1 Implementing Low Vision Rehab Assessment Intervention Planning

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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