Dr. Divyesh P. ShahSight First Technical Advisor, MD 322

Lions Clubs International Foundation

LOW VISION AIDS

LOW VISION DEFINITION

“A PERSON WITH LOW VISION IS ONE WHO HAS

IMPAIRMENT AND /OR STANDARD REFRACTIVE

CORRECTION AND HAS A VISUAL ACUITY OF LESS THAN

6/18 TO LIGHT PERCEPTION IN THE BETTER EYE OR A

VISUAL FIELD OF LESS THAN 10 DEGREES FROM THE

POINT OF FIXATION, BUT WHO USES OR IS POTENTIALLY

ABLE TO USE , VISION FOR THE PLANNING AND / OR

EXECTUION OF A TASK” (WHO/PBL/93.27)

What is Low Vision?

• Low vision can be described as reduced vision which cannot be corrected by optical or surgical means

World Health Organisation definition: Best corrected VA less than 6/18 to PL or a Visual field of less than 10 degrees in better eye

Low Vision and Low Vision Rehabilitation:

• A person with a significant reduction in visual acuity due to ocular disease that is not correctable by surgery, conventional eyeglasses or contact lenses has Low Vision

• The process of helping a person with low vision achieve the highest level of visual function, independence, and quality of life possible is Low Vision Rehabilitation

• The role of a low vision specialist (optometrist or ophthalmologist) is to maximize the functional level of a patient's vision by optical or non-optical means called LOW VISION AIDS

A Global Estimate of Low Vision Care Needs

• 148 million visually disabled (blind+ low vision, ref. ICD-10)

8 million blind, without any perception of light

140 million partially sighted 140 million partially sighted

(of whom 30 million blind, but having some residual vision)(of whom 30 million blind, but having some residual vision)

25%75%

35 million in need of low vision care

105 million in need of cataract surgery and/or routine refraction

• Worldwide, for each blind person, an

average of 3.4 people have low vision, with

country and regional variation ranging from

2.4 to 5.5.

95% of people with low vision have some level of useful vision.

• Those with worsening sight and the prognosis of eventual blindness are at comparatively high risk of suicide

• These people can be helped with Low Vision Aids

Lack of Services – The Impactto Children

• For children, the lack of low vision

services means:

– Developmental delay

– Loss of educational opportunity

– Isolation

– Dependency

– Inability to participate in family and society

– Put into the category of blind and they are provided

with braille instead of general stream.

Lack of Services – The Impactto Adults and Seniors

For adults, the lack of low vision

services means

• – Isolation

• – Dependency

• – Inability to participate in family and society

• – Unemployment/underemployment

• – For the elderly it may mean increased risk

• for psychological and health effects; even

• mortality

Woeful lack of awareness

• Patients

• Society

• Doctors

• Opthalmologists

• Facilities providing services LACK OF AVAILABILITY OF SERVICES

AND TRAINED MANPOWER

Conditions causing Low Vision

Include :• A R M D- central loss• Diabetes- retinopathy Laser treatment• Retinal Disorders• Stroke +/- Field Loss• Nystagmus• Congenital Conditions• Multiple Sclerosis• Glaucoma

Central Loss

• Macular Degeneration

VISUALVISUAL

EFFECTSEFFECTSLOW VISIONLOW VISION

AIDSAIDSV a: may vary with the extent of V a: may vary with the extent of the deg: with dry-stage the deg: with dry-stage ARMD,acuity can range from ARMD,acuity can range from 20/20 to 20/400.With wet-stage 20/20 to 20/400.With wet-stage (exudative) ARMD,the acuity can (exudative) ARMD,the acuity can show loss worse than 20/400.show loss worse than 20/400.

Main problem is very difficulty Main problem is very difficulty to reading or writing. to reading or writing.

Should be prescribe optical glass Should be prescribe optical glass & direct illumination should be & direct illumination should be recommended for all near tasks. recommended for all near tasks. Most of the patients respond Most of the patients respond well to magnification at distance well to magnification at distance & near. Non-optical aids . CPF & near. Non-optical aids . CPF lens improved contrast & lens improved contrast & control glare.control glare.

Age-related Macular degeneration

• The most common cause of visual loss in Western countries

• >50% of all registered VI

• >70% of all visually impaired over 75 years of age

Homonymous hemianopia

Glaucoma

VISUALVISUAL

EFFECTSEFFECTS LOW VISION LOW VISION

AIDSAIDSBlurredBlurred vision which is gradual. vision which is gradual. Photophobia ,seeing halos Photophobia ,seeing halos around light, opacity or haze on around light, opacity or haze on lens, central visual acuity is lens, central visual acuity is generally unaffected until the generally unaffected until the end stage of this disease.end stage of this disease.

Visual loss in end –stage Visual loss in end –stage glaucoma pt: creates problem glaucoma pt: creates problem with orientation & mobility.with orientation & mobility.

CCTV or max are useful because CCTV or max are useful because increase contrast & brightness increase contrast & brightness along with magnification,CPF are along with magnification,CPF are beneficial in reducing glare, beneficial in reducing glare, reverse telescopes can be used to reverse telescopes can be used to enhance visual field, flashlight enhance visual field, flashlight can be helpful for night travel, can be helpful for night travel, long cane also helpful for travel long cane also helpful for travel (end-stage).(end-stage).

End Stage Glaucoma

Albinism

VISUALVISUAL

EFFECTSEFFECTSLOW VISIONLOW VISION

AIDSAIDSAlbinism has the most Albinism has the most severe effect on visual severe effect on visual acuity, ranging from 20/200 acuity, ranging from 20/200 to 20/400.to 20/400.

Photophobia, may high Photophobia, may high refractive error,refractive error,

nystagmus, color vision is nystagmus, color vision is normal. normal.

Correct refractive errors. Correct refractive errors. Controlling illumination sun Controlling illumination sun lenses, CPF & color contact lenses, CPF & color contact lenses or pin hole cl, visors lenses or pin hole cl, visors & hat can often reduce & hat can often reduce photophobia. Telescope for photophobia. Telescope for distance. distance.

Retinopathy

VISUALVISUAL

EFFECTSEFFECTSLOW VISIONLOW VISION

AIDSAIDSDepending on the severity of Depending on the severity of retinopathy, visual acuity retinopathy, visual acuity ranges from 20/20 to total ranges from 20/20 to total blindness. Loss of color vision. blindness. Loss of color vision. Most commonly , decreased Most commonly , decreased vision is a result of lens vision is a result of lens changes (due to fluctuation in changes (due to fluctuation in blood sugar level) or macular blood sugar level) or macular edema. edema.

Correct refractive error.CPF & Correct refractive error.CPF & sun lenses that block blue sun lenses that block blue wavelenths may inprove wavelenths may inprove contrast & eliminate glare & contrast & eliminate glare & photophobia. Direct photophobia. Direct illumination for near tasks is illumination for near tasks is generally helpful. Prismetic generally helpful. Prismetic glass ,hand mag & CCTV may glass ,hand mag & CCTV may helpful for near task. helpful for near task.

Diabetic retinopathy

Retinitis Pigmentosa

VISUALVISUAL

EFFECTSEFFECTSLOW VISIONLOW VISION

AIDSAIDSCentral vision ranges from Central vision ranges from 20/20 to no light perception. In 20/20 to no light perception. In early stages of the disease, early stages of the disease, acuity usually remains normal. acuity usually remains normal. In later stages, acuity may In later stages, acuity may become moderately to severely become moderately to severely decreased secondary to lens or decreased secondary to lens or macular changes. Photophobia, macular changes. Photophobia, night blindness, color vision night blindness, color vision problem. Slow reading & problem. Slow reading & mobility problem. mobility problem.

Refractive error should be Refractive error should be evaluated carefully. CCTV or evaluated carefully. CCTV or Max are useful (increasing Max are useful (increasing contrast & brightness along contrast & brightness along with magnification ). Prismatic with magnification ). Prismatic lens & good illumination lens & good illumination helpful for near task.CPF lenses helpful for near task.CPF lenses are helpful for improving are helpful for improving contrast & reducing glare. contrast & reducing glare. Reverse telescoReverse telescope for distance. pe for distance. Vision rehabilitation is also needed.Vision rehabilitation is also needed.

Purpose of Low Vision Assessment

• Low vision rehabilitation allows people to resume or continue to perform daily living tasks, reading being one of the most important

• This can be achieved by providing non optical and optical devices as well as training in the use of residual vision

Assessment

• Establish patient’s understanding of eye condition

• Explanation given if necessary, backed up with written or taped information if required

• Aim to dispel myths: -Tend to retain peripheral vision in ARMD -Can’t ‘use up’ remaining vision -Don’t feel guilty about using sight

REFRACTION

• Encouraged to have up-to-date refraction

• Many patients with low vision benefit from having separate readers, rather than using bifocals or varifocals, especially if a magnifier is to be used, or eccentric viewing taught

Low Vision ExaminationVision Test

Prescription ofVisual Devices

Counseling and Emotional Support

• Counselling and Emotional Support- Patients may experience similar feelings to the various stages of bereavement

• Charles Bonnet syndrome- patients need reassurance that their visual hallucinations are a common symptom of visual loss

Establish visual needs and requirements

• Near / Distance

• Hobbies / Leisure

• ‘Survival’ reading such as : correspondence

labels / prices

food packets & use-by dates

medication instructions/syringe markings

Optical Aids

• Magnification: aim to use lowest possible

• Higher magnification =smaller magnifier lens, therefore smaller field of view

Optical Aids

• Choices: hand/stand/lighted/

dome depends on:

• Patient choice

• General health issues

• Task

Stand Magnifiers

• May be non-illuminated or illuminated with an LED

• Location of image inside of the focal point of the F1 requires accommodation or an add to resolve the image.

Distance and Near Magnification Systems

Distance Telescopes

• Used to magnify the apparent size of a distant object when the patient cannot move closer to the object

• Tasks: viewing faces across a room, grocery store isle markers, bird watching, sporting events, tv

Tints/Filters/Glare Control

Wrap around filters available to control both indoor and outdoor glare.

Optical coatings such as AR, and Polaroid lenses may reduce glare

Binoculars and MonocularsTV glasses and Clip ons

Macular Degeneration

• UVShields with UV protection.

Field expanding spectacle

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•Touch screens -are devices placed on the computer monitor(or built into it) that allow direct selection or activation of the computer by touching the screen.

Magnification with CCTV

• If the CCTV is viewed from a distance closer to the screen than 40cm, the total magnification. Achieved is the product of RDM x RSM.

Recent Advances in Low Vision

• Bioptic & Auto focus Telescope

• Computer soft wares

• Speech recognition softwares

• Multilingual.

• Braille output printers.

• CCTV / LCD display/portable

• Large /bold print bank statements and Utility bills

• Clipboards and reading stands

• Shades and Visors• Large button phone• Aids:Talking clocks,

watches, tins.• Talking microwave,

measuring jug and scales, spirit level and rulers

• Electronic colour detectors

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1. Listen, Listen and Listen..2. Detail explanation low vision rehab programme.3. Psychological management.4. Friendly advise & counseling.5. Important of follow up.

• The sooner the patient receives support, the better

• NSF for older people states that patients should be enabled to retain their independence

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• Low vision care AND Vision rehabilitation is the crying need of the day

• Low vision rehabilitation offers the practitioners a feel good niche and the patient a real choice to regain visual independence.

• A large section of totally underserved partially blind population is waiting to be served

WE HAVE TO MAKE SURE THAT WE ARE READY TO SERVE

THANK YOU