BB

1. VISUAL IMPAIRMENT
[LOW VISION
REHABILITATION]
- By
V
.ELAKYA
3-Jun-18 1

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INTRODUCTION
• Identify patients with visual impairment
• Evaluate visual functioning of a compromised visual system effectively
• Emphasize the need for comprehensive assessment of patients
• Maintain and improve the quality of eye and vision care
•Inform and educate other health care practitioners regarding the
availability of vision rehabilitation services
•Increase access for the evaluation of individuals, thereby improving
their quality of life.

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Statement of the Problem
Visual impairment is defined as a functional limitation
of the eye(s) or visual system and can manifest as;
• Reduced visual acuity
• Contrast Sensitivity
• Visual field loss
• Photophobia
• Diplopia

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AOA defines vision rehabilitation as:
Vision rehabilitation is the process of treatment and education that
helps individuals who are visually impaired to attain maximum
function
MAIN AIM OF VISION REHABILITATION IS TO PROVIDE,
Satisfying level of independence
Optimum quality of life

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DESCRIPTION AND CLASSIFICATION OF VISUAL
IMPAIRMENT
• WHO Classifies visual impairment
Impairment
Disability
Handicap

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Standard Definition of Visual Impairment
•WHO Classifies visual impairment based on visual acuity/visual
field limitation and defines blindness as profound impairment.
•National Eye Institute defines low vision as visual impairment
not correctable by standard glasses , contact lens , meditation or
surgery , that interferes with ability to perform activity.

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Epidemiology of Visual Impairment
1. Prevalence and Incidence
• Estimates the number of visually impaired persons vary,
depending upon the criteria.
2. Risk Factors
• Age-related macular degeneration
• Cataract
• Glaucoma
• Diabetic retinopathy.

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CARE PROCESS
Diagnosis of Visual Impairment
1.Patient History
Nature of Complaint
Visual and Ocular history
General health history
Family Ocular history
Medication usage and medication allergies

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2.Ocular Examination
A)Visual acuity
B)Refraction
C)Ocular motility and Binocular vision assessment
D)Visual field assessment
E)Ocular health assessment

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A. Visual acuity
Measuring visual acuity also allows the clinician to:
• Monitor stability or progression of disease
• Assess eccentric viewing posture and skills
• Assess scanning ability
• Assess patient motivation
• Teach basis concept and skills relevant to rehabilitation process
visual acuity testing :
It is the basis for determining initial magnification requirement &
best method to evaluate visually impaired patients.

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B.Refraction
Uncorrected refractive error is a significant cause of reduced visual
acuity
All visually impaired patients should undergo refraction for best
visual acuity
Uncorrected refractive errors affect success with low vision devices
Traditional procedures for assessment of refractive errors are less
effective
Radial retinoscopy can be performed

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C. Ocular motility and binocular vision assessment
Oculomotor system should be evaluated for ocular motility dysfunction
 Gross assessment of ocular alignment
 Sensorimotor testing
 Amsler grid testing, monocularly versus binocularly
 Contrast sensitivity testing

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D. Visual field assessment
Assessment of visual field includes,
• Confrontation visual field testing
• Amsler grid assessment
• Automated static perimetry
• Goldmann bowl perimetry or equivalent kinetic testing

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E. Ocular health assessment
Ocular health assessment includes:
External examination
Biomicroscopy
Tonometry
Central and peripheral fundus examination with dilation, unless
contraindicated
Standard slit lamp examination should also be performed

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3.Supplemental Testing
• Contrast sensitivity testing
• Glare testing
• Color vision testing
• Visually evoked potential (VEP)
• Electroretinogram (ERG)
• Electro-oculogram (EOG).

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Management of Visual Impairment
Goals which enhance patients quality of life :-
• Improving distance, intermediate, or near vision
• Improving print reading ability
• Improving the ability to travel independently
• Improving the ability to perform activities of daily living
• Maintaining independence
• Understanding the diagnosed vision condition.

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BASIS FOR TREATMENT
• Degree of visual impairment, disability, or handicap
• Underlying cause of visual impairment and prognosis
• Overall health status of the patient
•Other physical impairments which may affect the ability to participate
in vision rehabilitation
• Patient's adjustment to vision loss
• Patient's expectations and motivation
• Patient’s ability to participate in the rehabilitation process
• Visual requirements, goals, and objectives.

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AVAILABLE TREATMENT OPTIONS
A)Management strategy for reduce visual acuity
1.Magnification for near
I. Spectacle – Mounted Reading Lenses
II. Tele microscopes
III. Hand Magnifier
IV. Stand Magnifier
V. Electronic Devices

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1. Spectacle-mounted reading lenses
(Microscopes)
Advantages:
-provide wide field of view
-they are portable
-handsfree- not needing to hold a
magnifier
-with low power magnifying
reading glasses you may be able
to use both eyes
Disadvantages:
-they required to hold things very
close
-you need to hold print material
very steady
-challenges faced by patients is
adaptation to close working
distance.

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2. Telemicroscopes
Advantages:
• Provide comfortable working
distance
• They are used by patients who
are unable to adjust to closer
working distance
Disadvantages:
• They provide a smaller field of
view
• Patient need to hold the reading
material steady
• They feel heavy on your nose
and face
• They can be quite expensive

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3. Hand-held magnifier
Advantages:
They are portable
Afford magnification at variable
working distance
A shorter lens-to-eye distance
will allow greater field of view
Disadvantages :
They require steady hands and
good motor control
Magnifier doesn’t have built-in
light, so it may cause shadows
Patients feel very tiring to hold it

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4. Stand Magnifier
Advantages:
 They rest flat on the page and
don’t need to hold in the hand
 The focusing distance is set by
simply placing the magnifier on
the page
 It comes with built in light that
provides excellent illumination
 Fairly inexpensive and easy to
use
Disadvantages:
 Larger and bulkier
 They are not portable
 You may see a small field of
view, you have to bend-over to
read
 If the stand magnifier doesn’t
have built-in light, it may cast
shadow

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5. Electronic Devices
• CCTV’s and HMDS not only magnify image but enhance contrast
sensitivity
• Working distance and usable field of view can be varied
• CCTV provide comfortable reading/writing posture
• Newer, compact designs have been developed to address the
drawback i.e., lack of portability

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MAGNIFICATION FOR DISTANCE
In prescribing distance magnification devices certain,
consideration should be given to:
• Visual demands of the task
• Field of view
• Image brightness/contrast
• Hand held or spectacle/head mounted
• Binocularity
• Variable magnification

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Magnification for Distance
• Telescopes
- These devices can be prescribed as hand held or spectacle
mounted systems
spectacle mounted telescopes == full diameter
hand held telescopes == used for short term viewing/
spotting activities
- potential drawbacks of telescopes are weight factor &
alignment problems

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• Electronic Device
- several head mounted video devices or electronic magnification
systems are available
- These devices are useful for both distance & near applications
The selection of final distance magnification system can be
determined by no. of factors like
= ease of use
= requirement for hands free magnification
= requirement for mobility
= contrast or image brightness
= weight and cost
= cosmesis

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B)Mangement strategy for central visual field
defects:-
•Central visual field defects affect visual functioning
Management include :-
• Teaching awareness of the scotoma
• Teaching off-foveal viewing with guided practice techniques
• Reading single letters or words
• Reading with low magnification and large-print materials
• Moving the reading material rather than the eyes or head
• Using prism relocation

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C)Management Strategy for Peripheral visual
field defects
• Prisms:
used to shift the image towards the apex
• Mirrors:
can be angled towards the non seen area much like a side mirror
on a car
• Reverse Telescope and minus lens:
These devices minify the entire visual field

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D)Management strategy for reduce contrast
sensitivity and glare sensitivity
• Optimum lighting
• Increased magnification
• Use of specific lens designs
• Use of tints, filters, lens coatings, apertures, etc.
• Non-optical devices
• Electronic devices.

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E)Non optical devices
Recommendation for non-optical aids includes,
1. Large print materials;
2. Writing aids;
3. Reading stands;
4. Auditory aids;
5. Audio or taped materials;

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Training/Instruction Considerations
Practical training session should provide information about:
Name or category of device;
Advantage & disadvantage of device
Efficient use of devices;
Use of device for specific activities;
Care, cleaning & maintenance of optical system;
Safety;

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Training the use of residual Vision :
• Eccentric viewing;
• Scanning;
• Fixating;
• Pursuits;
• Blur interpretation, Memory & Word recognition.

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Additional services
• State blind rehabilitations
services;
• Occupational therapy;
• Counseling services;
• Technology evaluation for
computer software and
hardware;
• Talking books programs;
• Radio and reading services;
• Non visual approaches;
• Nutritional counseling;
• Additional medical/ ocular
services;

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Patient’s Education
• Review of visual & ocular health;
• Explaining available treatment options;
• Written information or instruction;
• Discussion of follow-up;
• Recommendation for re-examination;

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Prognosis & Follow-up
• Goal – patients, physical & mental ability;
• Number & frequency of follow-up visits depend on stability of eye
condition & response to therapy;
• Follow-up include ongoing assessment of eye health & vision status;
• Patient’s need and vision may change and it is important for re-
examination;

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Conclusion
• Visual impairment have significant impact on patients quality of life;
• It can affect ability to read, work & perform daily activities;
• There is a greater need for evaluation, management & rehabilitation
services;
• Comprehensive optometric low vision care improve quality of life for
visual impairment patient.

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REFERENCE:
AMERICAN OPTOMETRIC ASSOCIATION (2002)
CLINICAL PRACTICE GUIDE LINES.

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THANK YOU 