Visual Dysfunction in Neurological Rehabilitation

Initial processing of visual-spatial information is processed in the…

right hemisphere

Detail of visual-spatial information is processed in the…

left hemisphere

Function of frontal lobe relating to vision

Voluntary eye movements

Function of parietal lobe related to vision

Distinguishing size, shape, and color; spatial perception, visual perception

Unilateral parietal lobe dysfunction

sensory deficits, motor deficits, visual disorders, contralateral neglect, constructional and dressing apraxia

Dominant parietal lobe dysfunction

language disorders, gertsmann syndrome, apraxia

Non-dominant parietal lobe dysfunction

hemispatial neglect, sensory and visual inattention, constructional and dressing apraxia

Bilateral parietal lobe dysfunction

visuospatial, balint syndromq

Function of occipital lobe

visual reception, synthesis and integration visual info, perception visuospatial relationships

Damage to occipital lobes

visual impairment, blurring or blind spots, visual hallucinations, difficulty reading and writing

visual impairments

• visual acuity and accommodation

• visual fields

• oculomotor

  • vergence

visual acuity and accomodation deficits

blurred vision, visual fatigue, poor concentration

Visual field deficits

homonymous hemianopia

Oculomotor deficits

excessive head movement, poor attention, slow tracking, skipping when reading, may complain of headaches

vergence deficits

difficulty focusing, depth perception, spatial judgment, eye hand coordination

strabismus

esotropia, exotropia, hyperopia, hypopia, double vision, decreased coordination

functional scanning

omitting words or letters, exaggerated head movement, losing place, using finger to follow

color perception deficits

faded colors, difficulty distinguishing colors

stereopsis

difficulty depth perceptions, spatial judgement, and 3D

Warren’s Visual hierarchy

Vision and cognition are interconnected

What are three base levels of Warren’s Hierarchy?

Oculomotor, visual fields, visual acuity

What are some visual screening assessments and tools?

Observatiom, visual pursuit, reading screen, visual search strategies, design copy, confrontation field testing, line bisection, BiVABA

Brain Injury Visual Assessment Battery for Adults

Focused on functional visual components: visual acuity, oculomotor function, visual fields, contrast sensitivity, and visual inattention

Form constancy

the ability to recognize and label an object even when they are viewed from a different angle or position

Screening procedure for form constancy

• client situated in well-lit area

• lay kitchen utensils on counter

• client identifies utensils on display

• OT observes for spatial neglect, perseveration, poor scanning patterns, and comprehension

Impact of deficits in form constancy

difficulties with reading, writing, navigating, and locating items within personal environments

Figure ground perception

ability to distinguish a foreground figure from the background

screening procedures for figure ground perception

• client locates specific coins from coin array

• locate school items in pencil box

• identify road signs along busy streetscape

• observe for poor acuity, spatial neglect, preservation, poor scanning patterns, agnosia, and comprehension

Figure ground perception impact on daily functioning

difficulties identifying objects from busy or similar backgrounds

visual closure

ability to visualize a complete whole when provided with fragmented pictures or incomplete information

Screening procedures for visual closure

•Client completes a partially drawn picture, or identifies whole image from a partially drawn form

•Correctly identifies 10 common objects from array of 30 overlapping items

•Write/draw image on dry erase board – client identifies word or image

Impact of visual closure deficits

Those with decreased visual closure encounter difficulties with learning tasks, handwriting, home management, etc.

When items are partially occluded within the visual field, accurate identification of objects is difficult. 

Visual organization

property of visual perception form discrimination 

Screening procedures for visual organization

Using technology, primary goal is quick screen for possible mid-level visual perceptual deficits

Visual organization deficits impact on daily function

Decreased visual organization creates difficulties in making sense of the extrapersonal and intrapersonal visual environments.

Deficits create increased difficulties with figure ground perception and visuoconstructional skills.

Spatial orientation

ability to appreciate the location of objects as related to each other and to oneself.

Screening procedures for spatial orientation

•Provide client with card with cross markings

•Client reproduces crosses on blank card—accurately as possible

•OT provides feedback noting disparities

•Client completes with additional cards and crosses

•Score measured in cm of discrepancy between model & client reproduction

Spatial orientation deficits impact on daily function

Visual-spatial deficits create functional difficulties in general awareness of oneself and of objects in the interpersonal and extrapersonal environments

This presents as difficulties with basic self-care 

Depth perception

visual perception using binocular cues and disparity with monocular cues (e.g., shading).

Screening procedures for depth perception

Two screens detect deficits in stereopsis—Lang Stereo Test I and the Titmus Test.

Depth perception deficits impact on daily function

Assessing depth perception through binocular or monocular cues—imperative for safety.

Low depth perception is frustrating (e.g., dressing and hygiene)

Compensations for depth perception

Environmental contextual cues, interpreting visual illusions and monocular cues

Intervention for oculomotor deficits - diplopia

Patching one eye or partial visual occlusion, prism glasses, vision therapy/eye exercises

Interventions for acuity

Increase illumination, increase contrast, decrease background pattern, decrease clutter and organize the environment, increase size

What is the incidence of hemianopsia with a stroke?

30% of clients

Interventions for scanning

Rotation activities, scanning while static, scanning while mobile, scanning newspaper ads, sorting items, specific reading, writing, and mathematical calculations training

Compensations for scanning

• Visual scanning training

• paper-and pencil tasks, computer activities

• vision coach training

Unilateral inattention

decreased awareness of the body and spatial environment on the side contralateral to the brain lesion 

Screening procedures for unilateral inattention

Commonly used screens in practice are the Bell’s Test, Clock Drawing Test, Single Letter Cancellation Test & others 

Impact of unilateral inattention deficits

Impact difficulties range from reading to missing information while driving or walking in parking lot

Visual inattention

occurs with right hemisphere damage, does not have awareness of deficit, disorganized scanning patterns

Visual field

common with PCA lesions, retains awareness

Interventions for unilateral inattention

prisms, attention training, scrolling text, audiovisual stimulation, video feedback training, learning new scanning patterns, and lighthouse scanning to affected side

Effective intervention principles

1) Remove or minimize sensory deficits of foundational skills

2) Provide education to increase awareness of deficits

3) Incorporate consistent training to remediate and develop compensation strategies

What are some general strategies for interventions?

• Discuss the purpose and results of activity w/ client

• behavior modifications → “do this, not that”

• use functional tasks

• use individuals’ routine and habits

• practice activities in appropriate environment

• vanishing cues

• graded assistance

Adapt task or adaptive equipment strategies

• turn written work sideways and read up and down

• use anchoring technique

• position objects and people on affected side to necessitate client turning

• use of prism glasses shift image

What can an OT do if they have client’s who do not response to strategies or recover?

Environmental adaptation such as placing food in preferred visual field, using colored cues.

Visuospatial

process needed to identify, integrate, and analyze space, visual forms, structure, and spatial relations in more than one dimension

temporal lobe

interprets visual meaning and object recognition

parietal lobe

spatial navigation

prefrontal lobe

visual perception and decision making, assists in processing information and allow adaptation to the environment

brainstem

responsible for pupillary responses and reflexes working in conjunction with the cerebellum for control of eye movements and coordination of the entire visual system

visuo-spatial impairments

• stereopsis

• spatial relations

• right/left discrimination

• topographic orientation

• figure ground discrimination

Symptoms of visuospatial deficits

• confusion related to space and objects

• difficulty reaching accurately for objects

• difficulty determining what body mechanics to use to transfer

• feeing unsafe

• familiar objects now being unfamiliar

• difficulty finding everyday objects

• difficulty with mobility

Intervention for spatial positioning/relations

• increase client’s awareness of impairment

• compensation strategies

• provide models for language

• practice following right/left directions using body and environmental space

Interventions for figure ground discrimination

• teach awareness of deficit

• teach organization skills

• slow down to identify all details of object

• use contrasts between foreground objects and background

  • task practice

Interventions for topographical disorientation

• mazes simple to complex

• colored dots to mark the route

• with mastery, take away cues

Interventions agnosia

increase awareness, compensation to use alternative intact senses to recognize objects