1 Implementing Low Vision Rehab Assessment Intervention Planning
Dec 16, 2015
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Implementing Low Vision Rehab
Assessment
Intervention Planning
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Steps to Successful Intervention
Identify the limitations the client is experiencing in daily occupations
Determine how well the client is able to use remaining vision
Design treatment intervention– Increase the visibility of the environment– Enable the client to use remaining vision
more effectively
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Client’s ability to use remaining vision Four key visual functions
– Acuity– Contrast sensitivity– Visual field– Color vision
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Acuity Measured using low
vision test chart– Measures acuity from
20/20-20/1000– Provides visual
impairment level– Provides a rough
estimate of the strength of the magnifier
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Eye Dominance Test Materials
– Card with 8mm hole– Target
Important to know because it explains challenges in using magnifiers and remaining vision
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Reading Acuity
Best chart is MNread acuity
Combination reading acuity and reading performance test
Measures reading acuity to 20/400
Also measures reading speed and critical print size
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Contrast Sensitivity Function (CSF)
Ability to see image as it degrades in contrast from its background
Important to know because most environment features are low contrast
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Can you see the water on the floor?
Reduction in CSF
Client will have difficulty detecting low contrast features– Water spilled on a floor– Gray cars moving
against a gray background
– Facial features– A glass filled with water– Filling a glass with water
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Scotoma and PRL Location
Instruct client to look at center of the target and without moving his/her eye and tell you if certain areas of the target look blurry, faded, distorted or missing
Note the location of the blurred or missing vision– Indicates location of scotoma
Repeat-having client look off center to see if blurry area clears up– Indicates location of the PRL
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Ability to use PRL
Locate Track Gaze Shift
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Color Vision
Changes in color vision are largely caused by impairment of cone function– Always occurs to some extent with macular
diseases Also occurs as a by-product of aging
– Yellowing lens restricts short wave length color
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Visual Skills for Reading Test(aka the Pepper test)
•Assesses visual decoding components of reading•Determines whether the scotoma interferes with reading
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Additional Information
Dark/light adaptation Glare sensitivity Phantom vision
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Intervention
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Self Report Interview Format is Optimal Self report gives person chance to
establish priorities Observation of a few key activities is
necessary to confirm report– Some clients over or under estimate
abilities
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Treatment Approach
Maximize use of current visual ability– Teach person to use remaining vision more
effectively– Modify environment to increase visibility to
enable client to use remaining vision
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Develop Ability to Use PRL
Establish efficiency of PRL as the new locus for spatial orientation
Accomplished by presenting tasks that require proficiency using PRL – Challenging visual system/CNS to adapt
Rationale:– Research shows poor control of gaze or unstable fixation
contributes to the significantly lower reading rates observed in persons with macular scotomas
– Proficiency using PRL is more predictive of reading ability than acuity
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Training PRL Practice with Clock Locating, tracking,
gaze shift Pre-reading
exercises
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Magnify
Magnifier is not a magic pill but just a piece of adaptive equipment
Changes with magnification– Reduced viewing field– Shortened focal distance– Monocular use of eye
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Basic Technique: Stand Magnifier Lay the magnifier on the reading material View using the reading add of the bifocal Pull the magnifier across the line of print To move to the next line of print
– Return the magnifier to the left side by pulling it back over the line of print just read
– Move the magnifier down to the next line
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Basic TechniqueHand Held Magnifier Begin by laying magnifier on the page and
pulling it away until the print comes into focus View using distance portion of the eyeglasses Two techniques for reading
– Hold the text steady and move the magnifier or– Hold the magnifier steady and move the reading
material
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Move-the-Magnifier Reading Technique Hold the reading material steady Move the magnifier across the page Return to the left side by moving the
magnifier back over the line just read Move the magnifier down to the next
line
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Move-the-Reading-Material Technique Hold the magnifier steady Move the reading material under the
magnifier Return to the left side by moving the
reading material back under the magnifier over the line of print just read
Move the reading material to the next line
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Basic TechniqueMicroscopes (Spectacles) Have the client locate the focal point by
holding his/her hand up to the lens then moving it away until it comes into focus– Place the reading material there
Can use either technique of moving the reading material or moving the magnifier
Be sure the page is evenly illuminated at all times
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Basic Technique: CCTV
Be sure the client understands how the CCTV works– Location of the camera– Size and focus controls– Polarity– Operation of X-Y table
Demonstrate each function and have the client practice
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Basic Technique: CCTV
Determine the smallest size print the client can see by starting at maximum magnification and gradually decreasing the size– Want smallest print possible to maximize
the number of characters on the screen Find the area of the screen that the
client can see best
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Basic Technique: CCTV
Break the task into small learning components– Start by moving the XY table for the client
while the client concentrates on reading– Introduce operation of XY table by placing
your hands on client’s hands and moving the table
– After practice, remove your hands and have the client operate the table alone
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Same reading technique is taught– Move the table to move the line of print
across the screen– Return to the left side by returning over the
same line of text before dropping down to the next line
Outline columns with a marker to help the client keep his/her place
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Handwriting Technique with the CCTV Reduce the level of magnification Have the client hold the pen and move
the hand in until he/she can see the pentip
Watch the screen when writing
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Basic Instruction Principles
Avoid fatigue and stress– Observe client very carefully– First treatment sessions should be short
Ensure successful performance– Break the task down– Use good quality reading materials
• Sans serif font, spaced text, simple
– Use reading materials client will enjoy
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Control lighting– Good ambient lighting will reduce eye
strain– Reading materials should be well
illuminated (no glare) Make sure client is using good
ergonomics
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Increase Visibility of the Task
Ensure lighting is optimal for task performance
Use contrast to increase visibility of key objects and landmarks
Minimize background pattern Magnify and enlarge Organize
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Lighting
Persons withmacular diseaseperform better
with additional
lightbecause it
allowsuse of relativescotomas Orange areas (threshold scotomas
can still function with good illuminationdecreasing the size of the scotoma
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Desired Light Qualities
Even illumination– No surface shadow
Maximum lumens Minimum glare Flexible placement
– To get optimum positioning
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Address both room and task lighting– Room lighting
• Overhead light fixtures, floor and table lamps, windows
– Task lighting• Reading lamps, flashlights etc.
Determine the type of lighting that works best– Incandescent– Fluorescent– Halogen– Full spectrum
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Use Contrast to Increase Visibility of Key Components of Task Items
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Minimize Background Pattern
Like static on a radio, makes it more difficult to locate item needed
Use solid colors on background and support surfaces
Eliminate clutter When you can’t eliminate pattern,
increase contrast of key structures
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Use solid color for background surfaces
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Reduce and Eliminate Clutter
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Enlarge
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Organize
No organization Items grouped by typeon separate shelves;handles marked withcontrasting tape
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Enhance Visual Components/ Augment with Other Sensory Input
Use various materials to mark features of objects
to increase their visibility or allow another sensory system to identify them
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1. Colored plastic tape2. Tactile adhesive dots3. Black marking pen4. Hi marks-tactual marking substance
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Example of Combination of Visual and Tactual Marking
Microwave key pad marked with hi marks
Door opener marked with black velcro dot
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Modify the Environment
Eliminate clutter Store items only 1 row deep and unstacked Create work centers
– Store items used for similar purposes together
Locate items close to where they are used Make use of commercially available systems
to organize closets, drawers etc.
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Modify the Task
Simplify– Eliminate tasks– Reduce visual steps
Reinforce routine– Nailcare– Medications– cleaning