Multifocal Contact Lenses(1)

7/28/2019 Multifocal Contact Lenses(1)

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How to ccee withmltiocal contact leneCOuRsE COdE: C-15605 O/CL

dr Cameron Hon Bsc (Hon), Phd MCOptom

The prescribing o frst generation multiocal contact lenses a decade ago was

oten a rustrating process, yielding low success rates amongst patients. Even

today, many practitioners are reluctant to ft multiocal lenses despite signifcant

improvements in materials, designs and parameter ranges,1 which provide

better visual outcomes2 and more satisfed patients.1 This article reviews the

current status o multiocal contact lenses and guides practitioners on how

to reliably achieve high levels o success and satisaction amongst wearers.

In the UK, the presbyopic population

represents the largest growing, yet least

developed, segment o the contact lens

market.3 Contact lens options available

or presbyopes include multiocal contact

lenses, monovision, or a combination o

single vision distance contact lenses with

reading spectacles. In light o the potential

to both increase the number o patients

who can beneft rom contact lenses and to

generate additional revenue, it is interesting

to consider the lingering actors that prevent

practitioners rom tackling the presbyopic

challenge. For many practitioners, it

may be that a previous bad experience

limits their enthusiasm or multiocal

lenses. For others, it may be a ear o

ailure to achieve promised outcomes, or

an uncertainty regarding what to expect

over the short-, medium- and long-term.

Ever-increasingly, presbyopes enjoy better

health and increased vitality during the

middle years o lie. The range o activities

carried out and attitudes towards physical

appearance have changed substantially over

the past 20 years. These actors, along with

other social trends, are likely to make visualcorrection options that are uninhibiting

and burden-ree increasingly attractive.

Figre 1

Schematic to indicate the generic design principle

o a centre near multiocal contact lens

A huge disparity exists between the

common desire amongst presbyopes

or reduced spectacle dependence and

the actual use o contact lenses in this

population.4 As a result, manuacturers

have applied a range o optical principles

to produce dierent multiocal contact

lens corrections, which can be applied

to suit the individual eye or unctional

requirement, o the patient. Similarly,

contact lens materials have evolved to

improve oxygen transmission (eg, silicone

hydrogels), reduce wetting angles, and

resist deposition and dehydration, in

order to minimise the impact o dry eye.

The visual environment o the typical

presbyope has also evolved at a rapid

pace, with less emphasis on near work at

a relatively close distance (40cm or closer)

in down gaze and greater emphasis on

visual display units (VDU) and mobile

phones at a range o distances rom

40cm (and closer) to 80cm (and beyond).

There is a common view amongst

practitioners that correcting presbyopia

with monovision requires less chair time

and yields higher success rates comparedwith multiocal contact lenses.5 However,

over the past two years, practitioners

throughout the UK and Europe have begun

to show avour towards multiocal lenses.6

In the UK alone, this segment o the industry

is growing at a rate o approximately 5,000

new wearers per quarter.6 Despite these

new ftting behaviours there is still a long

way to go beore multiocal contact lenses

to correct presbyopia becomes the norm.

What are the principle o crrentmltiocal contact lene?

The latest generation o sot multiocal

contact lenses are based on the principle

o simultaneous vision whereby multiple

powers are placed within the pupil at the

same time. Thereore, light both rom the

distant and near portions o the lens is

ocused onto the retina simultaneously.

This description, however, tends to over-

complicate the reality, which is that

when a patient views a distant object

the image quality will be aected

by the area o relative positive power

(near zone). The reverse is true when

viewing near objects. Thus, or any given

simultaneous lens design, the amount to

which the image is aected depends on

a careul balance o the ollowing actors:

Relative size of the distance and near

optic zones

Blending, or non-blending, of the

distance/near zone junction

Rate of blending of the distance/near

zone junction

Relative position of the near optic zone(centre-near vs. centre-distance and/or

concentric design)


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emerging presbyopes. For many o these

individuals, contact lenses have been

the reractive correction o choice. They

are also ar more aware o contact lenses

and have ar more varied visual needs

than established presbyopes. Unlike

baby boomers, these individuals are more

likely to embrace technology eg, using the

Internet and mobile phones. Accordingly,

these individuals are more likely to be

motivated to preserve their unctional

visual ability as well as their appearance.

Historically many practitioners may

resist correcting presbyopia until as late

a stage as possible. However, the key to

multiocal contact lens success is tackling

the emerging presbyopic changes beore

becoming overtly maniest. The ideal time

is when patients report that their ability to

change ocus is reducing/slowing down.1

Irrespective o the patients age, good

candidates or multiocal contact lenses

possess some level o dissatisaction

with their current correction in at

least part o their day-to-day lie. Most

importantly, practitioners must frst

identiy, and then seek to quantiy,

this level o dissatisaction, as it will

orm the benchmark against which all

alternative corrections are compared.

Commnicating eectively

an etablihing realiticexpectationFailure with multiocal contact lenses is

oten due to poor communication rather

than the lens technology. The practitioners

ability to establish realistic expectations

Pupil size and ambient light

Near add power

Aspheric optics

Centration and stability of the lens on

the eye

The perormance and advantages o

one lens type over another cannot be

simply attributed to, or example, whether

a lens is centre distance vs. centre near

or whether a lens has a higher or lower

add power. There are two commercially

available centre-near silicone hydrogel

multiocal contact lenses with aspheric

optics (Figure 1), namely the PureVision

Multi-Focal (Bausch & Lomb) and the Air

Optix Aqua Multifocal (CIBA Vision).

Such lenses achieve a dierent balance

between distance and near vision due to

dierences in the specifc lens design.

For example, the Acuvue Oasys or

presbyopia (Johnson and Johnson Vision

Care) uses a centre-near concentric

ring design, which is believed tooer control o the distance/near

balance according to ambient light.

What o patient think abotmltiocal contact lene?Several studies have investigated the

objective and subjective visual perormance

o multiocal contact lenses, specifcally

by comparing them to monovision.

Objective assessments included visual

acuity (VA) and contrast sensitivity

(CS)7,8 whilst subjective assessments have

centred on intent to purchase, satisaction,

and questionnaire responses.2,9-11

When comparing the objective visual

perormance o monovision and the

PureVision Multi-Focal lens, Gupta

et al.7 ound signifcant dierences in

the perormance o the two modalities.

Most notable was the improvement

in high contrast distance and near VA

whilst wearing monovision (p


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at the initial ftting stage is commonly cited

by lens manuacturers as one o the key

milestones in achieving success. However,

this should not constitute an opportunity

or the practitioner to repudiate all

responsibility or what is about to happen.

The practitioners choice o language can

have a large impact on the success/uptake

o multiocal lenses once ftted. Describing

the visual outcomes with terms such as

slightly compromised vision or vision

that is not as good as spectacles does

not provide the patient with either a

positive or necessarily realistic outlook

on what might be achieved. It is ar better

to describe the visual outcomes using

terms such as unctional all-round vision

or achieving a better balance between

distance and near vision. In the broadest

terms, practitioners should describe what

the patient stands to gain rather than what

they stand to lose (Table 1). This approach

will improve the likelihood o successand oer patients a compelling reason

to proceed; the approach should be akin

to recommending variocal spectacles

to a new wearer by being realistic about

expectations and having a positive outlook.

How o I know which len powerto elect initially?There is no one size fts all approach to

multiocal contact lenses. Each lens has its

own manuacturer approved set o ftting

guidelines, which should be ollowed

or every new patient. Following the

manuacturers guidelines will increase

the rate o success and reduce unnecessary

in two stages; short-term (20-30 minutes)

and long-term (1 week and beyond). In

an ideal situation a practitioner would

be able to assess the best possible

visual perormance achievable shortly

ater initial lens application, giving

an indication o success or ailure,

but in practice this is not the case.

shortterm aaptation

A period o 20-30 minutes is usually

required or the lenses to stabilise and

or any initial physiological reaction (eg,

lacrimation) to pass. During this time is

it advisable that the patient leaves the

consulting room and be given opportunity

to perorm a mixture o visual tasks eg,

looking into the distance, reading the

time on their watch, viewing their mobile

phone, alternating between distance

and near vision tasks etc. in a real world

environment. Upon their return, patients

should be encouraged to subjectively

score their distance and near vision eg, on

a scale o 1-10, to provide the practitioner

with a relative indication o their

satisaction. This is the recommended

clinical standard2 and provides the

practitioner with a benchmark to work

against in order to obtain the optimal

balance o distance and near vision when

refning the lens power. Furthermore,

subjective grading o vision may be

sensitive to small changes in lens powerthat cannot be identifed using objective

methods; equally, it has been shown that

chair time. In the same way that not all

patients will adapt to variocal spectacles,

it would be unrealistic to expect every

patient to adapt to multiocal contact lenses.

However, by ollowing the manuacturers

ftting guidelines, practitioners can

expect success rates o 72-79%.1 The

manuacturers ftting guidelines are

derived rom experience gained during lens

development, oten involving hundreds,

i not thousands, o patients.1 Following

the manuacturers ftting guidelines also

serves as an important indicator o the

point at which no urther adjustments to

lens power should be made, or example,

in the relatively small percentage o

instances where the patient doesnt

achieve the visual outcome they require.

AaptationUnlike most other types o contact lenses,

multiocal lenses require a period o

adaptation in order or the practitioner

to obtain a true sense o the visual

perormance.13 Adaptation is best thought o

Table 1

Guidance on communication when discussing multiocal contact lenses

Words/phrases to avoid Words/phrases to use

Compromise

Trade-o

Not perect

Not as good as spectacles

Loss o crispness/slightly hazy/oggy

Functional vision

Balance between distance and near

Re-prioritisation o vision

Reduced dependence on reading glasses

Likely to use your reading glasses 60-90% less

Figre 3

Example case summary o a presbyopic multiocal contact lens ftting


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where objective vision appears reduced

or improved there may be no correlation

with a patients subjective opinion.13

Longterm aaptation

As or frst time variocal spectacle wearers,

patients who are new to multiocal contact

lenses commonly require a longer period

o adaptation to get used to their new

vision. This is where the real trial o the

lens begins. It is important to ulfl this

part o the lens ftting process as subjective

perormance o the lenses can change

signifcantly rom the initial fndings.13

Improving otcomeGiance note 1

It is important to check that the distance

vision is optimised. In general, this

process involves measuring the objective

VA and subjective opinion binocularly;

add as much plus power to the distance

prescription as the patient will accept,up to the point where urther plus power

causes a reduction in VA.14 This will

enable the add power to be kept to a

minimum. The process should be done

in good illumination. Begin with the

dominant eye and increase plus power

in 0.25D steps. Repeat this process for the

non-dominant eye. Use handheld trial

lenses to carry out the over-reraction and

avoid using a phoropter or trial rame

(Figure 2). I minus lenses are required to

improve distance vision act cautiously.

Only reduce the plus power i there is a

distinct improvement in subjective vision.

Practitioners should be wary of chasing

contrast improvements when over-

reracting with minus powered lenses.

Giance note 2

Only when the distance power is

optimised should near vision be assessed,

since small changes to the distance

power can have a proound eect onnear vision.1,14 Aim to keep the near add

power as low as possible. I subjective

the overwhelming majority (78%) chose to

use both to combine the benefts o each.15

smmaryMultiocal contact lenses have evolved

signifcantly over the past decade and

increasingly practitioners are ftting them.

However, the presbyopic population

remains the least developed segment o

the contact lens market and thus presents

a very real opportunity to the industry.

Emerging presbyopes stand to gain the

most rom multiocal contact lenses, as

they have greater amiliarity with contact

lenses and possess a wider variety o

visual requirements than more established

presbyopes. Adopting a ftting strategy

that conorms to the manuacturers ftting

guidelines will improve the success

rate and reduce unnecessary chair time.

Practitioner communication, particularly

during the pre-ftting discussion, also

plays a signifcant role in the outcome

achieved. It takes practice to achievehigh and reliable success rates with

multifocal lenses. Practitioners should

seek guidance rom experienced peers or

consult with contact lens manuacturers

or ftting guidance and education.

Abot the athorDr Cameron Hudson is the proessional

services manager for CIBA Vision, UK.

Reerence

See http://www.optometry.co.uk/clinical/index. Click on the article title and then

download reerences

Figre 4Example case summary o an emerging presbyopic multiocal contact lens ftting

near vision is not close to an acceptable

level consider adding a small amount o

positive power to the distance component

in the non-dominant eye (eg, +0.50D).1

Giance note 3

Follow the manuacturers ftting

guidelines, even i a patient isnt achieving

high scores subjectively. Provided that the

patient is willing and that they objectively

achieve a standard o vision that rom

a medico-legal perspective is deemedacceptable, encourage an extended

trial (4-7 days) and re-assess the visual

perormance ater this time. I, at the end

o the extended trial, there are no urther

adjustments to the lens power, ormulate

a succinct way to summarise what you

have achieved (Figures 3 and 4). This will

allow the patient to ormulate in their own

mind about whether the vision achieved

justifes the lenses being dispensed.

Which metho o correction oprebyope preer?Given that there is no single correction

that suits all presbyopes or all activities

it is important that clinicians consider

all options to satisy an individuals

liestyle and visual demands. This may

involve combining the benefts o several

correction options in order that the relative

advantages and disadvantages can be

maximised and minimised, respectively.

It has been demonstrated that whenspectacle-wearing presbyopes are given the

opportunity to try multiocal contact lenses,


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1. Which age grop o patient i LEAsT repreente within thecontact len intry?

a. 20-27 yearsb. 28-35 yearsc. 35-45 years

d. 45 years and above

2. The perormance o a imltaneo eign mltiocal contact leni epenent pon which o the ollowing actor?

a. Relative size o the distance and near optic zonesb. Relative position o the near optic zones on the lensc. Pupil size and ambient lightd. All o the above

3. Accoring to Woo et al. which o the ollowing tatement reectpatient opinion on mltiocal contact lene?

a. Patients generally preer monovision over multiocal contact lensesb. Patients generally preer multiocal contact lenses over monovisionc. Multiocal contact lenses and monovision are liked equally

d. Neither multiocal contact lenses nor monovision are liked by patients

4. Which o the ollowing term wol be MOsT appropriate to ewhen ecribing the vial otcome with mltiocal contact lene?

a. They provide a slight loss o crispnessb. They provide unctional vision or distance and nearc. They provide a compromise between distance and near

d. They provide vision which is not as clear as with spectacles

5. When refning the mltiocal contact len power, practitioner

hol:a. Aim to provide the most plus distance reractionb. Preerably use a phoropterc. Assess vision monocularly

d. Assess vision in low room illumination

6. When given the opportnity to experience mltiocal contactlene, what proportion o variocal wearer preerre to combine

the beneft o both pectacle an contact lene?

a. 35%b. 78%c. 54%

d. 63%

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on March 14 2011 Yo will be nable to bmit exam ater thi ate anwer to the mole will be pblihe onwww.optometry.co.k. CET point or thee exam will be ploae to Vantage on March 21 2011.Mole qetion

1. Which o the ollowing tatement i FALsE?a) Currently an estimated 700,000 people in the UK have dementiab) Two thirds o people with dementia have Alzheimers diseasec) 90% o people with Alzheimer s disease have visual unction decline

d) Visual system disturbances can pre-date maniestations o dementia

2. Which o the ollowing i a typical vial ymptom o Alzheimer

ieae?a) Diculty with reading at nearb) Blurred vision, not due to rerac tive error or eye diseasec) Diculty picking out objects in a group

d) All o the above

3. Alzheimer ieae oe NOT aect which o the ollowing?a) Tear ductsb) Crystalline lensc) Optic nerved) Retina

4. Motion proceing i NOT aociate with which o the ollowing?a) Dysunction o magno- and konio-cellular processingb) Dysunction o orm identifcationc) Diculty interpreting patternsd) Mental conusions

5. Which o the ollowing tatement abot aeing vial nction in

Alzheimer ieae i FALsE?a) The Vistech chart reveals loss o high spatial requency contrast sensitivity

b) Frequency doubling technology is preerred or testing visual feldsc) The City University test is preerred or assessing colour visiond) Threshold visual felds are more suitable or monitoring co-morbidity with

glaucoma

6. Which o the ollowing conition reqire an inivial

poeing a riving licence to notiy the dVLA?a) Alzheimers diseaseb) Parkinsons diseasec) Glaucomad) All o the above

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Multifocal Contact Lenses(1)