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25 Cards in this Set
- Front
- Back
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Low vision definition
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Visual impairment severe enough to interfere with performance of daily activities but allowing some usable vision
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According to the ICD-9,
Moderate to severe visual impairment ranges from...? |
20/70-20/400
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According to the WHO,
Low vision is when the better eye with best correction is...? |
20/60
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Visual acuity of 20/12-20/25 is _______level of visual impairment?
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Normal
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Visual acuity of 20/30-20/60 is ________ level of visual impairment
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Near normal
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Visual acuity of 20/80-20/160 is _______level of visual impairment
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Moderate
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Visual acuity of 20/200-20/400 is ________level of visual impairment
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Severe
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Visual acuity of 20/500-20/1000 is ________level of visual impairment
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Profound
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Visual acuity of 20/1250-20/2500 is ________level of visual impairment
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Near blindness
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Visual acuity of >20/2501 is ________level of visual impairment
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Blindness (no perception of light)
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_________affects central vision, has wet and dry forms, 90% of people have dry form
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Macular degeneration
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___________is due to intraocular pressure, aqueous build up, optic nerve compression.
_______also impairs peripheral vision, causing scotomas |
Glaucoma
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________causes cloudiness or opacification of the lens
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Cataracts
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Age related changes that affect the amount of light that reaches the retina
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Reduction of pupil size
Pupil dilation decrease Aging lens and cornea causes light to scatter and glare intolerance Slowing of dark adaptation |
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Other age related changes that affect vision
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Loss of visual accommodation
Decreases in VA, CS, VF, and color perception Floaters, dry eyes |
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What population/age group will have more difficulty with daily activities?
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People over 65 years old with visual impairment
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National Blindness System
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Network of state, federal, educational and private agencies
Primary emphasis on vocational rehab |
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Health Care System
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Services provided in hospitals, rehab and occupational performance facilities with emphasis on older adults
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Preferred Retinal Locus (PRL) Assessment
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Good indicator for rehab potential
2 components: Awareness and influence of macular scotoma on visual performance Ability to compensate for macular scotoma by using PRL |
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OT intervention lighting principles
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Ensure even lighting
Eliminate direct and reflected glare Use multidrectional light sources Coated incandescent bulbs (preferred_; halogen is still a good option Direct task lighting , avoid direct lighting toward eyes Reading: direct light over shoulder of strongest eye Writing: situate light opposite their dominant hand Move light closer Increase wattage: 50 for task, 100 for room Use shades that allow light to pass through, use lamps and overhead fixtures |
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Training in the use of Preferred Retinal Locus (PRL) training
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Key for individuals with central vision loss
Provides indication of client's rehab potential for reading and use of vision Visual system adopts the use of eccentric retinal areas PRL position(s) varies with each individual |
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Preferred Retinal Locus training addresses
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Awareness of scotoma
Client's ability to locate the PRL (using gaze shift) Ability to use PRL to direct eye movements (locate, fixate, gaze shift/saccades, track target) Ability to use PRL to direct hand movements |
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Assessing reading performance
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Background information
Determine eye dominance Determine if scotomas interfere and use of PRL |
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Intervention for reading performance
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Practice use of PRL without magnifier
Pre-reading exercises Introduce reading text - start with simple text with large/high contrast then progress - increase text visibility Introduce magnification using dominant eye after visual skills are developed |
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Drawbacks of using magnification as a reading compensatory strategy
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Reduce viewing field
Shortened focal length Some require monocular use of eye |
