nepalese optometrists are most likely to get admission in postgraduate degree anywhere in the world, if they prepare in advance with strong application. There is no deadline to enquire and process the application for enrolment in postgraduate degree in UNSW and other universities. You only need to meet the deadline of scholarship application. Finally, good luck to those who wish to apply for graduate research degree sooner or later.

Author Correspondance Prakash Paudel

School of Optometry and Vision ScienceUniversity of New South Wales

Sydney Australia E-mail: [email protected]



Importance of Central Corneal Thickness in Intra Ocular Pressure MeasurementMadhu Thapa, MD

Measurement of intra ocular pressure (IOP) is one of the routine procedures carried out in ophthalomology practice. It is the important parameter in detection and monitoring of glaucoma.

There are various instruments developed for measurement of IOP. Goldman applanation tonometry was introduced in 1954 and is the gold standard for IOP measurement. Goldman and Schmidt, in calibration of applanation tonometer, assumed a standard corneal thickness, was believed that signifi cant variation in corneal thickness was uncommon, but emphasized that corneal thickness would infl uence the reading. Principle of tonometry is based on Imbert-fl ick’s law which asserts that the pressure inside liquid fi lled sphere can be determined by measuring the force required to fl atten the surface of sphere. Thus the pressure inside the sphere is equal to force exerted per unit area of sphere; i.e

P=f/a (p-pressure exerted,f-force applied,a-area)

Other newer technology like non contact tonometer which measures IOP with jet of air hitting the cornea without touching the corneal surface. Other instrument like tonopen, perkins tonometer, indentation tonometer are also used.

Recent literatures have shown that IOP measurement is also dependent on central corneal thickness (CCT) .Researches recognized CCT as an intrinsic ocular factor in pathogenesis and progression of glaucoma. Though the increased IOP is thought to be just a risk factor for glaucoma but in routine clinical practice, measurement of IOP is important in detection and monitoring of glaucoma. So, for accurate measurement of IOP, measurement of central corneal thickness is also mandatory. Abnormal CCT may lead to inaccurate IOP measurement, which may infl uence the treatment of glaucoma as well. It helps to decide if patient really needs treatment or could be kept under observation before the defi nite damage occurs in glaucoma. There are two main issues to be addressed now:

1) Is CCT independent risk factor for development of glaucoma?

2) Does the thickness of cornea infl uence the IOP measure?

For the fi rst question, there is no evidence till date that CCT being thin has any role as to the development of glaucoma. But there is ample evidence that show the CCT do infl uence the measurement of IOP.

CCT can be measured using pachymeter and the procedure is called as pachymetry. Pachymeter could either be optical or ultrasonic. Normal CCT is between 537 to 554micrometer.Increase in CCT may give rise to high IOP and decrease in CCT give rise to decrease in IOP. IOP measurement after PRK, LASIK may be reduced because of the reduced CCT which occurs after the procedure. For every 10 micron difference in CCT, there may be 0.5mmHg difference in IOP measurement i.e 100microm change in CCT may give rise to 5-7 mmHg difference in IOP reading. Distribution analysis of CCT measurement revealed that the largest cluster of African American patient had around 520 to 540 microns, whereas the cluster of Caucasian patients had between 580 to 600 microns

CCT measurement is mandatory in all cases of normotensive glaucoma (NTG), ocular hypertension (OHT) and glaucoma suspect cases in which clinical signs do not correlate with IOP reading. But even in all types of glaucoma measurement of CCT is important to fi nd out the accuracy of IOP measurement. For example, In cases of NTG, patients may have glaucomatous optic nerve damage but still IOP could be recorded as normal which in turn may delay the initiation of treatment, until CCT is checked which may be lesser than normal. Conversely, In case of OHT, patient may have thick CCT which gives rise to falsely high IOP and could be misdiagnosed as a case of glaucoma.

So, in glaucoma suspect case, if patient has thick cornea there will be lesser risk of glaucomatous optic nerve damage because they will have higher IOP and glaucoma evaluation will be done and detected early. In patients who have low IOP due to thin CCT, IOP underestimation could lead to sever optic nerve damage before detection. Studies have also shown that patient with pseudoexfoliation glaucoma also has thinner CCT as compared to normal.

So, during evaluation of all the cases of glaucoma and glaucoma suspect, CCT measurement should be carried out routinely. This not only helps to estimate the IOP correctly but also helps in correct diagnosis and proper management.

Author Correspondance Dr. Madhu Thapa

LecturerMaharajgunj Medical Campus

BP Koirala Lions Centre for Ophthalmic StudiesMaharajgunj Kathmandu



Post keratoplasty Astigmatism – Practical Management Meenu Chaudhary, MD

Corneal transplantation has become a very suc cessful procedure due to advances in eye banking, corneal surgery and postoperative treatment. Astigmatism remains a major obstacle for visual rehabilitation after penetrating keratoplasty. A postoperative clear cornea with high and/or irregular astigmatism following penetrating keratoplasty (PKP) can no longer be considered a surgical success. A variety of factors affect postoperative astigmatism, including disparity between donor button and recipient

bed, graft diameter, malposition of donor and recipient corneas, underlying diagnosis of the recipient, wound confi guration abnormality and the suture technique involved .

Factors directly related to the morphology of the wound during trephination are most likely to have the most impact on the long-term persistent astigmatism after PKP. Short-term astigmatism is mostly determined by the asymmetry of the sutures.

Table 1: Preoperative determinants for astigmatism after PKP

Table 2: Intra-operative determinants for astigmatism after PKP

• Donor age • Size of patient's cornea

Keratoconus>Fuchs' dystrophymicro cornea

• Donor topography • Recipient topography • Disharmony between donor and recipient topography • Pathologic properties of the patient's cornea

peripheral thinning or ectasiafocal edema or scardefects of Bowman's layerdegree of vascularizationprevious PKP or other corneal surgery

• Pseudophakia / aphakia

• Decentration of donor and/or recipient trephination • “Vertical tilt” due to discrepancies of wound

confi gurationApplication of different trephination techniques in donor and recipient Tilt of the trephine away from the optical axisLimbal plane not horizontalCreation of steps due to change of trephination directionHigh/low intraocular/intracameral pressureOverlap of dehiscence due to vertical cut incongruence

• “Horizontal torsion”Asymmetrical placement of second cardinal sutureUnfavorable alignment of the graft due to horizontal shape incongruence

• Excessive over-/under sizing of the donor • Distortion and squeezing of the cornea (for example,

dull trephine) • Traumatizing of the cornea by surgical instruments • Suture-related factors

Suture materialSuture technique (single, running, double running, combined)Suture lengthSuture angle relative to graft-host-junctionSuture tension“Depth disparity”

• Simultaneous intraocular interventions (triple procedures, IOL exchange, etc.)

• Fixation rings and lid specula • Surgeon’s experience


Table 3: Postoperative determinants for astigmatism after PKP

Table 4: Advantages of non-mechanical trephination with the 193 nm excimer laser

• Suture-related factors"Cheese wiring" of suturesSuture looseningSuture adjustment/selective suture removalTiming of suture removalSequential or all-at-a-time suture removal

• Wound healing processesWound dehiscenceRetrocorneal membraneIncarceration of overlapping cut edgesFocal vascularization

• Medication (for example, corticosteroids) • Postoperative trauma

• Avoidance of trauma to intraocular tissues • Avoidance of radial and tangential forces effecting

tissue “squeezing” • Reduction of horizontal torsion (“Erlangen orientation

teeth”) • Reduction of vertical tilt (“perfect” congruent cut

surfaces of donor and recipient) • Reduction of recipient and donor Decentration • Potential for “harmonization” of donor and recipient

topography • Reduction of anterior chamber infl ammation early

after keratoplasty • Reduction of astigmatism after suture removal • Higher regularity of topography • Signifi cantly better visual acuity • Potential of trephination in the “open eye” (for

example, perforated corneal ulcer)

Table 5: Potential methods for correction of astigmatism after PKP

Optical methodsspectacles contact lenses combinationsSurgical methodsIntra-operative wound manipulation type of trephine (include laser) placement of trephination confi guration of trephination size of donor/recipient trephinationIntra-operative suture manipulation type of suture localization of suture length/depth of stitches suture tensionPostoperative wound revision opening, re-adaptation, new suture relaxing incisions in the graft-host-junction (with/without compression sutures) sutured wedge resectionsPostoperative suture correction selective single or double running suture removal adjustment of a (double) running suture additional suturesTransverse keratotomies inside the graft Limbus parallel or straight combination with radial incisions combination with compression sutures combination with cataract extractionLaser ablation (preferably topography-based) PRK LASIKThermokeratoplasty (holmium:YAG laser)Deep-lamellar re-trephination with/without new sutureRepeat keratoplasty with greater diameter (preferably with laser trephination)

Relaxing incisions

Troutman estimated that nearly 10 percent of all clear penetrating keratoplasties was complicated by high postoperative astigmatism. Symmetrical relaxing incisions placed 180° apart produced 0.78 D of astigmatism change for one clock-hour incisions and 13.97 D of change for sym metrical three clock-hour incisions. Clinically, Lavery and Lindstrom found that the relax-ing incision technique effectively fl attened the steeper meridian an equivalent amount as it steepened the fl atter meridian. The major complication of this procedure is poor predict ability. As refractions in keratoplasty patients are often quite diffi cult and inac curate, one has to rely primarily on keratometry and retinoscopy when planning procedures. An appropriate incision length should never exceed three clock-hours or 90 0 of the circumference of the graft. The incision length and depth may vary, de pendent upon the variability in wound healing as it contributes to astigmatism. In traoperative keratometry is especially helpful to deter mine a proper endpoint of the relaxing incision. Progressive deepening and lengthening of the incision is performed initially on one side of the graft-host inter face while continuously observing the keratometeric mire for correction of the astigmatism. Gradual deepening and lengthening of the incision is then made 180 0sub to the fi rst incision until an overcorrection is achieved by use of the surgical keratometer.

Compression sutures

If the relaxing incisions do not attain an adequatecor-rection of astigmatism, compression sutures may be placed


Assessment

Careful evaluation of tight sutures, and sometimes the fl at and steep axes of a graft can be done by slit lamp examination. Manifest refraction, retinoscopy, kerat-ometry, Placidoring keratoscopy and computerized videokeratoscopy (corneal topography) are all valuable techniques for assessing post-graft astigmatism.

Management

Glasses and contact lenses: Spectacle correction of astigmatism is often tolerated upto about 4 diopters of cylinder. Above this level, rigid gas permeable contact lenses may be necessary for satisfactory correction .Reverse geometry RGP may be necessary to ensure a satisfactory fi t.

Selective Suture removal: Selective suture removal has been shown to hasten visual rehabilitation. Keratometry, photokeratoscopy, slit-lamp examination and manifest refraction help identifi cation of any tight sutures. Selective suture removal begins at about 6 weeks and only one or two sutures are removed at one time. The cornea is evaluated every 2 weeks for change in contour and further sutures are removed.

Surgical Management

In situations where signifi cant astigmatism continues to be an obstacle to visual rehabi litation, more drastic methods of wedge resection, wound revision and repeat keratoplasty may have to be considered. It is important to individualize and modify the planned surgery based on qualitative keratoscopy and corneal topography for the initial and subsequent astigmatic corrections. If astigmatism is still present at the end of 8 to 9 months, incisional arcuate keratotomy in the wound or inside the wound is planned in the steeper meridian which corrects 4-6 D of astigmatism. The incision length and depth should vary; depending upon the type of wound healing that has yielded the astigmatism. Intraoperative keratometry helps to optimize the grading of length and depth of the incision according to the effect achieved during the surgical procedure. Progressive deepening and lengthening of the incision is performed fi rst on one side and then on the other side until Keratometer mire is assessed to be spherical. It is not necessary to overcorrect. Additional compression sutures in the fl atter meridian may be employed to enhance the effect. When indicated, radial incisions on the graft may be performed in combination with intraincisional relaxing incisions or arcuate incisions.

on each side of the graft-host interface 90° away from the relaxing incisions. Suture depth should be approximately 75%. These sutures are tied with a slip knot and adjusted under keratometric control until an overcorrection of 33 to 50% is achieved. The use of mersilene suture is preferable because, if perfect surgi cal correction of astigmatism is achieved, it may be desirable to leave the suture in place for extended periods of time where as nylon will hydrolyze in 1-2 years, mersilene suture will last greater than 7-10 years.If overcorrection persists at 8 weeks after placement of compression sutures, one of the sutures is removed. If overcorrection still persists, the second compression suture is removed at 12 weeks. If an inadequate surgical correction is achieved, the operation may be repeated, or an alternative procedure such as wedge resection or astigmatic keratotomy may be considered.

Wedge resection

The wedge resection technique is reserved for correc-tion of large degrees of postkeratoplasty astigma tism. In general, resection of 0.10 mm of tissue results in approximately 2 diopters of astigmatic correction. This operation is reserved for patients with greater than 10 D of astigmatism. This technique is readily capable of correcting up to 20 D of astigmatism. Wedge resection, however, requires a prolonged pos toperative rehabilitation. The long visual rehabilitation is necessitated by the placement of multiple sutures which induce signifi cant irregular astigmatism and adequate wound healing must be allowed before selective suture removal can be undertaken to reduce the irregular astig matism prior to eventual visual rehabilitation. Neverthe less, the alternative to wedge resection in such patients is repeat penetrating keratoplasty and, therefore, an attempt at wedge resection appears preferable to imme diate repeat keratoplasty.The overall effect of wedge resection is to steepen the fl atter meridian approximately twice as much as it fl at-tens the steeper meridian. The net effect is an increase in myopia or decrease in hyperopia following this proce-dure.

Astigmatic Keratotomy

Astigmatic keratotomy incisions include transverse in cisions, semi radial incisions or the combination of the two which describes the trapezoidal astigmatic keratotomy popularized by Ruiz. The axis of plus cylinder measured refractively or the steeper meridian measured keratometrically should be identifi ed in order to direct the placement of semi radial or transverse incisions.


Transverse incisions are placed perpendicular to the steeper meridian, and are indicated for the correction of low degrees of astigmatism. These incisions fl atten the steeper meridian an equivalent amount as they steepen the fl atter meridian. Therefore, the net effect is no change in spherical equivalent. Studies of radial keratotomy have shown that the closer radial incisions get to the optical axis, the greater the effect on corneal fl attening. Transverse incisions placed more central than a 5 mm optical zone are to be avoided as they are less effective, induce more glares and carry a greater risk of inadvertently violating the visual axis. A single transverse incision placed 7 mm apart corrects approximately 0.75 diopters of astigmatism, whereas a pair of transverse incisions placed 7 mm apart corrects 1.0 diopters. Therefore, the desired effect may be varied by either the optical zone placement or the length of transverse incisions. The appropriate optical zones range from 5-8 mm and transverse incision length should range form 2.5-4 mm.

Semi radial incisions

Semi radial incisions have been described as lines placed halfway between a true radial line drawn from the optical zone and a line drawn perpendicular to the transverse incisions. There fore, semi radial incisions alone may correct modest amounts of astigmatism.

Modifi ed ruiz procedure

Semiradial incisions combined with transverse incisions describe the trapezoidal astigmatic keratotomy popularized by Ruiz. This procedure was initially designed to include 2 sets of semiradial incisions and 5 sets of equally spaced transverse incisions. Maximal correction of astigmatism may be attained with only a single set of transverse incisions placed 5 mm apart between two sets of semiradial incisions made from a 3mm optical zone. Mild additional

effect may be achieved in post-keratoplasty cases by adding a second pair of transverse incisions coincident with a 7 mm or 9 mm optical zone, between the semiradial incisions.

Conclusion

Astigmatism remains a major obstacle for visual rehabilitation after penetrating keratoplasty and hence, management of astigmatism is an essential part of visual rehabilitation. The correction of postoperative astigmatism is now an excit ing area of refractive surgery including LASIK, where the understanding of the principles and the potential for improved predict ability continues to evolve rapidly.

References

1. San Jim Kim etal, Journal of Korean medical Sciences 2008; 23:1015-9.

2. Astigmatism after keratoplasty: prophylaxis and therapy. Refractive surgery, Ocular surgery news U.S. Edition, September 15, 2000.

3. Management of post keratoplasty astigmatism Riddle HK Jr etal.Current opinion ophthalmol 1998 Aug; 9(4):15-28.

4. Postoperative management of corneal graft, Jagjit S Saini, Indian J Ophthalmol 1994;42:215-7

5. Surgical correction of postoperative astigmatism, Richard L Lindstrom, Review article 2010 ;38 (3) : 114-123

Author Correspondance Dr. Meenu Chaudhary

LecturerMaharajgunj Medical Campus

BP Koirala Lions Centre for Ophthalmic StudiesMaharajgunj Kathmandu

E-mail:[email protected]



Intraocular Lenses for Near VisionJit B Ale, B.Optom.

Introduction of intraocular lens (IOL) dates back to 1949 with the fi rst implantation performed by Sir Harold Ridley. Since mid 1960s, the IOL became popular and subsequently received FDA approval in 1977 (Milton Roy Co. Analytical) for the fi rst time.1 Today virtually all cataract patients have the benefi t of IOLs and its implantation has become a standard method of visual rehabilitation following cataract removal. Today, cataract surgery is no more a mere cataract removing procedure but it has become a regular component of the refractive surgery.

Earlier designs though were far from perfect; it worked well enough to encourage further refi nement. Improvements in design technology now approach perfection, and safety is virtually guaranteed. Traditional IOLs offer clear focus only for an object located at a specifi c distance. An eye implanted with such IOL therefore requires supplementary correcting device such as spectacle or contact lens to enjoy clear vision at various viewing distances. Improved versions of the monofocal IOLs are aspheric IOLs which improve the retinal image quality by eliminating or partially correcting the ocular aberrations but these do not enhance the near vision.

Constantly rising demand for long term post-operative precise vision has lead to proliferation of more sophisticated surgical techniques and novel IOL designs. Consequently, quest for IOL technology offering optimum near vision among pseudophakic patients and also concurrently preserving good cosmoses is on its peak. Some surgeons attempted a technique of myopization of one eye by implanting the IOL power calculated for near vision 2; also called monovision technique. Though this technique is cosmetically acceptable, due to the loss of binocularity, it may not be suitable particularly for the professionals requiring intact binocular vision.

Developments in multifocal IOLs, often called pseudoaccommodative IOL (PIOL), represent the early attempts to improve near vision for pseudophakic

presbyopes. These IOLs employ multiple optical zones or power progressions (e.g. ReZoom, Advanced Medical Optics) or zones with diffractive optics (e.g. ReStore, Alcon) to simultaneously provide near and distance images on the retina. Though post-operative spectacle independence has been reported3, due to the simultaneous presentation of images for a range of viewing distances to achieve near and distance focus, these devices typically compromise on some aspects of visual performances including subjective vision complaints such as glare, halos, poor contrast and ghosting4. But a major weakness of such devices is not being able to reproduce continuously variable change in focus afforded by natural accommodation and enjoyed by the pre-presbyopic eyes.

Ahead of these developments, accommodating IOLs (AIOL) have emerged with rapid progress in development. AIOLs change their power directly either by changing the curvature (deformable or dynamic optics AIOL) or by altering their relative axial position within the eye (translating-optics AIOL). Deformable optics AIOL; e.g. NuLens is yet to be introduced; however, translating-optics AIOLs which are prominently represented by variants of single-optic or dual-optics AIOLs, already have some clinical experience. At least one design of dual-element AIOL (Synchrony, Visiogen, Irvine, CA) is being introduced which is under the second stage of clinical trial. One more design, Sarfarazi IOL was reported in 2006, but the development has been abandoned. Single-optic AIOL has more than a decade of experience in Europe. Crystalens AT-45 (Eyeonics, Inc. CA), Kellan Tetrafl ex (KH_3500, Lenstec, FL, USA), OPAL (Bausch& Lomb, Rochester, New York), C-Well (Yehuda, Israel), BioComFold (Morcher) and TekClear (Irvine, California, USA) are some of the AIOLs commercially available5.

Studies reporting the accommodative performance of such AIOLs are equivocal. Subjective and objective amplitude of accommodation of single-optic AIOL is reported to be as high as 3.24D and 1.0D respectively6. Obviously, the subjective method would have over-estimated the performance; therefore these cannot be fully relied on.


Theoretically, as much as 1.25D accommodation is obtainable with this type of AIOL provided it translates at least by 1 mm7. Interestingly enough, theoretical prediction and the clinical performance based on objective method concord well. Interpretation of the clinical outcome and success of single-optic AIOL is debated. Principally, a dual-optics AIOL are more promising compared to the single-optic AIOL in terms of accommodative performance. To the author’s knowledge, only one clinical study has reported the accommodative performance of two-optics AIOL which found about 3.5D accommodation. Theoretical studies predict that this type of AIOLs offer 2.5 to 4.0D accommodation per millimeter translation of the optics depending on the design and confi guration7-8.

Search of technology that may offer adequate amount of accommodation without much complexity and having ability to preserve natural eye accommodation without compromising other aspects of optical properties is ever increasing 9. The concept of replacing less deformable lens matrix with comparable soft transparent polymer dates back to 1964 when Kessler attempted to refi ll the evacuated lens capsule with a transparent substance and conceptualized that the accommodation can be preserved with elastic and viscid fi ller10. This technique now is named as phaco-ersatz11. Two distinct procedures are attempted within this concept: implantation of infl atable endocapsular balloon fi lled with transparent gel12 and injecting the polymer directly into the capsular bag13.

Experiments on refi lling the aspirated lens capsule with endocapsular balloon in animal eyes have found up to 6 D of accommodation amplitude14 whereas an animal study produced as much as 4.5 D accommodation. A theoretical calculation for amplitude of accommodation by ray tracing in model eyes returned about 10 D of accommodative amplitude with hypothetical polymer of refractive index 1.49 15. The authors believed a loss of intra-capsular accommodation, i.e. active participation of lens fi ber cells in the mechanism of accommodation may affect the accommodative effi ciency of such procedure. Being at the initial stage, there are several issues such as leakage and clouding of the gel are to be addressed before it can be applied in living human eyes.

To conclude, pseudophakic presbyopia has been a long standing visual dilemma. Though plethora of methods to overcome this problem has been proposed, only a few appears to be technically appealing. An ideal method of restoring accommodation in the pseudophakic eye would be the one that would mimic natural process of accommodation.

References

1. Apple DJ, Mamalis N, Loftfi eld K et al. (1984). Complications of intraocular lenses. A historical and histopathological review. Survey of Ophthalmology 1984; 29: 1-54.

2. Baikoff G (2004). Surgical treatment of presbyopia: Scleral, corneal, and lenticular. Current Opinion in Ophthalmology 2004; 15: 365-369.

3. Alio JL, Elkady B, Ortiz D & Bernabeu G (2008). Clinical outcomes and intraocular optical quality of a diffractive multifocal intraocular lens with asymmetrical light distribution. Journal of Cataract & Refractive Surgery 2008; 34: 942-948.

4. Manns F, Ho A & Kruger R (2004). Customized visual correction of presbyopia. In: Kruger R, Helmholtz H & MacRae S, editors. Wavefront-guided visual corrections: The quest for super vision ii. 2nd ed. Thorofare, NJ: SLACK Inc. p. 353 - 362.

5. Doane JF & Jackson RT (2007). Accommodative intraocular lenses: Considerations on use, function and design. Current opinion in ophthalmology 2007; 18: 318-324.

6. Wolffsohn JS, Naroo SA, Motwani NK et al. (2006). Subjective and objective performance of the lenstec kh-3500 "Accommodative" Intraocular lens. British Journal of Ophthalmology 2006; 90: 693-696.

7. Ale J, Manns F & Ho A (2010). Evaluation of the performance of accommodating iols using a paraxial optics analysis. Oph Physiol Opt 2010; 30: 132 - 142.

8. Ho A, Manns F, Therese & Parel JM (2006). Predicting the performance of accommodating intraocular lenses using ray tracing. J Cataract Refract Surg 2006; 32: 129-136.

9. Glasser A (1999). Can accommodation be surgically restored in human presbyopia? Optometry & Vision Science 1999; 76: 607-608.

10. Kessler J (1964). Experiments in refi lling the lens. Archives of Ophthalmology 1964; 71: 412-417.

11. Parel JM, Gelender H, Trefers WF & Norton EW (1986). Phaco-ersatz: Cataract surgery designed to preserve accommodation. Graefes Archive for Clinical & Experimental Ophthalmology 1986; 224: 165-173.

12. Nishi O, Hara T, Sakka Y et al. (1991). Refi lling the lens with infl atable endocapsular balloon. Developments in Ophthalmology 1991; 22: 122-125.


13. Haefl iger E & Parel JM (1994). Accommodation of an endocapsular silicone lens (phaco-ersatz) in the aging rhesus monkey. Journal of Refractive & Corneal Surgery 1994; 10: 550-555.

14. Sakka Y, Hara T, Yamada Y, Hara T & Hayashi F (1996). Accommodation in primate eyes after implantation of refi lled endocapsular balloon. American journal of ophthalmology 1996; 121: 210-212.

15. Kirchhoff A, Stachs O & Guthoff R (2001). Three-dimensional ultrasound fi ndings of the posterior iris

region. Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie 2001; 239: 968-971.

;'b[li6

Author Correspondance Jit B Ale

University of New South WalesSydney Australia

E-mail: [email protected]



Daily Disposable Contact LensesVipin Buckshey

When Soft Contact Lenses were commercially launched in 1971 every manufacturer of lenses tried to produce a lens, which would last the longest. This resulted in many clinical problems caused by long term usage of the same pair of soft contact lenses. The problems most Contact Lens wearers faced were not because of the lenses but mostly because of the deposits that formed on the lenses. The trend changed from 1988 as the concept s

hifted to “shorter is better” and this lead to the development of disposable and frequent replacement soft lenses. Practitioners all over the world embraced the disposable concept when the distinct advantages were confi rmed by their own clinical observations and reinforced by enthusiastic satisfi ed contact lens wearers.

Recently, a new opportunity has presented which promises to have a greater impact on contact lens wearers than anything that has preceded it. A new generation of disposable contact lenses has been developed known as the “Daily Disposable Contact Lenses”. This has been made possible by a technological breakthrough that advances the state of the art of contact lens manufacturing to an unprecedented level of capacity, quality control and productivity. This latest technology in contact lens manufacturing is called “Maximise” or if simply put it is the new method of mass-producing lenses so cost effectively that daily disposability is affordable. The wearer should be able to get a fresh sterile pair every morning ultimately for the cost of a daily newspaper and a cup of coffee.

This is a Contact Lens that you wear only during waking hours and does not require any care or maintenance. When you remove the lens each day before bedtime, you don’t have to clean and disinfect it because you just throw it away and never wear it a second time. When worn in this manner, daily disposable lenses have a major advantage in terms of ocular hygiene and convenience. The wearer does

not have to go through the hassle of cleaning, disinfecting or enzyming besides having the advantage of wearing a fresh sterile lens every morning. It has generally been seen that contact lens wearers don’t like the hassle and complexity of lens care and are notoriously non-complaint in after care. And, numerous studies have shown that a high percentage of wearers’ store their contact lenses in carrying cases contaminated with dangerous micro-organisms. Besides having advantages of hygiene and comfort the daily disposable contact lenses are also best for occasional wearers. The daily disposable contact lens may have sounded somewhat far-fetched a few years ago, but today this contact lens is a reality. With the development of daily disposable lenses, we are on the threshold of a new era in Contact Lenses, that will not only continue to confi rm that “Shorter is Better” but prove that “Shortest is Best”. If the daily disposable contact lens is priced economically these comfortable, convenient lenses would defi nitely be an excellent non-invasive alternative to Refractive Surgery. Patients may not be eager to have their eyes re-sculpted specially after they learn about this most recent advancement in Contact Lenses.

The major benefi t of these new daily disposable lenses is convenience. The wearer does not need a lens case; a bottle of solution or any other contact lens care products. Manufacturers of daily disposable lenses are very confi dent that the appeal of convenience and the savings in lens care products will attract wearers to this new concept. Candidates for these lenses would include current daily wear soft contact lens wearers & contact lens dropouts who want a deposit and hassle free lens. These lenses would also open the door for many spectacle wearers who may be interested in wearing lenses several times a week. Many of the wearers would enjoy wearing these lenses two or three times a week for sports, social and business events.


In India with high levels of dust and pollution daily disposable soft lenses would be the most ideal form of contact lens wear. As per the new Indian Government trade policy this lens is a freely importable product and is now available with eye care practitioners across the Country. Wearers who defi nitely want the very best for their eyes would go in for these lenses to enjoy the comfort and convenience.

Author Correspondance Padmashree

Vipin BucksheyOptometrist & Contact Lens Specialist

Visual Aids CentreE-18, South Extension Part Two

New Delhi-110049.E-mail: [email protected]



Computer Vision Syndrome- New Millennium DiseaseM R Bajracharya, MD and Kishor Sapkota, B. Optom

Modern science technology has delivered tremendous changes in our life style and civilization. As a double edge sword, it has stipulated some negative impacts among the computer users. From the aspects of physical and mental health, computer is not totally safe among the users.

Computer vision syndrome (CVS) can be defi ned as a series of symptoms and complaints by the computer users after its widespread application without taking necessary precautionary measures. Studies have revealed that 50-80% computer users may experience the symptoms of CVS. Among the adult population, people above the age of forty are prone to the higher risk as it collides with the normal deterioration of vision at that age.

The predisposing factors which may be considered for the origin of CVS are viewing the computer on working distance 20-24 inches, working for long hours from 4-6 hours to 15 hours per day at a stretch typing the keyboard time to time. Besides, the computer users are prone to less blinking then normal leading to the excess evaporation and dry eye.

Patients suffering from the CVS may complain of the symptoms like constant throbbing headache, Ocular fatigue lack of focus in the object, blurred vision double vision burning sensation of the eyes, sometimes the red eye etc.

CVS is of great concern to the mankind in the modern generation. In this context, scientist and health authorized personnel have developed few rules to alleviate the symptoms of cvs.

Get eye examination periodically: if any refractive error like hyperopia, myopia and astigmatism, it will be a great help to reduce some symptoms of CVS after proper correction. Moreover, tear level evaluation, accommodative function test reveal any problems of dry eye and fatigue. Using some tear supplement drop may enhance the comfort. Similarly, simple home eye muscle exercise help the eyes to combat ocular fatigue by preventing from accommodative spasm.

Use proper lighting: eye strain is often caused by excessively bright light either from outdoor sunlight

coming through the window or from computer itself.

Minimize glare using the antiglare screen in front computer. Wearing anti glare or ARC glasses will defi nitely help from glare. Moreover, any unwanted light refl ection coming from window or other means should be barred.

Upgrade display in the computer: from different studies it is found that liquid crystal display are easier on the eyes and usually have an antirefl ective surface. However, if cathode ray tube style monitor is to be used it should have high possible refresh rate and high resolution.

Adjust the brightness and contrast of your computer system: for vision friendly brightness, screen brightness should be similar with the working environment. Text size and the text contrast are also important factors to be considered. Ideally text size should be three times the smallest text size that can be read on normal viewing distance. It is also recommended that black letter on white background or vice verse is the best colour combination as it has the greatest contrast.

Blink your eyes in short interval: the normal blink rate is 10-20 times per minute; however it is reduced up to one fi fth of normal when people work on computer. So tear coating the eye evaporate more rapidly during long non blinking phases and cause dry eyes. Use of air conditioning even enhances this effect. Increasing blink rate consciously and using some tear supplement eye drop help very much. Furthermore eye exercises like 20-20 rule is worth doing.

Take the frequent breaks during computer work: to reduce risk for computer vision syndrome and neck, back and shoulder pain user should take frequent breaks. Two 15-minute breaks and four 5-minute mini breaks are necessary each day.

Modify your work station: improper posture during computer work also contributes to computer vision syndrome. So ergonomically suitable furniture should be used.


Consider for computer eye wear: a special power computer glass is necessary for computer users as screen distance is neither too close nor too far.

In conclusion although CVS is an emergency health related problem worldwide, vision symptoms in CVS related symptoms can be easily alleviated by the good eye care and by change in the work environment. It does not disable the sufferer for life.

1. 2001 Mrs. Pooja Pradhan Optometrist, Australia [email protected]. 2001 Mr. Raju Sapkota PhD Student, Scotland [email protected] 3. 2001 Mr. Ram Chandra Lamichhane Optometrist, Private Practice, Kathmandu [email protected] 4. 2001 Dr. Santosh Khanal Research Consultant, Austraia [email protected] 5. 2001 Mr.Prakash Paudel PhD Student,Australia [email protected]. 2002 Dr. Jyoti Khadka PhD, UK [email protected]. 2002 Mr. Mahesh Raj Joshi Student, Norway [email protected]. 2002 Dr. Subhod Gyawali MPH, BP Eye Foundation, Kathmandu [email protected] 9. 2002 Dr. Santosh Upadhyaya Optometrist, Maldives [email protected] 10. 2002 Mr. Gauri Shankar Shrestha Teaching Assistant, IOM Kathmandu [email protected] 11. 2002 Mr. Govinda Pangeni PhD Student, Germany [email protected]. 2003 Mr. Dipendra Shah Optometrist, BPKIHS Dharan [email protected]. 2003 Mr. Rabindra Ghising Optometrist, Canada [email protected]. 2003 Ms. Anju Shresth Optometrist, Student Cyprus [email protected] 15. 2003 Ms. Sandhya G.C M.Optom. Student, Australi [email protected] 16. 2003 Mr.Hari Bahadur Thapa Optometrist, LEI, Bhairahawa [email protected] 17. 2004 Mr. Asik Pradhan Optometrist, Maldives [email protected] 18. 2004 Mr. Kishor Sapkot Optometrist, NEH, Kathmandu [email protected] 19. 2004 Dr. Purushottam Dhungana Opotmetrist, TEI, Kathmandu [email protected] 20. 2004 Mr.Ramesh Gautam M.Optom. Student, UK [email protected] 21. 2004 Mr.Sanjeev Mishra M.Optom. Student,India [email protected] 22. 2004 Dr. Sanjeev Bhattarai Teaching Assistant,IOM [email protected] 23. 2006 Mr.Prakash Adhikari Instrutor Optometrist,IOM [email protected] 24. 2006 Mr.Niraj Dev Joshi Instrutor Optometrist,IOM [email protected] 25. 2006 Mr.Govinda Ojha Otpometrist, TEC, Kathamandu [email protected] 26. 2006 Mr.Shyam Panthi Optometrist [email protected] 27. 2006 Mr.Suresh Awasthi M.Optom. Student, Norway [email protected] 28. 2007 Mr.Deepak Rana Optometrist, Maldives [email protected] 29. 2007 Mr.Digen Sujakhu Optometrist, MECC, Jhapa [email protected] 30. 2007 Mr.Dinesh Kafl e Optometrist, NMC, Kathmandu kafl [email protected] 31. 2007 Mr.Ravin Mishra M.Optom Student, India [email protected] 32. 2008 Mr.Ajit Thakur Optometrist, SCEH, Lahan [email protected] 33. 2008 Mr. Deependra ku. Sha Optometrist, NMC, kathmandu [email protected]. 2008 Mr. Gopal Bhandari Optometrist, Bharatpur Medical College [email protected]. 2008 Mr. Jeewananda Bista Optometrist, Maldives [email protected]. 2008 Mr. Nabin Paudel Optometrist,BPKLCOS, Kathmandu [email protected] 37. 2008 Mr. Sanjay Marasin Optometrist, Dhulikhel Hospital, Kavra [email protected] 38. 2009 Mr. Arun Dhungana Optometrist,GEH,Biratnagar [email protected] 39. 2009 Ms.Fathimath Nestha Md Optometrist, Maldives [email protected] 40. 2009 Mr.Dipesh Bhattarai Optometrist,BEF, Kathamdnu [email protected] 41. 2009 Mr.Nabin Raj Joshi Optometrist, KMC [email protected] 42. 2009 Mr. Man Bdr. Kuwar Optometrist, OM Hospital [email protected]. 2009 Mr.Ravindra Adhikary Optometrist, REMEH, Banepa [email protected] 44. 2009 Mr.Rajendra Gyawali Optometrist,NMC THRC,Biratnagar [email protected] 45. 2010 Mr. Himal Kandel Final Yr Student,IOM [email protected] 46. 2010 Mr. Mahesh K. Dev Final Yr Student,IOM [email protected] 47. 2010 Mr. Mezbha Uddin Final Yr Student,IOM [email protected] 48. 2010 Mr. Raju Kaiti Final Yr Student,IOM [email protected] 49. 2010 Mr. Sonisha Neupane Final Yr Student,IOM [email protected] 50. 2010 Mr. Suman Adhikari Final Yr Student,IOM [email protected] 51. 2010 Mr. Suraj Upadhyaya Final Yr Student,IOM [email protected]

Graduate Optometrists from Institute of Medicine (IOM), TU2001-2010

Author Correspondance Kishor Sapkota

OptometristNepal Eye Hospital

Tripureshwor KathmanduE-mail: [email protected]



Keratoconus: Meaning and Options Today Rajesh Wadhwa, M. Optom, FIACLE

Keratoconus is a disorder of the anterior surface of the eye (the cornea). In simple terms this means that the cornea bulges from its normal round shape to a cone shape and also becomes thinner. This bulging interferes with a person's vision and can severely affect the way they see the world making simple tasks like reading, watching TV or driving very diffi cult. The distortion caused by keratoconus has been compared to viewing a street sign through the car windscreen while driving through a rainstorm.

Due to the irregular cornea, visual acuity with spectacles is sub-normal. As the disease progresses, the cornea thin and changes shape. At some point glasses and contact lenses may no longer provide the best possible vision and other methods of treating keratoconus must be used.

The progression of keratoconus is unpredictable but generally the condition progresses slowly and can cease at any stage. While keratoconus interferes with the clarity of a person's sight it rarely causes blindness and in its early stages, keratoconus causes slight blurring and distortion of vision and increased sensitivity to glare and light. As the disorder progresses, the degree of vision obtained through spectacles becomes less acceptable and contact lenses often become the best method of correcting vision problems.

Keratoconus typically commences at puberty and progresses to the mid thirties at which time progression slows and often stops. Between age 12 and 35 it can arrest or progress at any time and there is no way to predict how fast it will progress or if it will progress at all. In general young patients with advanced disease are more likely to progress to the point where they may ultimately require some form of surgical intervention.

Most people can successfully manage their condition using special keratoconus contact lenses, however in a small number of cases where the cornea can no longer successfully be fi tted with contact lenses,have to go for other methods.

Having confi rmed the diagnosis of keratoconus, the issue is “What can we do for the patient?” It is wise to proceed in following order.

In order to arrest the progression, we must catch the patient early. The best approach is to fi rst evaluate if adequate corneal thickness (minimum 450 μ) is present. This level of thickness permits the C3R procedure of collagen cross-linking. If successfully performed, the cornea gets a better backbone. This is expected to limit the progress of cone. In some cases regression of cone has been observed after C3R procedure.

In early stage keratoconus, distortion of vision can be treated using spectacles to correct minor myopia (nearsightedness) and astigmatism caused by the condition.

As keratoconus advances, gas permeable (GP) contact lenses are the fi rst choice to correct vision. The fi rm material of rigid contacts can maintain the spherical shape of the eye and allow for more focused vision. A conventional RGP lens may achieve good vision. Most of the times, this is a permanent remedy. Problems like apical staining on bearing area, distorted images and lens dislocation exist in these lenses. Specialized RGP lenses that reduce these problems are available for keratoconus. Lenses like Rose K have been around for about a decade and are now the most popular lenses for keratoconus, the world over.

Rose K Lens:

The Rose K™ lens has a number of features that make it ideal for keratoconus and is internationally recognized as the leading lens for the treatment of keratoconus.

• The complex geometry of Rose K™ lenses take into account the conical shape of the cornea in all stages of the condition.

• Rose K lenses are designed using complex computer models and manufactured on special computerized lathes.

• These lenses can be customized to suit each eye and can correct the myopia and astigmatism associated with the condition.

• Rose K™ lenses allow the cornea to 'breathe' oxygen


directly through the lens material providing excellent health to the eye.

• The lenses are easy to insert, remove and clean.

• Accurate repeatability.

The difference between regular RGP and Rose K lenses can be visualized by studying the following two comparative diagrams:

Standard lens designs with fi xed optical zones (OZ) do not ideally fi t the cone shape of keratoconus patient's. Figure shows a standard lens that will yield unwanted pooling at the base of the cone and peripheral bearing that can seal off and cause corneal problems.

ROSE K demonstrates the benefi ts of a smaller optical zone to fi t the cone contour. The design results in little tear pooling at the base of the cone and shows an even distribution of tears under the lens.

With normal corneas, the shape does not change dramatically from the center to periphery. The change tends to be even and in predictable amounts. Therefore, with normal corneas the back surface of the lens can be designed with small incremental changes (e.g. eccentricity) over most of the lens with a peripheral curve at the edge. Usually this will achieve reasonable alignment with the cornea and a good fi t. In keratoconus, this kind of smooth and predictable corneal shape is absent.

Dr. Paul Rose further refi ned the Rose K™ lens to take into account the unusual corneal shape of keratoconus patient's, which require abnormal curves on the back of the lens to fi t the cornea optimally.The Rose K™ system has pre-set optical zones to maximize vision while maintaining good corneal health. Due to steep curvature of these lenses, aberrations were high.

Now Rose K is upgraded to Rose K2 that minimizes the aberrations. In an attempt to bring the light passing through the lens within the pupil zone to a single point, very small changes were applied to the curves on both the front and back of the lens. This resulted in unique “aberration control” of the Rose K2 lens.

A well-fi tted Rose K2 lens often results in an overall good and acceptable fi t. This includes better comfort and optimum visual acuity (sharpness) for patients. However, due to the progressive nature of the condition, it is important that lenses are fi tted with great care and an annual follow up be done by the eye care professional

Procedure is simple:

- Patient needs to come for trial (1.5 hours) and then after 2 weeks for delivery (1 hour again).

-The fi nal lens has vision identical to the trial lens. Comfort and stability are better than the trial lens.

Mini Scleral Design (MSD) is a lens that vaults over the cornea and has bearing on the sclera. These are reasonably priced and fi tting time is similar to Rose K2 lenses. These are very suitable for eccentric cones. Also, the lenses work like a fl uid chamber in front of the cornea, therefore being good option for severe dry eye, Steven’s Johnson syndrome, corneal acid burn, irregular cornea etc.

In MSD lenses, comfort is high, no problem in dust, material is RGP (Boston XO2 with over Dk/t=120). This means that the lenses have long life and they correct lot many optical irregularities of corneal surface. Patients get exceptionally good vision, high oxygen availability, moisture (non-dry) and have no compromise with end of the day comfort.

Scleral lenses can be tried where Rose-K or MSD are also unsuitable. These lenses vault over the cornea to rest on sclera, way beyond the limbus. Cost of scleral lenses is prohibitive (as of now).

More aggressive and invasive procedures are available beyond scleral lenses.

Rose K


A new treatment for keratoconus is corneal inserts. Intacs corneal rings had previously been FDA approved for low amounts of myopia but received FDA approval in August 2004 to be correct or reduce nearsightedness and astigmatism in keratoconus patients who can no longer obtain functional vision with contact lenses or eyeglasses. The procedure involves placing the inserts with the corneal stroma in the periphery of the cornea. The result is a fl atter cornea and clearer vision.

Studies show that Intacs generally improve a patient’s best-corrected vision. Intacs are removable and exchangeable and the procedure takes only about 10 minutes. In fact, Intacs can allow a patient with keratoconus to defer or even avoid a corneal transplant. If necessary, Intacs do not preclude having a corneal transplant later if necessary. Potential risks that a patient with keratoconus must consider are infection, glare, halos, and foreign body sensation. A patient already experiences many of these risks with keratoconus prior to any treatment, but it is important to evaluate if this choice is feasible in the particular eye.

Intacs can be combined with C3-R (Corneal Collagen Crosslinking with Ribofl avin) treatment to provide a combined effect and provide greater stability than one treatment alone.

The fi nal method for treatment of keratoconus may be a cornea transplant, also called a penetrating keratoplasty. A donor cornea will replace the thinning cornea and can often provide stable vision. Even after a transplant, a patient will most likely need spectacles or contact lenses for clear vision. “Post Graft Rose K” and “Irregular Cornea Rose K” are specialty lenses that are created for specifi c needs at this stage.

In India, where to get Rose K and MSD lenses fi tted:

The author has now re-fi tted several keratoconus patients with RGP lenses. Almost half of these "regular RGP"

patients were refi tted with "Rose k lens." results are encouraging:

-Several best corrected (with regular RGP) 6/60 eyes improved to 6/18p or better, 6/12p improved to 6/9 or better.

Other major advantages are

- Apical staining disappeared

- Comfort and stability was markedly better. 95% patients have full day wear.

- Early to moderate keratoconus gets upto 6/6 vision

- Works well with all levels of cone. Early to advanced. The steepest BC that I have fi tted so far is 4.50mm (This is equivalent to 83D K reading and that too irregular).

Being an optometrist, we are also giving a service of patients. Those patients who have issues with dust, comfort, displacement of lenses or poor vision with regular RGP or Rose K2 lenses, a good option is MSD. The author has fi tted many patients with MSD (Mini Scleral Design) and has found success in getting crisp vision, good corneal health, no problem in dust and full day comfortable vision even in old “grief cases” of previous types of lenses.

With advancing technology, newer treatments of keratoconus are likely to provide still better vision and perhaps even cure keratoconus permanently.

Author Correspondance Rajesh Wadhwa

M.Optom.B.Ophth.Tech Hons.(AIIMS),

B.Sc.Hons. (DU),Fellow of International Assoc. of Contact lens Educators

(Australia)E-mail: [email protected]


A Decade of Optometric Profession in NepalSubodh Gnyawali, OD, MPH


Primary eye care has to be a part of primary health care system of a country. Integration of eye care into general health care system is essential to bridge the gap between community and eye care service providers. In the context where NGO’s and INGO’s have been the major eye care service providers since the last two decades, the concept of integration and thus the provision of comprehensive health services to the general public seems to go offhand. The government run HP/SHP rarely have basic eye health facilities. Neither are the in-charges form these facilities trained enough to identify and treat common eye diseases prevalent in the community. The development of optometry education in Nepal was an attempt to integrate primary eye care with primary health care of the country. The Apex Body formed for eye health has not been well functional since its establishment in 1999. Till date Nepal does not have a National Eye Care Policy. Although the human resource development in case of optometrists is in accordance to the National Plan of Action for Eye Care Services in Nepal (Strategic plan 2002-2019), “creating eye care unit at district hospital with optometrists” has remained just in document.Though designed for providing primary eye health services optometrists are capable of giving secondary and tertiary level services in certain fi elds of ophthalmology. The country has made ample investment in the education of the optometrists but has not opened up positions anywhere in the national health care delivery system for them to work. As a result the professionals are bound to leave the country for better job security and future endeavor. Once left, coming back for the sake of uplifting their profession or working for their own country remains unsecure for themselves in a world where better opportunities exist for those professionals who have acquired higher degrees from better institutions. Those left within the country are also confi ned to the major cities. This would not serve the purpose of “Vision 2020: The Right to Sight”. The university has just been a power house to produce these professionals; no effort has been made by the concerned authority in a decade to help establish this profession as a

respected one since the fi rst batch of optometry students graduated in 2001. The education above that, comes to a dead end with just a bachelor degree; need to go out of the country for further education diverts the national economy. The health care policy has remained dumb in utilizing this cadre of eye health human resource as a step towards meeting the greater goal of Vision 2020 which was the original idea behind the commencement of optometry education in Nepal.Optometrists themselves on the other hand are looking for a runway where they can have a safer landing. Association once formed has always gone through a state of turmoil just as the Nepali politics. The generation of running fund always gave “for what?” question in the minds of the members. Registration to World Council of Optometry and its renewal never gave fruitful results; but only added economic burden to the already fragile fund of the association. In a way it can be said that the association was not able to utilize the registration for its benefi t. The registration within the government system also has been challenging for the association. Lack of professionals who can volunteer their time for these clumsy processes has threatened the associations’ existence not only in the international community but also within the country. Insuffi cient inputs from the members and lack of motives to the executive committee has led the association non functional.Optometrists produced in this part of the developing world however have fl uttered their wings to different corners of the world. The quality of education they receive from the university is of the international standard. Several PhD holders are waiting to return provided better opportunities are available within Nepal. Credit however goes to the professionals themselves who have been successful in enrolling themselves in abroad universities for further education as no encouraging environment is seen within the educational and health delivery system of the country. Some optometrists are practicing their profession in different other countries for better economic opportunities been available there.


The optometric profession in Nepal unlike in other developed countries has a very short history. However the pace of shift in knowledge and technology is much faster than it used to be a while ago. Optometrists in the developed countries are much forward in managing the eye health problems of their people. The level of research they do are of much advanced kind and the development in technology they have achieved is a result of their hard working. It is time for the Nepalese optometrists to fi ght for a position within the health delivery system of the country as humble advocacies in the past failed. Tragedy lies in the fact that the visionary leaders who were behind the starting of optometric education in Nepal are reluctant

to help develop this profession. There are evidences of undue advantages been taken by different authorities in the name of optometry education in Nepal. Optometrists are expected just to be assistants of ophthalmologists and optometry has never been realized as an independent discipline. Anyway, this is not the time to blame any others but to come forward hand in hand in the spirit of professional solidarity and work for the betterment of the profession.

Author Correspondance Subodh Gnyawali, OD, MPH

Program Coordinator, BP Eye FoundationE-mail : [email protected]

Genaral Instruction on spectacles wears and care maintenance

Dr. Sanjeev Bhattarai, M. Optom, O.D, Consultant Optometrist, BPKLCOS• Please check up your eyes and vision regularly as early as 6 months to 1 year interval of time.• Vision in both eyes should be 6/6 as normal visual acuity.• In case if your glasses are broken or lost, consult with your eye doctor, Ophthalmologist/Optometrist to confi rm

the spectacle power and axis.• Always consult with your eye doctor before changing your spectacles in any reasons or if any problem begins in

your eyes.• Clean your spectacles lenses and frames with thin clean piece and liquid provided by an optical shop.• Alternatively clean lenses daily with dish detergent and warm water. Dry with a soft tissue/ lens cleaning cloth.

You can also clean lenses with clean cotton bud dipped in shampoo/ soap water with gentle touch on it. Rinse the cleaned lenses in running fl ow of tap water.

• Do not let the spectacles frames and glasess to be scratched/ cracked/ pitted. If such happens, please change the spectacles.

• After buying spectacles, please see for the adjustment/ tilting/ nose pads of spectacles with proper fi tting and appearance. Request to the optician if any problem arises in fi tting/adjustment of glasses.

• Choose the nature of the lenses and frames after consultation with eye doctor. It may be glasses/ plastic/ tinted/ AR coated/ Photochromic/ High index/ Bifocal/ progressive/ Polaroid/ Scratch resistant/ hard coated/ mirror coated/ UV coated/ Sunglasses etc.

• It may take 1-2 weeks for eye and spectacle power adjustment after dispensing you with it. If it persists for more than 2 weeks, consult with your eye doctor.

• Your spectacle lens power and contact lens power may not match with each other,. So, for proper prescription of each, consultation is necessary.

• Check up the eye power of your children before the age of 7 years. After that power should be monitored every 6months to 1 year.

• Near vision problems arises after the age of 40 yrs, so, glasses should be used for near works.• Minimum change in spectacle power up to 0.250D plus or minus, spherical or cylinder can be negligible your are

comfortable with your glasses.• In cases with sudden headache/ eye ache/ tearing/ Diplopia/ eyestrain/ discomfort/ blurring, consult with your

doctor and check up your refractive power and Oculomotor imbalance.



Prescribing Pediatric Refractive ErrorsNabin Paudel, B. Optom

American Academy of Optometry (AOA) recommends routine eye examination of children beginning from the age of 6 months. Special knowledge and expertise is required to diagnose and manage visual disorders in this particular population. Commonest childhood eye and visual problems are caused or complicated by the presence of refractive errors. Early detection and appropriate management of refractive error helps a child to achieve optimal acuity, binocularity and also plays an important role in his/her overall development.

Clinicians who frequently encounter this population at their clinics should be fully aware of the impact of treatment on any pediatric ocular disorders. Inappropriate refractive error prescription may hamper the child’s optical and neural development, consequence of which, he may have to suffer life-long. So, clinicians who frequently evaluate this population should take prescription of pediatric refractive errors a serious responsibility. Knowledge of the normal developmental process of optical components human visual system is of utmost important before prescription of refractive errors. Most commonly, the infant’s eyes are normally hyperopic, i.e. the light rays are slightly out of focus (they meet beyond the retina). With growth, radius of curvature of cornea and lens both increase and simultaneously the axial length so that the plane of focus (retina) coincides with the optical focus, leading to emmetropia. This process of reduction of refractive error with age is called emmetropization and this process is almost completed by the age of 6-8 years. The correction of normal amount of refractive error during this period is unnecessary. This article is intended to help clinicians as a reference while prescribing refractive errors in children.

Certain types and amounts of refractive errors are normal and transient in infant eyes. Prescription should be considered if the refractive error is stable and abnormally high. Signifi cant refractive errors should be monitored at least every 3 months during the fi rst year of life. Range of values of refractive errors present in infant and toddlers are given by a lot of researchers. By the age of 12 months, infants average no more than 2.00D of hyperopia (Banks and Ingram).

Normal values of refractive errors in Infants/Toddlers and preschool children are given below:

Infants/Toddlers (0-2 years)

Hyperopia Astigmatism Anisometropia

+2.00DS 2.00DC 1-3DPreschoolers (3-5 years)

+1.00DS 1.25DC < 3D

School age Emmetropia

Guidelines for prescription of refractive errors in children has been given by various professional organizations (AAO preferred practice patterns, AOA Optometric clinical practice guidelines), but gold standard criteria has not yet been created. According to various surveys on prescribing patterns of refractive errors in children among various eye care professionals, optometrists have been found to be more conscious in these matters. They have been prescribing refractive errors earlier and even of lower magnitude. In this article outlines the most commonly accepted guidelines among optometrists. Before that it is also equally important to have knowledge of the amblyopiogenic magnitudes of refractive errors.

Hyperopia Myopia Astigmatism

Isohyperopia: > 3.00DAnisohyperopia: > 1.00D

Isomyopia: > 8.00DSAnisomyopia:> 3.00DS

Isoastigmatism: >2.50DCAnisoastigmatism: >1.50DC

Above are the most commonly accepted magnitudes of refractive errors among optometrists worldwide; however some magnitudes, especially for hyperopia may vary.General guidelines for prescribing refractive errors in children are summarized in the table below:

The decision for prescribing refractive errors in school age children depends upon symptoms, binocularity and acuity status of the children. Even as low as ±0.50DS can be prescribed and much higher upto +2.00 - +3.00 can be avoided. This depends upon clinical judgment of a skilled clinician.


In conclusion, prescribing refractive errors in children is a challenging job for optometrists. Following proper guidelines and critically analyzing every case will be benefi cial for the children in comfort, visual development; on the other hand can be a reason for self satisfaction for the clinician as well.

References:

1. Marsh-Tootle WL. Infants, Toddlers, and Children. In: Borish’ Clinical Refraction. Benjamin WJ (ed). Philadelphia: WB Saunders 1998.

2. Carmen Barnhardt, Taming the Beast: Examining and Managing Young Children. COPE #25467, Southern California College of Optometry.

3. Ciner EB. Examination Procedures for Infants and Young Children. Journal of optometric vision development. 1998; 27: 54-67.

4. Scheiman MM, Amos CS, Ciner EB, Marsh-Tootle WM, Moore BM, Rouse MW. Pediatric eye and vision examination. Optometric Clinical Practice Guideline. St. Louis: American Optometric Association; 2002.

(The author is a consultant optometrist at B.P.Koirala Lions Center for Ophthalmic Studies and Sudristi Eye Clinic, Kathmandu and takes special interest on pediatric visual development.)

Non Strabismic and non symptomaticInfants/Toddlers

Hyperopia Astigmatism Anisometropia Myopia

≥ +3.50DS and stable

≥ 2.00DC( stable)Monitor 6 monthly

≥ 3.00D and stable (may consider partial correction)

≥-5.00DS and stable

Preschoolers ≥ +2.50 >1.25DC >1.00DS >-3.00DS

Strabismics/AmblyopesInfants/toddlers/preschoolers

Esotropia:Full cycloplegic correctionExotropia: Minimize correction

Goal is to achieve clear retinal image, in order to prevent meridional amblyopia.

Full correction Esotropia: Minimize correctionExotropia: Full correction

Author CorrespondenceNabin Paudel

OptometristBP Koirala Lions Center for Ophthalmic Studies

Maharajgunj KathmanduE-mail:[email protected]


Optometry Ethics and Practice Management PearlsHimal Kandel, Final Year, B.Optometry

Ethical principles and values are the foundation of professional integrity. Optometry ethics means how we ought to act in every aspect of life as an optometrist. After getting an optometrist’s degree; becoming a member of the optometry profession, it implies acceptance of a set of standards of professional conduct both in personal commitment and in actual practice. Optometrists are in a unique situation as health care professionals, in that we profi t from the sale of a product that we prescribe, and hence we come across many ethical dilemmas. Thus, Knowing basic concepts is very much essential for an Optometrist.

Distinctive expertise comprises of both theoretical knowledge and skills necessary to apply that knowledge into practice. Hence, the individual optometrist must master optometry to a suffi cient degree to be able to apply it correctly routinely independently. It is important to consider that decisions made by him in the fi eld of expertise will be taken as authoritative by people of other professions. Professions depend upon public trust. To safeguard the trust, professional groups and associations develop code of ethics that describe the ethical relationship that should exist between the caregiver and the society, the optometrist and the professional colleagues and, most importantly, the optometrist and the patients. Code of ethics and standard of conduct, and the optometric oath are the starting point for examining the ethics of the optometric profession.

Since optometry is a health profession not merely commercial, benefi ciary of professional services is suggested to be referred as ‘patient’ rather than ‘client’. Health of the eye and good vision for the patient are the central/core values for optometrists along with obligations regarding patient’s general health and even the patient’s life. Like in other health care professions, Hippocratic Oath including the primacy of the patient’s welfare, the duty to avoid causing harm and the preservation of confi dentiality is a must for optometrists to follow. In Health (and hence in optometry), a set of ethical principles includes benefi cence (striving to do best for every patients), non-malefi cence (no harm), autonomy, justice(fair to all), truth

telling, avoidance of deception, respect for confi dentiality, protection of vulnerable, collegiality (support of colleagues and fellow practioners / professionals) and professional competence. The ‘golden rule’ of treating others as we wish to be treated should be kept in mind.

Good communication is a cornerstone of good patient care. An optometrist should provide to the patient suffi cient information in order to obtain an informed consent from the patient. In the past and even these days, controlled communication of diagnostic and prognostic information for the power of placebo maintaining therapeutic trust is practised. Today, truth telling and informed consent, rather than deceptive reassurance, are the standard for good clinical communications as respecting patient’s autonomy. Moreover, today’s patients are more concerned about maintaining their own health and well educated about health related issues. In the process of informed consent, patient should be told about diagnosis or problem to be addressed, risks and benefi ts of the proposed intervention, the alternatives to the proposed intervention with their risks and benefi ts. Regarding children, when the optometrist, child and the adult decision maker all interpret the child’s best interest in the same way, the decision-making process for examination and treatment is straight forward. But, for example, if the child accepts a recommended cause of action but the adult decision maker rejects it, resolution may be diffi cult. Communicating carefully the options for action – including no action, listing them in order of their benefi t to their patient, and to let the child and the decision maker choose from among them is a widely used logical approach.

As mentioned in the standards of conduct by American Optometric Association prime objective of optometrist is the service it can render to community; monetary considerations should be the subordinate factor. Charges for materials should be clearly separated from the professional fees. When a medically indigent patient (who can’t fi nancially afford for the optometric examinations or for treatment) comes to the optometrist’s offi ce with a problem within the optometrist’s expertise, the practioners should ensure at a minimum that no additional harm will



come to the patient if he or she refuses to provide treatment. It must be remembered that such patients should not be asked to participate in research or training activities for which paying patients are not also recruited. For paying and non-paying patients alike – as a point of ethics and good practice management – optometrists must make certain that their offi ces are friendly and openly welcoming to everyone. For example, it is always inappropriate for the receptionist to discuss a patient’s bill or fi nancial situation within earshots of others in the waiting area or exam rooms. Irrespective of their ability to pay, patients tend to judge the quality of their care on the basis of how they are treated while in the offi ce, and not on the results of any intervention.

Beside the ideal relationship with the patients, it is professional obligations for optometrists to have ideal relationship between co-professionals, the larger community (all eye care professionals) and other related professionals. Screening is a good practice building activity. It is important for community relations; get your name in the papers. In the long run, successful screenings (often free of cost) draw in new patients. In fact it is considered one of the principles of practice management. Moreover, community-based screening programs may create awareness of optometry’s benefi ts and bring new patients to the optometrists.

In an optometry practice, it is important for other staff to know the limits of their knowledge and authority, and to know when to turn to the optometrist with questions. Similarly, when a practice has more than an optometrist, whether in a small offi ce or in a larger clinic, it is likely that more than one will see the same patients over time. The optometrist who treats a colleague’s patient may need to reassure the patient that his or her original optometrist will still be in charge of the case. In such conditions, it is essential for everyone to be sure that their records are complete and legible so that colleagues can readily establish an unfamiliar patient’s diagnostic and treatment history.

Ethics in health care is becoming more complex and optometry’s expanding scope of practice makes the ethical issues for optometrists more challenging. An optometrist should strive to keep current with every modern development in the profession. Many ethical issues are affected by legal standards, and hence it is important for optometrists to know law relevant to their practice. Whenever optometrists face unfamiliar ethical questions or unexpected confl icts between principles and practice standards, systematic methods of ethical reasoning and decision making are essential.

References:

1. An optometrist’s guide to clinical ethics. Bailey RN and Heitman E. American Optometric Association, St Louis Missouri Available from http://www.aoa.org/documents/book.pdf

2. Ethics in Optometric Practice- the Obligations that Defi ne a Profession doi: 10.3921/ joptom.2008.5 Available from: http://dx.doi.org/10.3921/joptom. 2008.5

3. Ethics of optometry. Pierscionek BK. Law & Ethics for the Eye Care Professional. Butterworth Heinemann Elsevier, Edinburgh, London, 2008. Available from: http://findarticles.com/p/articles/mi_qa3921/is_200209/ai_n9142081/

4. Chadwick J, Mann WN. Hippocratic writings. Penguin Books, London, 1950.

5. Beauchamp TL, Childress JF. Principles of Biomedical Ethics. 5th edn New York: Oxford University Press; 2001.

Author CorrespondenceHimal Kandel




Kids’ Vision is Falling Through the CracksMichele Marshall, O.D., F.C.O.V.D.

A study released recently by the Centers for Disease Control and Prevention (CDC) fi nds that millions of children do not receive the vision evaluations recommended by top medical organizations, placing them at greater risk for permanent vision loss, as well as physical and emotional diffi culties. The study, published as the lead article in the May 6, 2005 edition of CDC’s Morbidity and Mortality Weekly Report, says that only 1 in 3 children received a vision screening or eye exam before entering kindergarten. Other studies have shown that as few as 1 in 7 to 1 in 10 children actually receive vision and eye health examinations by the time they are 6 years old. This is concerning, since it is felt that more than 80% of what is learned as a child enters school comes through the eyes. These undetected vision and eye health problems are potentially devastating to the learning process.

The American Optometric Association reports that vision and eye health problems in children are relatively common:• 1 in 10 children is at risk from undiagnosed vision

problems• 1 in 30 children will be affected by amblyopia – often

referred to as lazy eye – a leading cause of vision loss in people younger than 45 years

• 1 in 25 will develop strabismus – more commonly known as crossed-eyes – a risk factor for amblyopia

• 1 in 33 will show signifi cant refractive error such as near-sightedness, far-sightedness and astigmatism

• 1 in 100 will exhibit evidence of eye disease • 1 in 20,000 children have retinoblastoma (intraocular

cancer) the seventh most common pediatric cancer

The report also states that approximately 1.8 million children under the age of 18 (2.5%) are blind or have some form of visual impairment. Many cases of visual impairment could be eliminated simply through more timely diagnosis and treatment.

According to the American Academy of Pediatrics, all children should receive a vision screening before entering school, and the American Academy of Ophthalmology recommends either a vision screening or an eye exam in the preschool years. The American Optometric Association recommends that all children should receive a comprehensive eye and vision examination assessing and treating any defi ciencies in ocular health, visual acuity, refractive status, oculomotility and binocular vision prior to entering school, fi rst at age 6 months and then again at age 3. This is followed by another examination before fi rst grade. The child should then continue to have comprehensive eye and vision examinations every 1 or 2 years thereafter.

Every parent needs to have their children’s eyes checked early and often. There is no more precious gift than the gift of good vision and eyesight.

For further information on children’s vision, see the following websites:www.aoa.orgwww.infantsee.orgwww.seetolearn.com


Author CorrespondenceMichele Marshall

Swan Vision Center607 Main St East

Swan river, Manitoba CanadaE-mail: [email protected]


Contact lens PractionersDinesh Kaphle, B.Optom

Do you know?

What is contact lens (CL)? How are they made; spin-casting, lathe turned, molding? Which materials are used; PMMA (polymethylmethacrylate), polymers, CAB (cellulose acetate butyrate), fl uro-silicon? Who manufacture them; Vistakon/ Johnson & Johnson, CIBA vision, Bausch & Lomb, Copper vision, Purecon, Menicon or others? What do you mean by OD (overall diameter), OZ (optic zone), BC (base curve), CT (centre thickness) and BVP (back vertex power)?

What are the types of lenses? Soft, hard, RGP (rigid gas permeable)? Refractive, Cosmetic, Therapeutic? Scleral, Corneal, Intracorneal? Spherical, Toric? Is there any difference in terms of wearing period; Daily wear, extended wear or continuous wear? Can you tell which CL are used in entertainment industry?

What are the advantages and disadvantages of CL? What is the effect in wet weather, steam and sports? How much will be the Field of view (FoV) as compared to spectacles?

What are indications and contraindications? How they work in keratoconous, aniridia, dyscoria and anisometropia? What about for color blind people? Is there any role of red tinted ‘x-chrom’ contact lens? Do contact lenses have any role in bullous keratopathy, corneal ulcers, erosions, keratitis dry eyes, descemetocele, mooren’s ulcer and neurotrophic keratoconjunctivitis?

Do you have any idea how you do you take care of them? What is the function of MPS (multipurpose solution), Saline, H2O2 (hydrogen peroxide) BKC (banzyalkonoium chloride), Thimerosol? What about insertion, removal and storage methods?

What are the complications and the remedies related to CL? Can you tell how following complications happen; Corneal infi ltration, corneal ulcers, contact

lens red eye (CLARE) Giant Papillary Conjunctivitis? Is contact dermatitis, superior limbic keratitis (SLK), corneal neovascularization also related to CL wear? Which organisms are involved; pseudomonas aeruginosa, staphylococcus aureus or epidermidis, streptococcus sp.

Are you updating yourselves what’s new in Orthokeratology, piggy backing CL and Multifocal CL?

Are you familiar with these terms; permeability, permissibility, ionic content, water content of CL?

These are some of the general questions for contact lens practioner. A person practicing contact lenses must have at least knowledge of these things. If anyone practices contact lenses without having much knowledge theoretically and practically, it will be a disaster not only for the Contact lenses profession but also for the patient, who have trust on you.

What is needed for contact lens practice?

Contact lens Specialist Contact lens specialist is that who earned adequate

knowledge about contact lens through academic degree or extensive training program. Optometrists, ophthalmologists, special trained ophthalmic assistants/opticians can be the contact lens practitioner. Optometrists are the right practitioners of contact lenses in context of Nepal now.

Contact Lens Equipments To be a contact lens specialist you need to have certain

equipments before you start the practice. Some of them are; Keratometer. Corneal topographer is ideal. Refraction set. Auto refractor adds advantage. Contact lens trial set; soft, toric, RGP,

keratoconous Slit lamp bimicroscope Tears assessment tools



Tonometer, ophthalmoscope are plus point Retinal Camera, Specular microscope, visual

Field screener may be needed

Contact lens Stock After contact lens trial you cannot recommend any

contact lens or lens solution available in market. Lenses are like medicines for your body. If any complications happen you will be responsible. So, you need to have adequate lenses stock of some branded company.

Practice License You need to get the license of practitioner and the

practice centre from your local available health authority. Practicing without the license is illegal. The charges of the consultation and the cost of contact lenses and the solution are also to be regulated by the health authority.

Referral Centre Sometimes Contact lens practice may be the co-

management effort. You might need the opinion from other experts for further management. So referral centers should be available in feasible distance.

So please don’t take contact lenses as only fashion and business. They are much more than those.

References

www.wikipedia.com, www.thecontactlenspractice.co.uk

Author CorrespondenceDinesh Kaphle

OptometristNepal Medical College and Teaching Hospital

Jorpati KathmanduE-mail:[email protected]


Eye in Methanol IntoxicationSanjay Marasini, B. Optom

Methyl alcohol is consumed in our country for social, cultural and traditional implicatioins. Most of the well-off family drink industry prepared alcohol while others are limited to the home prepared alcohol which has greater chances of being contaminated with methanol. Fowlie DG emphasizes about the increased consumption of alcohol among physicians.1 Methyl alcohol is a colorless and odourless toxic alcohol. The accumulation of the toxic metabolites of the methanol; formaldehyde and formic acid are reported to account for the metabolic acidosis and cellular dysfunction. Major methanol poisoning affects the optic nerve and the central nervous system with a predilection for basal ganglia, resulting in symptoms of visual disturbances, blindness, drowsiness, seizures and coma.2 Without treatment, ingestion of 30 ml (0.5mg/kg body weight) of pure methanol usually results in death and as little as 4 ml can result in blindness.3

The severity of the visual abnormalities is directly correlated with the severity of the metabolic acidosis. The ocular fi ndings range from mild blurring of vision to double vision, photophobia and changes in colour perception. Some patients are reported to have constricted visual fi eld and occasionally total loss of vision. Characteristic visual fi ndings include pupillary dilation and loss of pupillary refl ex. Other diagnostic clues may include hyperemia of the optic disc, optic disc edema or disc pallor. Abdominal pain can be present and sometimes neurologic abnormalities including confusion, stupor, and coma are often present. The most severe neurologic dysfunctions are found in patients with the most severe metabolic acidosis.4 Although most patients will recover normal visual function, permanent impairment of vision has been observed in patients ranging from 11 to 18%.5, 6

A rare complication of methanol intoxication is putaminal necrosis, which presents with rigidity, tremor, masked faces, and monotonous speech.7

Retinal damage in methanol toxicity is believed to be due to the inhibition of retinal hexokinase by formaldehyde; an intermediate metabolite of methanol.8 After entering into the retinal circulation formic acid inhibits cytochrome oxidase in the retina. Then it impairs mitochondrial

function resulting into decrease in ATP production and fi nally leading to disruption of axoplasnic fl ow and swelling of axons in the optic disc and subsequently resulting into retinal nerve fi bre layer edema. This causes marked visual impairment.9 Bilateral ocular involvement is the most expected fi nding. The electrophysiological test in methanol poisoning shows the diminished a- and b-waveforms.10

High anion gap metabolic acidosis (blood pH 6.8 to 7.3) primarily as a result of formic acid accumulation is often present.5 As methanol metabolism proceeds, the serum bicarbonate falls concomitantly with a rise in anion gap and fall in serum osmolality. After the bulk of the methanol has been metabolized, little or no increase in serum osmolality will be present, whereas the serum anion gap can be strikingly increased and the serum bicarbonate markedly depressed.

The diagnosis of methanol poisoning is based on the positive history of methanol ingestion or methanol containing products. Furthermore investigations like serum methanol concentration, anion gap metabolic acidosis and an osmolal gap confi rms the diagnosis. Measurement of methanol in blood is important to confi rm the diagnosis of methanol intoxication and can be valuable in assessing the response to treatment. It has been emphasized that pupillary status provides the best prognostic information for both morbidity and mortality.11

The therapy of methanol poisoning is based on alkalinisation and ethanol administration. Ethanol competes with methanol for the enzyme alcohol dehydrogenase in the liver thereby inhibiting the accumulation of toxic metabolites of methanol in the body. The three primary goals of therapy include treatment of metabolic acidosis, inhibition of the methanol metabolism and enhanced elimination of the unmetabolized compound and existing toxic metabolites.12

Currently recommended management aims to delay methanol metabolism by using intravenous ethanol infusion, gastric lavage, alcohol dehydrogenase enzyme blockade by means of fomepizole, haemodialysis,



alkalinisation, high dose intravenous steroids and use of cofactors such as folic acid. 13,14 Folic acid enhances the metabolism of formic acid. Hemodialysis has been used to remove methanol and formate and to correct the metabolic acidosis.

The prognosis of visual recovery depends on the time of presentation after toxication, metabolic acidosis, pupillary involvement and the mode of treatment. Early presentation with a prompt treatment has a signifi cant role to preserve and to improve visual acuity.

References

1. Fowlie DG. The misuse of alcohol and other drugs by doctors: A UK report and one regions’s response. Alcohol & Alcoholism. 1999; 34(5): 666-71.

2. Koopmans RA, Li DKB, Paty DW. Basal ganglia lesions in methanol poisoning: MR appearance. J Comput Tomogr 1988;12:168–9.

3. Agency for Toxic Substances and Disease Registry, U.S. Department for Health and Human Services. Methanol Toxicity. American Family Physician. 1993;47(1):163-171.

4. Kraut JA, Kurtz I. In-Depth Review. Toxic Alcohol Ingestions: Clinical Features, Diagnosis, and Management. Clin J Am Soc Nephro.l 2008;3: 208–225.

5. Hovda KE, Hunderi OH, Tafjord AB, Dunlop O, Rudberg N, Jacobsen D: Methanol outbreak in Norway 2002–2004: Epidemiology, clinical features and prognostic signs. J InternMed. 2005;258: 181–190.

6. Paasma R, Hovda KE, Tikkerberi A, Jacobsen D: Methanolmass poisoning in Estonia: Outbreak in 154 patients. ClinToxicol. 2007;45: 152–157.

7. Barceloux DG, Bond GR, Krenzelok EP, Cooper H, Vale JA:American Academy of Clinical Toxicology practice guidelines on the treatment of methanol poisoning. J Toxicol ClinToxicol 2002;40: 415–446.

8. Martin-Amat G., Macmartin K. E., Hayreh S. S., and Tephly T.R.Methanol poisoning: Ocular toxicity produced by formate. Toxicol and Appl. Pharmacol. 1978;45:201-208.

9. Kraut J A., Kurtz I. Toxic Alcohol Ingestions: Clinical Features, Diagnosis, and Management. Clin J Am Soc Nephrol. 2008;3:208–225.

10. McKellar MJ, Hidajat RR, Elder MJ. Acute ocular methanol toxicity: clinical and electrophysiological features. Aust N Z J Ophthalmol. 1997 Aug;25(3):225-30.

11. Sullivan- Mee M, Solis K J. Methanol-induced vision loss. J Am Optom Assoc. 1998 Jan;69(1):57-65.

12. Ravichandran RR, Dudani RA, Almeida AF, Chawla KP, Acharya VN. Methyl alcohol poisoning. (Experience of an outbreak in Bombay). J Postgrad Med. 1984;30:69-74.

13. E.S. Lin, T. Buckley, E. Li, K.N. Lai and T.E. Oh. Case Reports: A Case of Severe Methanol Intoxication. Journal of the Hong Kong Medical Association. 1989;41:8.

14. Gonda A., Gault H., Churchill D., Hollomby D. Haemodialysis for methanol intoxication. Am J. Med. 1978,64:749-758.

Author correspondenceSanjay Marasini

OptometristKathmandu University Teaching Hospital

Dhulikhel HospitalE-mail- [email protected]


Behavioral OptometrySuraj Upadhyaya, Final Year, B. Optometry


It has been said that the most complex thing in the known Universe is the brain, and the most complex thing that the brain does is vision. 87% of all learning is done through vision, 6% through hearing and 7% from the rest of the body. Vision is therefore the dominant process in the human species. Fortunately, it is also the most accessible to change through the use of behavioral vision care with lenses and vision training.

Behavioral optometry is a system of eye care that emphasizes visual training as a way to improve the way a patient uses his or her eyes. Rather than simply prescribe lenses to compensate for eyesight weaknesses, it attempt to train the patient to see better across a range of different circumstances. Behavioral optometry defi nes vision as “the ability to derive meaning and direct action through light”. It explores and examines how the visual input at the eye is dealt with in the brain and how it integrates with other brain processes e.g. hearing, movement, touch etc.

Behavioral optometry (also known as "functional optometry") is an expanded area of optometric practice that claims to use a "holistic" approach to the treatment of vision and vision information processing problems. The practice of behavioral optometry incorporates various vision therapy methods and has been characterized as a complementary alternative medicine practice.

Behavioral branch of optometry generally deals with problems like dyslexia, dyspraxia, ADD and ADHD (Attention Defi cit Disorder and Attention Defi cit Hyperactivity Disorder), headache, double vision, fatigue, amblyopia, traumatic brain injuries, poor concentration, poor reading performance, children with behavioral problems etc. The main them of behavioral science in vision related problems is to improve visual skills like tracking, tracing, fi xation, binocular vision, stereopsis, fi eld of vision, fi eld of perception, convergence etc .

Vision disorders are the 4th most common disability in the US and leading cause of disabling conditions in childhood according to a study recently reported in Optometry and Visual Science.

Behavioral optometry is a related area of non-strabismus vision therapy It generally involves intense therapy that requires at least a weekly visit with eye exercises at home. In some cases it can improve vision beyond that which eyeglasses alone can do.

References

1. THE FORENSIC EXAMINER Spring 2007 A Behavioral Optometry/Vision Science Perspective on. The Horizontal Gaze Nystagmus Exam for DUI Enforcement By Eugene R. Bertolli, J. Forkiotis;Dominic R. Pannone, and Hazel Dawkins

2. Keith Holland, The science of behavioural optometry by Optometry today 2002 March 8.

3. Dr. Raj Patel, Optometry Tools, Journal of Behavioral Optometry

4. Birnbaum MH. "Behavioral optometry: a historical perspective." J Am Optom Assoc 1994 Apr;65(4):255-64. PMID 8014367

5. Jennings (2000). "Behavioural optometry – a critical review.". Optom. Pract. 1 (67).

6. "A.M. Skeffi ngton, O.D.: The Father of Behavioral Optometry." Visionaries (Reprinted from January-December 1991 Issues of Review of Optometry) Copyright 1999 Review of Optometry. Accessed September 19, 2006.

7. Oliver Sacks (June 19, 2006). "A Neurologist's Notebook: "Stereo Sue"". The New Yorker. pp

Author CorrespondenceSuraj Upadhyaya




Visual Agnosia: “To See But not to See” Safal Khanal, Second Year, B. Optometry


Agnosia

Agnosia is a perceptual disorder in which sensation is preserved but the ability to recognize a stimulus or know its meaning is lost. Agnosia means “without knowledge”. Patients with agnosia cannot understand or recognize what they see, hear or feel. Agnosia results from lesions that disconnect and isolate visual, auditory and somatosensory input from higher level processing.

Visual Agnosia

Visual agnosia is the inability of the brain to make sense of or make use of some part of otherwise normal visual stimulus and is typifi ed by the inability to recognize familiar objects or faces. This is distinct from blindness which is a lack of sensory input to the brain due to damage

Type Defi cit Most probable site of lesionsAgnosia for form and patternObject agnosia Naming, understanding of purpose,

recognition of real objectsArea 18,20,21 on left and corpus callosum

Agnosia for drawings Recognition of drawn objects Area 18,20,21 on right Prosopagnosia Recognition of faces Area 20,21 BilaterallyAgnosia for colorColor agnosia Association of colors with objects Area 18 on rightColor anomia Naming colors Speech zone or connection from

Area 18, 37Achromatopsia Distinguishing colors Area 18, 37Agnosia for depth and movementVisual spatial agnosia Stereoscopic vision Area 18, 37 on rightMovement agnosia Discerning movement of object Bilateral medial temporal area

to the eye, optic nerve or primary visual systems in the brain such as the optic radiations or primary visual cortex.

Visual agnosia is a defi cit in object recognition confi ned to the visual modality, despite intact elementary visual processes and which is not due to problems in language, memory or intellectual decline. It is the most common and best understood form of agnosia.

The specifi c symptoms can vary depending on the cause of the agnosia. Some sufferers are unable to copy drawings but are able to manipulate objects with good dexterity. Commonly, patients can describe objects in their visual fi eld in great detail, including such aspects as color, texture and shape but are unable to recognize them. Similarly, patients can often describe familiar objects from memory despite their visual problems.

Appreciative visual agnosia

Apperceptive visual agnosia is characterized by an intact visual ability on a basic sensory level, but a defect in early stage visual processing prevents a correct percept of the stimulus being formed. The patient is unable to access the structure or spatial properties of a visual stimulus and the object is not seen as a whole or in a meaningful way. Stroke, anoxia and carbon monoxide poisoning are common causes and it is often associated with diffuse, posterior lesions.

Patients fail tests such as visual matching, discriminating shapes, comparing similar fi gures and copying drawings.

Associative visual agnosia

In associative visual agnosia, primary sensory and early visual processing systems are preserved. The patient can perceive objects presented visually but cannot interpret, understand or assign meaning to the object, face or word. Associative visual agnosia is usually the result of bilateral damage to the inferior temporo-occipital junction and


subjacent white matter. The cause is most often infarction of the posterior cerebral artery bilaterally. Other causes include tumour, haemorrhage and demyelination.

Subtypes

1. Visual object agnosia

Patients are able to copy objects and pictures, often with great accuracy, but do not recognize the objects or understand what they have drawn. A patient with visual object agnosia is unable to name or recognize a kangaroo. The same patient has no diffi culty describing characteristics of kangaroo as “it’s found in Australia and it jumps”

2. Simultanagnosia

Simultanagnosia is characterized by an inability to perceive more than one aspect of a visual stimulus and to integrate visual detail into a coherent whole. For example,

if a patient with Simultanagnosia is asked to name a picture of spectacles, they may respond “there is a circle, another circle, it is joined by a cross piece – it must be a bicycle!”

3. Prosopagnosia

Prosopagnosia is a disorder of face recognition. Patients can identify facial parts; recognize a face as a face but with no recognition of the person. In severe cases, patients cannot recognize their own face.

4. Color agnosia

Loss of colour knowledge. Patients fi nd it diffi cult to colour black and white drawings of objects. For example, they may colour an apple blue.

5. Pure alexia

Pure alexia is a perceptual disorder causing impairment in reading words and letters. The patient can write to dictation but is unable to read back what has been written.

6. Mirror agnosia

Mirror agnosia is the inability to differentiate between the real and refl ected objects

Treatment and recovery

In the early stages of recovery, lack of awareness of the defi cit, anosognosia, may lead to therapeutic resistance. Partial recovery is more likely in traumatic and vascular lesions and less likely in anoxic brain damage. Many case reports have shown improvement following intensive rehabilitation. Principles of treatment are restitution, repetitive training of impaired function, and compensation, with utilization of spared function to compensate.

Some patients can be helped by attending rehabilitation to make them aware of their defi ciencies and to help them come up with a strategy to compensate. Clinical trials have shown that this can be a very effective way to counteract the effects of lesions leading to visual recognition disorders, although responses are often slow and require a great deal of time and effort to execute even after hours of training/practice.

References:

1. Goldstein E. Bruce. Sensation and perception 5th edition

2. Kandel E.R, Schwartz J.H, Jessell T.M. Essentials of neural science and behavior

3. Schwartz S.H. Visual Perception: A clinical orientation, 3rd edition

4. Palmer C.N. An examination of visual agnosia. Stephen F. Austin State University

5. Zihl J, Kennand. Disorders of higher visual functions. In Neurological disorders, course and treatment.1996

6. Farah MJ.Visual agnosia.MIT press, Cambridge, MA 1990

7. Visual Agnosia- A disorder of the ventral stream. Department of applied health sciences, University of Waterloo

Author CorrespondenceSafal Khanal

Second Year B.Optometry StudentMaharajgunj Medical Campus



Visual Status for DrivingSudan Puri, Second Year, B. Optometry


The rampant nature of road accidents in recent times has been a source of worry for the Government, stallholders in the transport industry and all concerned. It is particularly worrying because a lot of innocent lives have been lost through these otherwise preventable accidents. The various causes of road traffi c accidents among which are excessive speed, inattention or lack of judgment of drivers, carelessness, improper overtaking, inexperience, intoxication, recklessness and mechanical defects. Others factors are overloading, defective and dazzling lights, road surface defects, obstruction, level crossing, boarding or alighting from vehicles and uncontrolled animals. Ostensibly other contributing causes are lack of proper enforcement of road safety regulation, corruption, use of mobile phones while driving, and not wearing seat belts. While all the above is true, and undisputedly dynamic in causing road accidents, one major phenomenon that has not been diagnosed and still remains unperceived is the visual status or simply how well a driver can resolve and see discrete objects on and off the road comfortably.

Vision; our ability to see details clearly plays a vital role in driving and many other occupations where good and effi cient visual functioning of the individual is essential. Passengers’ lives are entrusted to the hands of drivers, but without good vision the driver is in danger of causing a tragic accident. The ability of a driver to see the features of objects s/he looks at, such as colour, shape, size, details, depth, and contrast if defi cient or below the expected standard reduce safety and increase the risk of crashes. A driver’s visual acuity must at least be such that s/he has time to detect and react to obstacles, pedestrians, other vehicles and signs while moving at the maximum posted speed in daylight and in the night. Greater levels of visual acuity are required for some classes of vehicles to ensure public safety on today’s congested and high-speed roads. Road signs should be designed to be easily legible at a safe distance for all drivers who meet the minimum visual acuity standard. An adequate continuous fi eld of vision is important to safe driving. Any signifi cant scotoma or restriction in the binocular visual fi eld can make driving dangerous. If a visual fi eld defect is suspected (based on a medical condition, subjective report or confrontation

fi eld assessment), the patient should be referred to an ophthalmologist or optometrist for further testing.

To ensure that drivers, both commercial and private have the required vision to qualify for a drivers’ license, it is required to assess the occupational vision. Such an assessment should encompass more than the mere testing for required visual acuity. It should involve the effi cient and safe visual functioning of the individual within the driving environment, the demands these requirements place upon the driver, visual effi ciency and comfort. Since the act of driving increases the demand placed on the visual system including the brain, failure to apply the above criteria will result in visual shortcomings which have dire consequences.

Around 300 driving licenses are issued everyday by the Department of Transport Management Bagmati Zonal Offi ce, Ekantakuna1. To acquire a driving licence, the copy of a licence form needs to be fi lled in. A health check -up report is required to ascertain that the applicant’s eyes and ears function properly2. As at now, only static visual acuity of prospective drivers is measured, this is not adequate. Dynamic visual acuity is the most appropriate test to be conducted for drivers. Dynamic visual acuity tests vision when you are in motion and static visual acuity tests your vision when you are at rest. Visual fi elds, colour vision and binocular functions are left unchecked. A comprehensive visual examination will ensure that the driver whilst driving is able to read his speedometer, signs on the roadside, see objects in front of him, intermediate and distant correctly, perceive a potentially dangerous situation altogether and react appropriately. He should also be able to distinguish colour differences, perceive depth and judge distances whilst driving.

Though the drivers’ license application stipulates that qualifi ed specialists are permitted to conduct medical assessment of vision readiness of potential drivers2, this is not being enforced making the completion of the form a mere formality. It must be remarked that these tests involve complex techniques that require expertise to conduct them. Ineligible examiners will undermine the


fi nding and put the lives of a driver and passengers in jeopardy. Signifi cant refractive errors, glaucoma, cataract, binocular abnormalities and other retinal disorders are left undetected, to the detriment of the health of drivers and putting them at the risk of accidents.

Consider granting license to the following applicants; an undiagnosed advanced glaucomatous person who may see the required line of 6/9 or better on the visual acuity chart because his central vision is preserved but with drastically diminished peripheral vision preventing him from perceiving objects and cars approaching from his side view, a person with advanced cataract who may be seeing objects as double, a person with constricted visual fi eld and experiencing glare at night but squints to read the required line during the visual acuity test, a colour blind person who may not be able to distinguish the colours of traffi c lights, and an applicant with binocular abnormality who may feel a lot of discomfort and tiredness (asthenopia) after driving for two hours. Quite clearly the consequences are imaginable. Some drivers are also able to bribe their way through without even going through the necessary procedures before getting their licence. The fear of failing an eye examination must not be tolerated since Optometrist and Ophthalmologist are well vest in correcting refractive errors and administering the necessary ocular therapy to correct disorders detected. The police who normally scrutinize drivers‘ license must also ensure that drivers are in their prescribed spectacle correction whilst driving.

Cost implications are not tangible excuses as the burden one suffers after an accident and even bribes paid to avoid eye exams far exceeds charge for eye specialist. The World Health Organization also projects that by the year 2020 annual road fatalities will increase by 80%. 3

The relationship between poor vision among commercial vehicle drivers, barriers to treatment and road accidents must be investigated. Comprehensive medical assessment of visual requirement for drivers’ license must be performed by a qualifi ed Ophthalmologist or Optometrist within the right setting in order to reduce the number of road accidents throughout the country.

References

1. Department of Transport management – www.dotm.gov.np.

2. Motor Vehicles and Transportation Act 2049(1993) Section 47.

3. Paden M et al (eds) World report on road Traffi c injury Prevention, Geneva, WHO, 2004

Author CorrespondenceSudan Puri

Second Year B.Optometry StudentMaharajgunj Medical Campus



Documents

The Sight Vol -6 Issue 6