Retinal Dystrophies Guideline Outlines Low Vision Rehab Process

Dystrophy??
 A hereditary, symmetrical, congenital or later
appearing, slowly progressive affection,
presenting slight intrafamilial variation, and of
unknown etiology.

Dystrophy??
 It was suggested that conditions secondary to
systemic factors should not be considered
dystrophies, but the authors find it somewhat
artificial to exclude entities with systemic
manifestations from the definition.

 Retinitis Pigmentosa has been found to be
associated with systemic conditions that are
inherited and is called one of the retinal
dystrophies

Retinal Dystrophies
 Generalised photoreceptor dystrophies
 Typical retinitis pigmentosa
 Atypical retinitis pigmentosa

 Progressive cone atrophy

 Leber Congenital Amaurosis

 Stargardts disease and Fundus flavimaculatus

 Bietti corneoretinal crystalline dystrophy

 Alport syndrome

Retinal Dystrophies
 Generalised photoreceptor dystrophies
 Familial
benign fleck retina
 Pigmentary paravenous chorioretinal atrophy

 Congenital stationary night blindness

 Congenital monochromatism

Retinal Dystrophies
 Macular Dystrophies
 Juvenile Best macular dystrophy
 Multifocal Vitelliform lesions without Best disease

 Pattern dystrophy

 North Carolina macular dystrophy

 Familial dominant drusen

 Sorsby pseudoinflammatory dystrophy

Retinal Dystrophies
 Macular Dystrophies
 Benign concentric annular macular dystrophy
 Central areolar choroidal dystrophy

 Dominant cystoid macular oedema

 Sjogrens-Larsson syndrome

 Familial internal limiting membrane dystrophy

Goals
 Identify patients with visual impairment(s) who
might benefit from low vision care and
rehabilitation

 Evaluate visual functioning of a compromised
visual system effectively

 Emphasize the need for comprehensive
assessment of patients with impaired vision
and referral to, and interaction with, other
appropriate professionals

Goals
 Maintain and improve the quality of eye and
vision care rendered to visually impaired
patients

 Inform and educate other health care
practitioners and the lay public regarding the
availability of vision rehabilitation services

Goals

 Increase access for the evaluation and
rehabilitative care of individuals with visual
impairment(s), thereby improving their quality
of life.

 Vision rehabilitation
 As defined by the American Optometric
Association

 the process of treatment and education that
helps

 individuals who are visually disabled attain
maximum function, a sense of well being, a
personally satisfying level of independence,

 and treatment including, but not limited to, the
prescription of optical,

 non-optical, electronic and/or other treatments.

 The rehabilitation process includes the
development of an individual rehabilitation
plan

 specifying clinical therapy and/or instruction in

Quantifiers of Visual Impairment
 The ICD 10-ICIDH has employed the following
quantifiers:
 Visual Acuity

 Visual Field

 Contrast Sensitivity

 The approach is to use functional terms to
classify the type of Visual Field defect.

 This approach is a useful way to think of
problems the patient may encounter:

 …the patient may encounter:
 Novisual field defect, but a loss of resolution or
contrast throughout the entire visual field; general
haze or glare

 Central visual field defect

 Peripheral visual field defect

 For rehabilitation work, must know thing:
 Visualfield defect loss of contrast and
resolution

 Central VF defect

 Peripheral VF defect

 For the Guideline here on how to rehabilitate
the patients with retinal dystrophy,

 Low vision instruction, low vision training, low
vision therapy, vision rehabilitation theapy and
vision rehabiliatation training are synonymous

CARE PROCESS
 Diagnosis of Low Vision
 PatientHistory
 Ocular Examination
 Visual Acuity
 Monitor stability or progression of disease
 Assess eccentric viewing postures and skills
 Assess scanning ability( for patients with restricted field)
 Assess patient motivation
 Teach basic concepts and skills( ie to eccentrically view)
relevant to rehabilitation process

CARE PROCESS
 PatientHistory
 Refraction
 Use of JND technique

 Radical retinoscopy

CARE PROCESS
 PatientHistory
 Ocular motility and Binocular Vision Assessment
 Evaluate for the presence of nystagmus, ocular motility
dysfunction( eg poor saccades and pursuits)

 Look for strabismus, substandard binocularity, or diplopia

CARE PROCESS
 PatientHistory
 Gross assessment of ocular alignment( eg Hirschberg
estimation)

 Sensorimotor testing( Worth four dot test, red lens test)

 Amsler grid test, monocularly versus binocularly to
determine eye dominance and the possible need for
occlusion

CARE PROCESS
 PatientHistory
 Contrast sensitivity , monocularly versus binocularly to
determine eye dominance and the possible need for
occlusion

 Effect of lenses, prisms, or occlusion on visual functioning

CARE PROCESS
 PatientHistory
 Visual Field Assessment
 Central vs Peripheral VF defects
 Confrontation VF testing
 Amsler or threshold Amsler grid assessment
 Automated static perimetry
 Tangent screening
 Goldmann Bowl perimetry or equivalent kinetic testing

CARE PROCESS
 PatientHistory
 Ocular Health Assessment
 External examination( adnexa, lids, conjunctiva, iris, lens,
and pupillary response)
 Biomicroscopy( lids, lashes, conjunctiva, tear film, cornea,
anterior chamber, iris, and lenses)
 Tonometry
 Central and peripheral fundus examination with dilation
unless containdicated
Dilation not to be carried out prior to working with lenses

CARE PROCESS
 PatientHistory

 Supplemental Testing
 Contrast sensitivity testing
 Glare testing
 Visually Evoked Potentials (VEP)
 Electroretinogram( ERG)
 Electrooculogram( EOG)
 Colour Vision testing

CARE PROCESS

Management (Low vision
rehabilitation)

Rehabilitation
 The goals discussed earlier are met by;
 Improving distance, intermediate, or near vision

 Improving print reading ability

 Reducing photophobia and/or light-to-dark or
dark-to-light adaptation time

Rehabilitation
 The goals discussed earlier are met by;
 Improving the ability to travel independently

 Improving the ability to perform activities of daily
living

 Maintaining independence

 Understanding the diagnosed vision condition,
prognosis,and implications for visual functions

How to start??

 An optometrist should individualize
the management plan for each
patient while planning a course of
therapy.

How to start??

 An optometrist should CONSIDER
the following:
 Degree of VI

 Underlying cause( here retinal
dystrophy)

 Patient‟s age and developmental level

How to start??

the following:
 Overall health status of the patient

 Patient‟s adjustment to visual loss

How to start??

the following:
 Patient‟s expectations and motivations

 Patient‟s(cognitive) ability to participate
in the rehab

 Lens systems and technology available

Rehabilitation process
 Use of devices:

 Optical
Devices
 Non-Optical Devices
 RGPHOMeS

Looking at the statistics…
40
35
30
25
20 40
15
10
5 10 10 10 10
5 5 5 3 2
0

`
Presenting complaint Possible rehabilitation options

Difficulty in reading Refraction, lighting, high reading add
spectacles, hand held magnifiers, CCTV, large
prints/talking books

Difficulty in recognizing faces Refraction, fixation advice/training, lightning

Difficulty in watching TV Refraction, Changing Viewing distance, Fixation
advice /training telescopic magnifiers

Difficulty in navigation/mobility Orientation and mobility training, Refraction,
Telescopic magnifiers (for street signs)

`
Presenting complaint Possible rehabilitation options

Difficulty in using computer screens Text enlargement software, Screen
reading software, Refraction

Difficulty in kitchen/household tasks Lighting, Contrast advice, Hand
magnifiers

Difficulty in shopping Hand magnifiers, Portable lightning,
Handheld CCTVs

Difficulty in hobbies Refraction, Galilean Telescopes, Text
(reading, music, gardening, painting) enlargement

 Eccentric Viewing
 Eccentric viewing refers to the technique
of
 observing a scene with the peripheral
retina, by moving the damaged fovea
away from the object of interest

 Due to the lower density of photoreceptors
and greater number of photoreceptors per
ganglion cell in the peripheral retina,
 visual acuity will be far worse as that in the fovea.

 This strategy can, however, provide an
unobstructed view of the scene

Retinitis Pigmentosa
Usher Syndrome
Hallgren‟s Syndrome
Refsum‟s syndrome

 Prognosis:
worst prognosis severe Vision loss by 4th
 XL-
decade

 ARor sporadic cases-favourable with retention of
CF until 5th decade

 ADbest prognosis and CF present beyond 5th
decade

 ERG in RP
 Decreased in fERG
 Early pERG may be normal,

Later gets abnormal
 Amplitude reduction in the
periphery that corresponds to
VF defect

CHARACTERISTICS OF
DISEASES
Dark Line in Retina
Decreased Night Vision

Loss of Peripheral/Central Vision

Decrease in Visual Acuity

Functional Implications

 Peripheral vision lost
 Limited visual field
 Limited mobility
 Debilitating glare
 Extreme sensitivity
of light
 Eventual Blindness

Rehabilitation

 Wearing glasses
 Low vision devices
 Magnification and
illumination of
objects

Rehabilitation

 Field enhancers are
employed since
visual field is
markedly
constricted.

Rehabilitation

 So how is peripheral VF defect
management launched?

Rehabilitation

 Consider the goals as given by the
AOA and work under the following
five areas:
 Maximized VA
 Glare and photophobia control
 Magnification
 Field enhancement techniques
 Referrals for additional services

Rehabilitation

AOO and work under the following
five areas:
Maximized VA
Visual Acuity
 VA testing at appropriate distance so as
not to overwhelm the field with the letter
size
RP patients have difficulty seeing a
larger object at near

Rehabilitation

five areas:
Maximized VA
Visual Acuity
Proper illumination( towards a
brighter side) depending on other
ocular associations, Cataracts, for
example

Rehabilitation

five areas:
Maximized VA
Refraction
Allow for eccentric viewing(EV)
Encourage the EV if the px achieves
better VA

Rehabilitation

five areas:
Maximized VA
Binocularity
The asymmetric nature of RP makes
it difficult for pxs to maintain healthy
fusion because of differences in the
acuity( > 2 lines)

Rehabilitation

five areas:
Maximized VA
Binocularity
Also the frequent association of
nystagmus supports the binocularity,
for monocularity seems to worsen
nystagmus.

Rehabilitation

five areas:
Glare and photophobia control
Glare and photophobic sensitivities
???
Reduced contrast sensitivity, slower
responses to dark adaptation and
secondary media defects…

Rehabilitation

five areas:
Glare and photophobic sensitivities
???
The RPE tends to absorb less light
hence supports light scattering.
Glare interferes with the middle and

Rehabilitation

five areas:
Use of various lenses like
Corning, NoIR.

These absorb wavelengths towards
blue that are responsible for more

Rehabilitation

five areas:
Corning Lenses
CPF 550(Amber) esp for RP
NoIR filters
4% Dark Plum
2% Medium Plum

Rehabilitation

five areas:
Corning Lenses
CPF 550(Amber) esp for RP
NoIR filters
65% Yellow
49% Red

Rehabilitation

five areas:
Peaked caps
Tinted screen CCTVs
Also use of typoscopes

Rehabilitation

five areas:
Illumination
Incandescent lamps( 75-100)

Adequate light ( natural /
lamp) for daily tasks

Rehabilitation

five areas:
Place the lighting source behind
the px
So as to do away with the possible
unwanted glare
Place it to the side of the

Rehabilitation

five areas:
Magnification
 In peripheral field defects like in RP, the
minimal magnification to be provided coz
the stimulation of the peripheral retinal
may be of little or no value.

Rehabilitation

five areas:
Magnification
Use of microscopes in later stages
Also handheld magnifiers, stand
magnifiers

Rehabilitation

five areas:
Visual Field
RP shows a cone shaped visual
field.
Cone shaped??
The patient will show a geometrically
expanded field with increased testing

Rehabilitation

five areas:
Visual Field
Enhancers
Prism
Minus lens
Mirror
Reverse Telescope

Prism

E.g.. Fresnel prism

Interpretation
 When peripheral vision loss is severe
(leaving central visual fields of less than
20°), mobility can be reduced.

 Clinical rehabilitation options in dealing
with tunnel vision using nonprismatic
methods are limited and have had variable
success

Interpretation
 Fresnel prisms may not cause the same
central visual field degradation and have
added advantages of cosmetic
appeal, relative availability, and ease of
fitting

 The rationale for using prisms for field
expansion involves increasing scanning
effectiveness for patients, resulting in
improved peripheral awareness.

Interpretation
 We constantly scan our environment using low
spatial-frequency visual channels as we also
intermittently spot and view points of interest in
visual fields scanned, using various high
spatial-frequency visual channels.

 Cortical temporal multiplexing processes
create visual perception as we know it by
using the information obtained from scanning
and spotting.

Interpretation
 In the presence of tunnel vision, prisms project
peripheral fields information otherwise
unavailable, thereby enhancing the scanning
abilities of the eye.

 Enhanced scanning ability will produce new
spotting eye movements and together both
visual skills in fact expand peripheral field
awareness.

Also contrast sensitivity…

Contrast in Kitchen

Environmental Painted edges of Staircase
modification

Progressive Cone dystrophy
Inheritance Sporadic, AD or XL
Presentation 2nd -4th decade with
central Vf , CV
impairment
Signs …
ERG Photopic response-
abnormal
DA Cone segment abnormal
CV Deuteran-tritan defect
Prognosis Poor with eventual loss
of CV to the level of 6/60

Stargardt macular dystrophy
Inheritance Sporadic, AR
Presentation 1st -2nd decade with
central VF ,
malingering??
Signs …
ERG Photopic response-
abnormal
DA Cone segment abnormal
CV Red-green defect
Prognosis Poor with eventual loss
of CV to the level of 6/60

Characteristics…

Poor
Colour
Vision

Management
 Few guidelines,
 When scotoma is located right to the
macula, reading becomes difficult as the previous
word disappears—leading to difficulty in tracking

 When scotoma is located left to the
macula, reading becomes difficult as a new word
is readily invisible owing to a scotoma. So one
should use finger or marker to overcome problem

Management
 Refraction
 Magnification
 Non-optical devices
 Lighting and glare control
 Prism therapy
 Text Enhancement

Management
 To extrafoveate an object of regard

Management …EV
 Discussion:
 Besides reducing reading speed, the central
scotoma interferes with other visual functions
including
 Space perception
 Contrast sensitivity,
 Stereopsis
 Fixation stability

 Contraindicated when some form of foveal
function exists

Management …EV
 Discussion:
 After EV training, reading speed doubled with little
to no improvement in Visual Acuity.
 Reading speed is a better parameter than visual
acuity when reporting results of visual
rehabilitation because
 Reading is more demanding than identifying a few
optotypes on a visual acuity chart
A practicable approach to rehabilitating patients
with CF loss

Management
 Prism Therapy

Management

 Text Enhancement…

Management…Text
Enhancement
 Conclusion
 Boosting the contrast increases the perceptibility
of letters and therefore words, then reading gets
faster
 Increasing the size of character overcomes the
scotomatous region thus allowing the non-
macular area to fixate extrafoveally
 Increasing the luminance of the characters
allows for a better recognition.

Psychological/Psychosocial
problems in Retinal Dystrophy
 Fear of growing blind
 Fear of ostracism
 Impaired social life
 Susceptibility to harassment

Refer
Train
Treat
Low Vision Service

Eye Care Education

Detect Educate

Identification

VI Child

References:
 Tasca Jennifer, Edward A. Deglin. Chapter
SIX „Common Disorders Encountered in Low
Vision‟ in “ESSENTIALS of LOW VISION
PRACTICE”, 1ST Edition, BUTTERWORTH
HEIMAN,1999

 Kathleen Fraser Freeman, Cole Roy
Gordon, Eleanor E Faye, Paul B.
Freeman, Gregory L. Goodrich, Joan A.
Stelmack. Optometric Clinical Practice
Guideline Care of the Patient with Visual
Rehabilitation(Low Vision

References:
 Ferraro, J. and Jose, R. T. (1983). Training
programs for individuals with restricted
fields. In R.T. Jose (Ed.), Understanding
Low Vision, American Foundation for the
Blind, NewYork. Vol. 14, 363-376.

 Crossland, Michael D. Visual
rehabilitation of patients with macular
diseases, in Focus, The Royal College of
Ophthalmologists

References:
 Ajit Kumar Thakur, Purushottam
Joshi, Himal Kandel, Subash
Bhatta.Profile of low vision clinics in
eastern region of Nepal: A retrospective
study.British Journal of Visual Impairment
2011 29:215

 Elisabeth M. Fine, Eli Peli.Enhancement
of text for the Visually impaired.J. Opt.
Soc. Am. A 1995;12;1439-1447

References:
 Jae Hoon Jeong, Nam Ju Moon. A Study
of Eccentric Viewing for Low Vision
Rehabilitation. Korean J Ophthalmol
2011;25(6):409-416

 Berson EL, Mehaffey L III, Rabin AR. A
night vision device as an aid for patients
with retinitis pigmentosa. Arch Ophthalmol
1973;90:112–6.

References:
 William H. Ridder III, John B.
Slegfried.Chapter 16 „Clinical
Electrophysiology‟ in Borish‟s Clinical
Refraction, 2nd Edition, BUTTERWORTH
HEIMAN Elsevier,2006

AND YOU THINK YOU ARE HAVING A BAD DAY AT WORK !!

Although this looks like a picture taken from a Hollywood movie, it is in fact a real
photo,

taken near the South African coast during a military exercise by the British Navy.
It has been nominated by Geo as "THE photo of the year".

Retinal Dystrophies Guideline Outlines Low Vision Rehab Process

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