Visual Dysfunction
Loss of vision in peripheral areas horizontally, vertically or diagonally
field cut
The process of focusing whereby the lens changes curvature so that various viewing distances remain clear
accommodation
The foundation of visual skills
visual acuity, visual fields, oculomotor control
Directing the person's gaze to follow object in an H pattern to the extremes of gaze and then a large circle pattern
Smooth pursuits
Adapting the environment to improve lighting, create different colors and textures, remove complex patterns, magnification, and glare
environmental modifications for visual acuity impairments
A set of assessments that measure visual functions important in ensuring that visual perceptual processing is accurately completed
The Brain Injury Visual Assessment Battery for Adults
Problems seeing clearly either at a close or far distance relate to this aspect of vision
visual accuity
Small, precise eye jumps
saccades
Dysfunction of the higher level visual skills can be confused with
injury/disease to certain cortical areas
Ask the person to cover their left eye and then identify letters from a distance of 20-feet away beginning on the 20/40 line, continue until last line they can identify at least 50%
Distance visual acuity
Problems with visual acuity and prisms
When to refer client to opthamologist
Common measure of visual acuity
Snellen chart
Exhibits poor balance, walking next to walls, trouble seeing steps or curbs, shortened and uncertain stride, and trouble identifying visual landmards
Inferior field loss
When the eyes follow a moving stimulus
smooth pursuits
Moving objects towards eyes at midline and then away from eyes, measuring the point where they experience double vision and again at the point where vision returns to normal.
Near point of convergence
teach organized searching, anchoring, Dynavision, games, prisms
Interventions for field cut
It maps the available visual fields based on the person's ability to correctly press a buzzer when they see a light pop up in different parts of the field
perimetry
Symptoms of this diagnosis include convergence insufficiency, accommodative dysfunction, photophobia, and difficulty with fixation and pursuits
Post-traumatic vision syndrome
The ability to bring the eyes together smoothly and automatically along the midline to observe objects singly at near distance
convergence
A test card is held 16 inches from the person. The smallest size able to identify is recorded and they are allowed to wear corrective lenses if used
Near/reading acuity
Increasing awareness, using other senses, reducing clutter, and teaching safety strategies
Interventions for agnosia
Inability to recognize faces
prosopagnosia
Depth perception and its relationship to spatial judgement
Stereopsis
Hold a stick with 20/30 letter/symbol 1 inch away from right eye while left eye is occluded and then pull away until the person is able to identify the letter/symbol
Accommodation
Require supervision by an eye care specialist, visual exercises, patching, and prisms are used for this
oculomotor control deficit
visual loss congruency, abruptness of boundary, presence of macular sparing, client awareness
Factors of impact to field deficit
lateral rectus, superior rectus, inferior rectus, medial rectus, superior oblique, and inferior oblique
muscles responsible for eye movement
Direct person to look back and forth between two different colored objects 5 times or 10 fixations
Testing saccades
Can lead to quadrantanopsia or hemianopsia, may have macular sparing, often homonymous
Field deficit after ABI
When the eyes have trouble moving together
Dysconjugate gaze
Occlude one eye and then slowly introduce your hand from behind a person's head while wiggling two fingers into different parts of the visual field
Visual fields: confrontation test