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585-10
Vision & Perception
Term | Definition |
---|---|
visual skills pyramid | Adaptation through vision (top) Visual perception Visual memory Pattern recognition Scanning Attention, alert, attending Oculomotor control, visual fields, visual acuity (bottom) |
retina vs. optic disk | Where neural synapses happen Contains photoreceptors vs. Blind spot |
cones vs. rods | Day vision, color vision, high visual acuity, ~5 million, dense in fovea vs. Night vision, no color, low visual acuity, not in fovea, ~100 million |
mesopic vision vs. color blindness | Uses combo of rods & cones vs. Loss/ abnormality in genes for cone pigments |
stationary night blindness vs. retinitis pigmentosa | Poor night/ dim light vision due to impaired rod function vs. Progressive degeneration of retina that leads to blindness |
damage to eyes can create | AMD Diabetic retinopathy Galucoma Metamorphopsia |
brain lesions may cause | Diplopia- damage to nerve controlling eye movement Oculomotor dysfunction Visual field deficits |
age related macular degeneration (AMD) | Degeneration at retina-choroid interface in macula Leading cause of blindness, bilateral, 65-70yr Decreased central vision, peripheral spared Need aids & training |
diabetic retinopathy | Damage to blood vessels in retina Central retinal artery swells & bleed Uncontrolled blood sugar is high risk Irreversible, slowed with medical management |
glaucoma | Decrease peripheral vision, tunnel vision Due to intraocular pressure that damages optic nerve Irreversible Injury, infection, blockage, inflammation is risk |
improving ADL functions with VI secondary to mechanical causes | Understand what they see & any distress Driving safety Assess fall risk Balance training Assess important task performance Implement compensatory strategies (contrast) |
tx for mechanical causes | Medication- eye drops for glaucoma, monitor pressure Nutrition- for AMD Laser Surgery Compensatory techniques |
binocular vision disorders vs. binocular vision disorders lead to | Nystagmus Strabismus Amblyopia vs. Poor depth perception, headaches, eye strain, fatigue, clumsy |
1. nystagmus 2. strabismus 3. amblyopia | 1. Uncontrolled repetitive mvmnt 2. Ocular misalignment, leads to development of amblyopia 3. Poor visual acuity in one eye, lazy eye |
affected eye movements vs. diplopia | Convergence/ divergence, saccades, smooth pursuits vs. Convergence insufficiency, one or both eyes, horizontal;/ vertical/ diagonal. Results from ocular misalignment |
tx for oculomotor impairment | Identify affected ADLs Retraining of oculomotor skills- saccades, pursuits, vergence Env modifications- clutter, environment Occlusion- partial, binasal Orthoptics- prisms, vision therapy Surgical intervention |
severed... 1. optic nerve 2. optic chiasm 3. optic tract 4. lateral geniculate body 5. optic radiation | 1. monocular visual loss 2. bilateral hemianopia 3. contralateral homonymous hemianopia 4. contralateral superior quadrantanopia 5. contralateral inf quadrantanopia |
functional deficits after visual field defect | Impaired insight Affects IADLs Losing items, tripping, walking into stuff, diff functioning, reading Driving cessation |
assessing visual field defects | Bedside screening Low tech perimetry device (biVABA) High tech perimetry device (Humphrey & Goldman), gold standard |
visual field defect intervention | Dependent on insight Vision loss doesn't return Compensatory retraining in field loss Compensatory strategies- scanning, env modifications, reinforce safety |
return to driving after visual field defect | In AB, you are required to self report changes in health that affects ability to drive safely 120deg of cont vision along horizontal 15deg continuous vision above & below fixation Both eyes opened & examined together |
low level vs. intermediate level processing | Orientation, color, contrast, disparity, mvmnt direction vs. Contour integration, surface properties, shape discrimination, surface depth, surface segmentation, object motion |
components of visual perception | Visual discrimination Form constancy Figure/ ground Closure Memory Visual-spatial relationships Object identification Spatial skills |
high level perceptual processing issues | Constructional abilities Visual agnosia- can't recognize visual objects Hemi inattention |
constructional ability | Needs right-left discrimination, visual discrimination, image rotation, visual memory, visual closure, form constancy, visual-motor integration, spatial relations 2D & 3D IADL considerations |
apperceptive agnosia vs. associative agnosia | Difficulty perceiving object as whole but can identify it vs. Can perceive object but can't identify what the object is |
prosopagnosia vs. alexia | Unable to recognize & identify familiar faces Unable to interpret facial expressions Occurs in fusiform face area vs. Inability to read |
1. simultanagnosia 2. dyscalculia 3. dysgraphia | 1. Unable to recognize/ interpret visual scene as whole 2. Difficulty recognizing numbers & perform basic math tasks 3. Difficulty writing letters and words |
assessment of agnosia | Use normal env to screen for basic visual perceptual deficits (use blank wall) Functional observation of functional tasks Components of standardized & informal ax |
tx for agnosia | Remediation Functional skills training Compensation/ adaptive |
remediation for agnosia vs. functional skills training for agnosia | Reps Computer programs Limited evidence, poor generalization vs. Naming, locating, identify objects Incorporate into daily routines |
compensation/ adaptive for agnosia | Environmental adaptations Use multi-senses Fixed location for frequently used objects |
hemi spatial neglect | Failure to detect & respond to stimuli presented to side opposite to brain lesion Mostly in right hemisphere damage (MCA stroke) Can be combined with visual field deficit |
personal neglect vs. peripersonal neglect | Lack of awareness of side of body opposite to site of lesion. Can be visual, auditory, tactile vs. Lack of awareness for side opposite the lesion but within arms length |
extrapersonal neglect | Lack of awareness for environment outside of personal space that's opposite of lesion |
allocentric vs. egocentric neglect | Lack of attention to contralateral side of object. See only half of object vs. Lack of attention to contralateral space compared to own midline. Don't see half of stuff in space. |
left hemisphere vs. right hemisphere | Knows & attends to right body & personal space vs. Knows & attends to right & left body & personal space |
hemispatial neglect ax | Assess the bottom of pyramid first Assess ADLs & functional tasks How pt starts & carries out visual scanning to complete a task that needs visual search |
types of hemispatial neglect ax | Apples test- allocentric & egocentric neglect LOTCA Cognistat BIT RPAB Reading ax |
hemispatial neglect intervention | Specific task practice Teach to reorganize scanning pattern Attention training Activities to reinforce systematic & organized visual search Dynavision |
prisms | Adaptation improves left neglect by encouraging compensation through contribution of left, undamaged hemisphere |
body schema disorders | Know position of parts of body & spatial relationships between them Integrate vision, proprioception, tactile, pressure sensation Due to damaged parietal lobe, somatosensory integration |
pusher syndrome | Incorrect perception of vertical midline Loss of sensation from affected side Left spatial neglect possibly Lean/ active pushing to hemiplegic side |
body scheme ax | Observational (drawing) & standardized (RPAB) ax |
body scheme tx | Remedial approach often used Reinforce body knowledge Tactile & proprioceptive stimulation Incorporate affected limbs into occupational performance |