Low Vision Flashcards
low vision
vision that can’t be fixed with lenses or surgery
mild low vision impairment
20/30 - 20/60
moderate low vision impairment
20/70 - 20/160
severe vision impairments
20/200 or worse
Profound vision impairment
20/500 - 20/1000
near total vision impairment
<20/1000
Total vision impairment
No light perception
Legally blind
20/200 or worse with corrective lenses
best corrected vision
best vision attainable with lenses
visual cognition
make decisions and gain knowledge based on vision
visual memory
recall memories of images
pattern recognition
identify features and distinguish from surroundings
visual scanning
saccadic eye movements to look at different objects
visual attention/alertness
attending to information and ignoring irrelevant sensory information
occulomotor controls
accommodation, convergence and diplopia
accomodation
focus on varying distances
convergence
focus on nearby objects with eye adduction
diplopia
double vision caused by weak muscles of 1 eye
Describe what Snellen Fraction means
at ___ distance, the viewer can see what a person with normal vision sees at ___ distance
presbyopia
difficulty seeing near objects
myopia
close objects seen clearer
- nearsightedness
hyperopia
distant objects seen clearer
- far sightedness
contrast sensitivity
ability to detect borders of objects
visual field
what someone sees when they look ahead
peripheral visual field
background info about one’s position in environment
peripheral vision parts of eye
rod photoreceptors
central visual field
central 20 degrees of vision
central vision field eye parts
macula and fovea
natural changes in vision over time
- decreased subcutaneous fat around eye
- decreased muscle strength
- cornea thickens and transparency decreases
- smaller pupils
- lens is thicker, less flexible, more opaque
age-related functional changes
- decreased ability to seeing close objects and eye coordination
- images are blurrier
- slower adaptations to light changes
-narrow visual field
Assessments for low vision
- Melbourne low-vision ADL index
- COPM
-Model of Human Occupation Screening Tool
Melbourne low-vision ADL index
assess impact of vision in I/ADLs
Model of Human occupation screening tool
informal observation of volition, habituation, skills and environment on occupational performance
environmental assessment
- lighting and glare
- contrast of items- stairs, showers, curbs
visual acuity assessment
assess near and distant visual acuity while wearing prescribed eyewear
contrast sensitivity assessment
Pelli-Robson contrast sensitivity chart
Peripheral visual field assessment
confrontation testing
central visual field assessment
Amsler grid
occular motor assessment
- assess for diplopia
- brain injury visual assessment
intervention for visual acuity
- eccentric viewing
- magnification
- lighting
- contrast
- organization
eccentric viewing
rotate head/trunk to compensate for central vision loss
sensory substitution
using other senses to make up for visual losses
- tactile bumps
intervention for visual field
- rotate head and trunk
- organized scanning
oculomotor function
- occlusion
-prism
-eye exercises - surgery
age-related macular degeneration
- blind spots in central vision affecting near-distant vision and activities
- objects appear distorted, straight lines appear wavy
- difficulty reading and low-contrast activities
glaucoma
- increased pressure reduces blood flow and loss in peripheral vision and blindness
- difficulties with functional mobility, night vision and reading
diabetic retinopathy
- high sugar in blood vessels leads to bleeding in vitreous
- fluctuating vision, decreased contrast sensitivity and night vision
cataracts
- lens becomes opaque or clouded
- blurry vision, glare, poor night vision
homonymous hemianopia
- following a TBI with half of visual field in each eye is lost
- difficulty reading and mobility
oculomotor dysfunction
- difficulty maintaining focus leading to diplopia
- difficulty with hand-eye coordination, reading, adjusting to light changes
visual neglect
- visual field deficit
- all daily tasks affected
- reading, driving, mobility
