Vision Flashcards
optic disc
Blind spot
Fovea
light sensitive inner lining of the eye (sends electrical signals to the brain to stimulate visual recognition. (greatest ability to process detail)
Macula
Inside the fovea- the spot where vision is the most highly developed
impaired by CVA
if one ocular muscle is unable to focus eye, it creates double image
Vision
Primary sensory system used to acquire information about the environment. the most complex system (furthest reaching sense). the fastest sensory system.
Optical system- ability to see objects
Cortical system- ability to interpret what is being seen
Visual processing
allows us to anticipate information necessary for successful adaptation to the environment
Focal- attentive vision (what you focus on)
Ambient- peripheral vision
information processing
Need a clear optical image- optical input
Integration- sensory information is blended and results in plan which guides response. information blended into thought, recognize objects
Output- Ocular-motor response (guides behavior, eye hand coordination and commuting mobility)
Visual perceptual hierarchy of skills
- Oculomotor control, visual fields, and visual acuity
- Attention (alert and attending)
- Scanning
- Pattern recognition
- Visual memory (try and make a picture out of object we just saw)
- Visuocognition
- adaptation through vision (what is our response)
Pattern recognition
The ability to identify the holistic aspects of an object: to see its general shape, contour, and features.
ability to identify features of an object and use features to distinguish the object from its surroundings.
Visual memory
the ability to create and maintain a picture of an object in the minds eye. Keeping and storing an image and calling it up at a later date.
Must be able to store and recall from ST and LT memory.
visuocognition
the ability to manipulate visual information mentally and integrate it with other sensory information to gain knowledge and to solve problems, formulate plans, and make decisions.
foundation for reading, writing, math, etc…
cannot occur without the presence of visual memory.
neurologic dysfunction
Focal system is compromised.
Integration is disrupted:
-between focal and ambient systems
-between visual system and other sensory inputs.
Can disrupt visual processing at any level in the hierarchy
Glaucoma
the mechanical compression and or decreased blood flow of the optic nerve and nerve damage and visual loss can occur.
Leading cause of blindness throughout the world.
Macular degeneration
Destroys the macula. Where vision is most highly developed. results in impairment in our central vision. Causes blindness and only focuses on central vision.
Retinopathy
blood vessels in retina, untreated can lead to blindness. Treatment is laser therapy or medication
Cataracts
small splotches, easy to take care of. (cloudiness of the lends and impairs vision)
readiness for evaluation
- time of day
- room illumination
- corrective lenses during testing
- positioning (sees better sitting or standing)
- ability to communicate
OT vision assessment
- Visual acuity
- Visual field loss
- Oculomotor impairment
- attention (visual attention)
Visual acuity
clarity of vision- prerequisite for rest of visual system.
- CNS processing records 4 primary spatial components:
- frequency (what are we looking at)
- Orientation (vertical, horizontal)
- Contrast (what separates it from the ground or background)
- Intensity (the deepness of color)
focusing problems are fairly common.
Deficits in acuity (myopia, presbyopia, hyperopia, astigmatism)
Controlled by CN III (oculomotor)
Myopia
Nearsightedness (located in front of retina instead of on it)
Presbyopia
Farsightedness (hardening of the lens)
Hyperopia
Farsightedness (eye is too short from front to back, image behind retina instead of on it
Astigmatism
Unequal curvature of one or more of the refractive surfaces of the eye (the cornea) blurry vision. prevents light rays from focusing clearly on one place.
Vergence system
aligns eyes to maintain binocular fixation and binocular vision.
visual acuity eval
blurriness, Unable to read near and far, Need increased light, Running into things, Difficulty recognizing faces, Difficulty distinguishing colors
Contrast sensitivity
Contributes to CNS ability to detect and recognize objects and faces
interventions for acuity
- increase background contrast
- Increase illumination
- Reduction in background patterns
- Enlargement of objects or features that need to be seen
- Organization
- Access to community services
Visual fields
register the visual scene and ensure that the CNS receives complete visual information.
Perceptual completion
the brain fills in the blanks. The individual is totally unaware of the deficit. Nervous system completes the scene it expects to see.
Visual field eval
- bumps into objects
- misses visual detail on blind side
- difficulty locating objects on blind side
- anxious in dynamic environments
- difficulty with reading
- Face recognition
- Driving
- ADLs
Confrontation testing
hold number in one of the 4 quadrants, go into each of the quadrants and repeat what number they see you holding up.
VSRT
assesses reading speed and errors.
visual field treatment
education of the patient regarding the nature of his or her vision loss and the resulting functional limitations
Patient and family education
Active and passive approach
use head movements to try and overcome vision difficulties
active approach
more aggressive- work on education component to make sure everyone is on the same page.
increased head and eye movement (teach effective search patterns)
teach organized/efficient search patterns
BITS system- has all shapes transposed on a tv and shows a scan pattern.
Narrated walk- describe landmarks, reading signs
Community mobility
Scan boards
Peg boards
Beading
passive approach to VFD
- modify environment-reduce clutter
- decrease pattern in floor
- increase contrast
- increase illumination
Oculomotor control
ensures that eye movements are completed quickly and accurately. It allows our world to be stable.
Oculomotor dysfunction- issues with smooth pursuits, tracking, and convergence and divergence.
Goal: to maintain clearest vision (foveation)
oculomotor eval
- moving head side to side
- eye strain
- headaches
- visual acuity will be decreased
- fatigue (squinting all day)
- diplopia
- trouble with reading tasks
- poor eye hand coordination
are pupils symmetrical, are eyelids even, droop, corneal reflections the same?
symptoms of CN 3, 4, and 6
cant maintain a central position of the eye socket
Diplopia
eye drifts in and out
(may not move together in synergy)
Saccadic eye movements
brief moment where eye is stationary. As eye tracks stimulus from one side to another the eye will just stop and then tries to catch up. can be in one or both eyes (one is more common)
oculomotor impairment
Adult acquired paralytic strabismus:
misalignment of eyes due to paralysis or weakness of one or more muscles
Most common oculomotor impairment following TBI
Phoria
weakness of muscle.
Eye would drift but held in check by sensory fusion. As long as focusing on target eyes will be in alignment.
known as lazy eye
Tropia
Paralysis of muscle
Eye drifts even when person focusing on a target.
Esotropia
inward (cross eyes)
Exotropia
Eyes deviate outward (wall eye)
Hypertropia
Deviates upward
Hypotropia
Deviates downward
oculomotor intervention
a lot of times it will clear up after 6 months.
not in our scope to treat phorias or tropias. Our focus is on helping manage diplopia
Manage diplopia
Occlusion (cover)
- Total (pirate patch)
- Partial (transpore tape applied to nasal part of lens. allows for peripheral vision and sensory input)
Prisms-refer to optometrist (helps with light refraction)
Visual attention eval
clinical observation
Different search strategies from visual field deficits
- decreased attention to detail
- search strategies are quick and irregular
treatment of inattention
- patient and family education
- teach organized scanning strategies
- incorporate with motor feedback
- emphasize attention to detail
- compensatory strategies
- -reduce pattern
- -appropriate illumination
- increase contrast in the environment
