Transcript LOW VISION
LET’S TALK
LOW VISION
Suleiman Alibhai, O.D.
Retina Group of Washington
Krista M. Davis, O.D., F.A.A.O.
Columbia Lighthouse for the Blind
Eye Anatomy
Definitions
Legal Blindness
– Best corrected distance visual acuity of 20/200 or
worse in better eye
– Horizontal visual field of 20 degrees or less at widest
point in the better eye
Low Vision
– Worse than 20/60 in the better eye
– Significant field loss
– Impaired function
Goals of Low Vision
Management
Increase functionality
– Make the most of the remaining
vision
Provide link to community
resources and support services
Education
Common Conditions
Macular Degeneration
Albinism
Glaucoma
Nystagmus
Diabetic Retinopathy
Cortical Visual
Impairment
Stroke/ brain injury
Retinitis pigmentosa
Optic Nerve disease
Functional Effects of
Low Vision
Loss of central vision (visual
acuity)
Loss of peripheral vision
(visual field)
Glare and contrast
Issues Related to
Decreased Acuity
Difficulty reading
Problems writing/ completing
paperwork
Inability to recognize
distance objects and faces
Issues Related to
Visual Field Loss
Location of scotoma important!
Generalized loss of visual field
difficult to compensate for
Mobility and independent travel
Reading may require adaptations
Issues Related to Contrast
Need for additional lighting
Problems with glare
Increased adjustment to changes in
illumination
Visual discomfort and fatigue
Exam Sequence
History/ intake
Visual acuity
Visual field testing
Pupils
Extraocular muscle testing
Refraction
Color vision and Contrast Testing
Ocular Health
Types of Acuity Charts
Distance
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Snellen (projection)
Feinbloom/ SOSH
ETDRS
Lea Symbols
Near
– Single letter
– Continuous text
Distance Charts
Near Charts
Interpreting Near Acuity
Threshold acuity
– Difference between single letter and continuous
text
1.0 M = 20/50 = 8-10 point font
– Need to look at working distance
– Jaeger charts nonstandard
Typical sizes
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Newspaper = 1.0M
Children’s books = 1.2 – 1.6M
Large print = 1.6 – 2.0M
Newspaper headlines = 4.0 – 5.0 M
Visual Field Testing
Confrontation
Arc perimeter
Vision Disc
Automated perimetry
Goldmann perimetry
Color and Contrast Tests
Ishihara
Color Vision Testing Made Easy
D-15
Pelli-Robson
Vistech Contrast System
Mr. Happy
Hiding Heidi
Color Vision Tests
Contrast Tests
Magnification
Enlarges image on retina to stimulate more
retinal cells
Can be achieved in many ways
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Relative Distance
Relative Size
Optical / Angular
Electronic
Low Vision Devices
Distance
Near
Field enhancement
Non-optical
Distance Devices
Hand held telescopes
Mounted telescopes
Electronic systems
Telescopes
Electronic Distance Systems
Near Devices
Spectacles
– Prismatic ½ eyes
– Full-field microscopes
Magnifiers
– Hand held vs. stand
– Illuminated vs. non-illuminated
Telemicroscopes
Electronic Devices
Spectacle Microscope
Near Loupe
Hand Held Magnifiers
Stand Magnifiers
Electronic Magnifiers
Non-optical Devices
Glare reduction devices
Contrast enhancement devices
Computer software
Accessory devices
– Talking watches, clocks, etc
– Writing guides
– Tactile markers
Glare and Contrast
Lighting
Other Non-optical Devices
Adaptive Computer
Equipment
Additional Services
Orientation and mobility training
Independent living skills training
Support groups
Braille instruction
Computer training
Genetic counseling
Community Resources
Support groups
Paratransit Services
Books on tape
Audio described performances
Tactile tours
Large print publications
Educational services
Communication Goals
Educate patient on eye condition
Help them to understand what options are
available and how to use/ care for tools
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Glasses
Low vision devices
Technology
Community resources
Educate parents and teachers/ professionals on
functional implications
Functional Implications
Print size
Visual efficiency and fatigue
Mobility issues
Positioning/ classroom placement
Lighting/ glare reduction needs