*Lighthouse National Survey on Vision Loss 1995

Presented by:

Bob ScannellTerritory Manager : Florida & PREschenbach Optikof America

3/09

Low Vision Care…What’s It All AboutAn Overview

1. Definitions and Demographics

2. Basics of Low Vision Optics

3. One simplified model for thedispensing of Low Vision Devices

4. Low Vision Device Overview

Outline

What is Blindness?Depends on how defined…

Can’t see anything, no light perception (NLP)

Legal definition (20/200 or worse in better eye or less that 20 degrees field of view in better eye)

Definitions & Demographics

What is Low Vision?Depends on how defined…

Common definitions by acuity (WHO: 20/ 60-20/ 400, etc.)

Vision that cannot be corrected with glasses, contacts or through the use of therapeutic or surgical treatment.


What is Low Vision?

Uncorrectable vision loss that impairs one’s ability to function normally.


What causes Low Vision?

Many different underlying eye diseases

Definitions &Demographics

Macular

Degeneration


Diabetic

Retinopathy


Glaucoma


Cataracts


Other eye diseases causing LV Retinitis Pigmentosa: affects 100,000 people (Foundation

Fighting Blindness); no cure

Corneal Disease

Optic Nerve Atrophy

Strokes(statistics from “Statistics on Vision Impairment: A Resource Manual” Arlene Gordon

Research Inst., Lighthouse Int., April 2002.)


How many people are blind in the US?

By definition of NLP: 260,000 in US (Am. Foundation for the Blind, 2001)

By legal definition, 1.3 million in US (AFB, 2001)


How many people are visually impaired (have low vision) in the US?

Using definition of functional vision loss (self reported), almost 20 million in US (Lighthouse International)


What is Low Vision Care? Service provided by eyecare or rehabilitation

professionals to help maximize the remaining visionin those that are visually impaired

It can include lifestyle adjustment training,orientation & mobility training, recommendation ofthe use of non-optical devices and the dispensing oflow vision aids


What are Low Vision Aids?Optical, non-optical and electronic

products that assist those that are visually impaired


Why offer Low Vision Care? Helps your patients:

-improves their quality of life

-helps them regain theirindependence

-helps them live their life safely


Why offer Low Vision Care? Helps your practice:

-adds revenue

-fulfills your obligation to meet your patient’s needs as they grow older (continuum of care)

-large need: only30% of those that are visually impaired use an optical device such as a magnifier or telescope*


*Lighthouse National Survey on Vision Loss 1995.

When should Low Vision Care beoffered?

When they are legally blind (20/200 or <20°)?

After they’ve had an accident (tripping, falling,driving) or taken the wrong medication, missedpaying bill?

When they ask for it?


When should Low Vision Care be offered?

Assoon as possible!

Should offer low vision care as soon as patient is diagnosed with one of the diseases causing low vision.


Early Intervention improves the success rate of LV patients & practitioners:

Patients are more emotionally/ psychologically stable

A larger choice of low vision aids available (more categories)

The low vision aids that are available are easier-to-use (lower in power, wider fields of view, requireless training)

Builds a relationship with practitioner


Variables in Low Vision: Magnification

Illumination

Education


Magnification: Why do Low Vision Aids help the visually impaired?

Underlying eye pathologies that cause low vision cause one or more of the following conditions:

1) Central Field Loss 3) Cloudymedia

2) Peripheral Field Loss


Central Field Loss (AMD, DR)


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Peripheral Field Loss (Glaucoma, RP)


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Cloudy media (Cataracts)


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Ways to Magnify: Relative Size

RelativeDistance

Angular

Electronic


Illumination Why is illumination important?

Improves contrast


Without Illumination w/ illumination


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Types of Illumination Incandescent


Types of Illumination Halogen


Types of Illumination LED

(light emitting diode)

Fluorescent


Education Training on the use and care of the low vision aid is

critical for a successful outcome

Other training (eccentric viewing, etc.) also very helpful


Basic Optical definitions Diopter (D) is a metric measure of lens power

1D lens focuses at 1 meter (40”)

1D = 1m/ F (= 1000 mm/ F = 40”/ F)

Specific, measurable

Basics of Low Vision Optics

F

Basic Optical definitions

Times Magnification (X) is the ratio of the size of a magnified retinal image to the original

If use a 2X magnifier, makes image on back of retina twice as big

Subjective term


Basic Optical definitions Diopter (D) versus Times Magnification (X)

According to ANSI (American NationalStandards Institute), 4D = 1X

If have a 4X magnifier, equivalent to 16D


Types of lenses

• Refractive

• Diffractive


Types of lenses

• Refractive lens

• Bends light

• (due to differences in the index of refraction between 2 materials)


Types of Refractive lenses

• Biconvex

• Made of 2 surfaces of

equal curvature



• Aspheric

• Made of 2 surfaces of

different curvature



• Aplanatic

• Made of 2 plano-convex

lenses


Diffractive Lens

Uses principle of

diffraction:

• Deflects light

• (ex. hole in curtain)


Many different ways of offering Low Vision Care

• American Academy of Ophthalmology’s SmartSightprogram:

• 4 levels of care:

• Levels 1 & 2: recognize & refer out for LV care

• Level 3: offer LV Services/ Rehabilitation

• Level 4: offer LV Services/ Rehab. and RehabilitaitonTraining

Practice Management

7 Steps to Dispensing Low Vision Aids

Step 1: Make sure the patient is under the current care of an eye doctor and is wearing their best correction

Practice Management


Step 2: Determine patient’s visual goals

How? Use pre-evaluation questionnaires that ask thepatient their goals

Practice Management


Step 3: Determine the magnification required for the patient’s primary visual goal.

How?

Practice Management

Determining Magnification

-Reading chart

-Kestenbaum’sRule: Inverse of SnellenAcuity

20/ 200 200/ 20 = 10 units = D so 10D

Practice Management

20/ 800 40D 10X

20/ 630 32D 8X

Determining Magnification

- Relationship of the Best Visual Acuity / Visual Acuity of the Task

- -ex. Pt. has 20/ 200 acuity and wants to read (requires 20/ 50 acuity)

20/ 200 delete numerators, simplify denominator 20/ 50

200/ 50 4 X

Practice Management


Step 4: Determine the impact of illumination.

• Choose light source most appropriate

• Teach patient how to use illumination properly

• Introduce concept of contrast-enhancement

Practice Management

Introduce concept of contrast enhancement

Introduce concept of contrast enhancement


Step 4: Determine the impact of illumination.

• Test contrast sensitivity function

Practice Management


Step 5: Select the vision aid(s) appropriate for the patient’s primary visual goal.

Some LV practitioners confirm required magnification (and show immediate success) with a video magnifier

Practice Management



Practice Management

Magnification level shown on screen



Problem: How do you decide which product is best?

Practice Management

No one low vision aid will work for every task

Each category has its own benefits and limitations

(e.g., for reading a prescription bottle, a hand-held magnifier is best; for reading a book, a stand magnifier is best)

Practice Management

Low Vision devices chosen based on:

1. The duration of the task presented

-short-term or “Spotting”

-long-term or “Extended”

2. The distance of the task

-Near, intermediate, or far

Practice Management



We will discuss the major categories of low vision aids and will cover:

1) two rules for each category

2) benefits and limitations of each category

Practice Management



Hand-heldMagnifiers

Practice Management

Rules for Proper Usage

of Hand-held Magnifiers: Hold lens parallel to the object to

be viewed

Hold lens at its focal length fromobject

Practice Management

Benefits of Hand-held Magnifiers:

familiar design

easy to use (finding focal distance, etc.)

versatile (can view flat or round objects)

relatively inexpensive

portable

Practice Management

Uses for Hand-heldMagnifiers:

Reading prescription bottles, pricetags, menus, maps, telephone books

Looking at photos, thermostats,oven dials

Practice Management

Limitations of Hand-heldMagnifiers:

need 1 hand to hold product (nothands-free)

gets tiresome after a while

not good for patients with tremors

only good for near tasks

Practice Management



StandMagnifiers

Practice Management


of Stand Magnifiers: Hold stand magnifier firmly against

object to be to be viewed

Adjust the eye-to-lens distanceaccordingly

Practice Management

Benefits of Stand Magnifiers: good for patients with tremors

don’t get as tired—don’t have tosupport weight of product

portable?

fixed focal length

lens mounted parallel to object

Practice Management

Uses for Stand Magnifiers: Reading newspapers, magazines,

books

Looking at photos

Practice Management

Limitations of StandMagnifiers:

object specific (can only view flatobjects)

relatively more expensive

need 1 hand to hold product (nothands-free)

limited field of view

Practice Management



Spectacle Magnifiers

Practice Management


of Spectacle Magnifiers: Hold object to be viewed at the

focal length of the eyewear

Move material horizontally across the field of view instead of moving head

Practice Management

How do Spectacle Magnifiers work?

ABCD

EF

ABCD

EF

y’

y

Benefits of SpectacleMagnifiers:

wide field of view

good for patients with tremors

hands-free

portable

what they always ask for--“Can’t Ijust get a better pair of eyeglasses?”

Practice Management

Uses for Spectacle Magnifiers: Reading books, menus, sheet music,

handi-crafts / hobbies

Looking at photos

Practice Management

Limitations of SpectacleMagnifiers:

short working distance

poor cosmesis

refractive considerations

Practice Management



Telescopes

Practice Management

How do Galilean Telescopes work?

Galilean Telescopes:• Simple 2-lens design

• Bright

• Shorter barrel

• Lighter weight

• Easiest to fit

• Typically afocal

• Limited power range (< 5X)

How do Keplerian Telescopes work?

• Broad power range (up to 10X)

Keplerian Telescopes:• Multi-element design

• Not as bright

• Longer barrel

• Heavier

• Challenging to fit

• Typically focusable


of Telescopic Vision Aids: Locate object to be viewed through

telescope

Focus telescope on object

Practice Management

Benefits of Telescopes: only category that will magnify intermediate

or distant objects

offers longest working distance when usedfor near objects (4x spec.: 40/ 16=2.5”; 4xtel.:= 10”—4 times the distance!)

parallel light emerges when used properly

mounted telescopes are hands-free

portable

versatile

Practice Management

Uses for Telescopes: Watching TV, movies, theater

Looking at supermarket aisle signs,bus numbers

Reading sheet music

Looking at a computer screen

Practice Management

Limitations of Telescopes: limited field of view

refractive considerations

most require focusing

relatively expensive

poor cosmesis

Practice Management



Video Magnifiers

Practice Management


of Video Magnifiers: Locate object to be viewed with

camera

Focus image and adjustmagnification as needed

Practice Management

Benefits of Video Magnifiers: provide variable magnification

allow text to be manipulated (whiteon black, etc.)

facilitates binocular viewing

provides highest levels ofmagnification

versatile

Practice Management

Uses for Video Magnifiers: Reading magazines, newspapers,

letters

Looking at photos

Personal care / hygiene

Looking at supermarket aisle signs,menus

Practice Management

Limitations of VideoMagnifiers:

relatively expensive

desk-top versions not portable

technology changing rapidly

Practice Management



Based on each category’s benefits & limitations, each is good for certain tasks.

Practice Management


Step 6: Train the patient

in the use and care of the

vision aid.

Practice Management


Step 7: Schedule a follow-up visit with the patient.

Practice Management

For more information on Low Vision Care, use these resources:

• Your professional association

• Conferences

• Journals

Practice Management

For more information on Low Vision Care, use these resources:

• Eschenbach

• Have 12 different modules on various topics—provided to you in your office by your local Territory Manager

Practice Management

Practice Management

Thank you!

Low Vision Care…An Overview

Documents

*Lighthouse National Survey on Vision Loss 1995