Week 6: Assessment of Visual Deficits Flashcards
What sense takes us further into the environment?
Vision
Visual system is our most important sense in regard to…
- learning, memory, recall
- commuication
- spatiotemporal orientation
- early warning system of pleasure or danger
- visual manual and visual motor activities
What are foundations of basic visual function?
oculomotor control
visual fields
visual acuity
What is highest order visual perceptual process?
visual cognition
Ability to manipulate and integrate visual input with other sensory info to gain knowledge, solve problems
visual cognition
T/F: Visual cognition can occur without visual memory
False. Cannot occur without visual memory
What is hierarchy of visual perception?
Visuocognition Visual memory pattern recognition scanning attention oculomotor/visual fields/visual acuity
Ability to see small visual detail “keenness of sharpness”
visual acuity
what does good acuity enable?
speed and accuracy of info processing and facilitates decision making
How is visual acuity commonly measured?
having client read progressively smaller optotypes on chart (letters, numbers, symbols). Uses Snellen fraction 20/20
Snellen Fraction
20/20 means when standing at a distance of 20 feet, viewer can see letter that a person with normal vision can see at 20 feet. 20/200 indicate person standing at distance of 20 feet can see a letter that a person with normal vision could identify at 200 feet.
Ability to see high contrast, black on white optotypes. However, it is ability to detect high contrast features on one end of the continuum to ability to deter low contrast features on other end
visual acuity
Low contrast acuity… ability to detect borders of objects as they decrease in contrast from their backgrounds.. makes it possole to identify faint features of objects like protrusion of nose on face… need to negotiate environment safely.
Contrast sensitivity function
T/F: Both high and low contrast acuity must be measured to obtain accurate assessment of acuity function.
True
ability to see objects at a distance
distance acuity
ability to seek objects clearly as they come close to eye
reading/near acuity
How to measure reading acuity?
having client read sentences in progressively smaller sizes of print
______ enables eye to maintain clear focus on objects as they come closer
Accommodation.
As object comes closer, eye converge to ensure that the light rays entering eye stay parallel and in focus. The crystalline lens of eye thickens to refract light rays more strongly and shorten focal distance. Pupile constricts to reduce scattering of light rays
_____ cranial nerve controls accommodative process
Third, oculomotor.
Person with lesion to oculomotor nerve….
demonstrate normal distance acuity but impaired reading acuity
Accommodation can be affected by…
presbyopia (by product of aging) and lesion to cranial nerve 3 oculomotor
What are 3 most common optical defects that reduce acuity?
Myopia (nearsightedness)
hyperopia (farsightedness)
astigmatism
image of object is focused at a point in front of retina and is blurred when it reaches retina
myopia
image comes into focus behind retina, causes image to remain out of focus on retina
hyperopia
light is focused differently by 2 meridians 90 degrees apart
astigmatism
visual acuity deficits primarily occur as result of impairment in three areas:
- disruption of ability to focus light onto retina
- inability of retina to accurately process image
- inability of optic nerve to transmit info to rest of the CNS for processing
Persons older than 80 years has visual impairment that affects the…
retina! (can be caused by stroke or brain injury)
Most common cause of optic nerve damage in brain injury is….
trauma
Most common fractures in young adults and kids?
indirect trauma… facial or blunt forehead fractures resulting in unilateral injuries
What conditions can cause optic nerve damage?
trauma, glaucoma, MS
loss of central acuity result in…
inability to discriminate small visual details and distinguish contrast and color
Activities like reading, writing, fine motor coordination (reading recipes, paying bill, applying makeup, etc) will be affected when there is loss of…
loss of central acuity
Mobility will be affected and can’t identify landmarks, detect motion, maintain orientation when there is loss of…
peripheral acuity
This loss in _____ acuity can reduce independence in driving, shopping, participation in community activities.
peripheral acuity
All assessment of performance skills begins with…
observation of client’s performance in daily activities
If client is complaining of inability to read print or that print is too small/faint to read…
deficit in visual acuity
If client complains print is disrupted, parts of words missing, words run together …
deficit in visual acuity