Week 6: Assessment of Visual Deficits Flashcards
(93 cards)
1
Q
What sense takes us further into the environment?
A
Vision
2
Q
Visual system is our most important sense in regard to…
A
- learning, memory, recall
- commuication
- spatiotemporal orientation
- early warning system of pleasure or danger
- visual manual and visual motor activities
3
Q
What are foundations of basic visual function?
A
oculomotor control
visual fields
visual acuity
4
Q
What is highest order visual perceptual process?
A
visual cognition
5
Q
Ability to manipulate and integrate visual input with other sensory info to gain knowledge, solve problems
A
visual cognition
6
Q
T/F: Visual cognition can occur without visual memory
A
False. Cannot occur without visual memory
7
Q
What is hierarchy of visual perception?
A
Visuocognition Visual memory pattern recognition scanning attention oculomotor/visual fields/visual acuity
8
Q
Ability to see small visual detail “keenness of sharpness”
A
visual acuity
9
Q
what does good acuity enable?
A
speed and accuracy of info processing and facilitates decision making
10
Q
How is visual acuity commonly measured?
A
having client read progressively smaller optotypes on chart (letters, numbers, symbols). Uses Snellen fraction 20/20
11
Q
Snellen Fraction
A
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.
12
Q
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
A
visual acuity
13
Q
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.
A
Contrast sensitivity function
14
Q
T/F: Both high and low contrast acuity must be measured to obtain accurate assessment of acuity function.
A
True
15
Q
ability to see objects at a distance
A
distance acuity
16
Q
ability to seek objects clearly as they come close to eye
A
reading/near acuity
17
Q
How to measure reading acuity?
A
having client read sentences in progressively smaller sizes of print
18
Q
______ enables eye to maintain clear focus on objects as they come closer
A
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
19
Q
_____ cranial nerve controls accommodative process
A
Third, oculomotor.
20
Q
Person with lesion to oculomotor nerve….
A
demonstrate normal distance acuity but impaired reading acuity
21
Q
Accommodation can be affected by…
A
presbyopia (by product of aging) and lesion to cranial nerve 3 oculomotor
22
Q
What are 3 most common optical defects that reduce acuity?
A
Myopia (nearsightedness)
hyperopia (farsightedness)
astigmatism
23
Q
image of object is focused at a point in front of retina and is blurred when it reaches retina
A
myopia
24
Q
image comes into focus behind retina, causes image to remain out of focus on retina
A
hyperopia
25
light is focused differently by 2 meridians 90 degrees apart
astigmatism
26
visual acuity deficits primarily occur as result of impairment in three areas:
1. disruption of ability to focus light onto retina
2. inability of retina to accurately process image
3. inability of optic nerve to transmit info to rest of the CNS for processing
27
Persons older than 80 years has visual impairment that affects the...
retina! (can be caused by stroke or brain injury)
28
Most common cause of optic nerve damage in brain injury is....
trauma
29
Most common fractures in young adults and kids?
indirect trauma... facial or blunt forehead fractures resulting in unilateral injuries
30
What conditions can cause optic nerve damage?
trauma, glaucoma, MS
31
loss of central acuity result in...
inability to discriminate small visual details and distinguish contrast and color
32
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
33
Mobility will be affected and can't identify landmarks, detect motion, maintain orientation when there is loss of...
peripheral acuity
34
This loss in _____ acuity can reduce independence in driving, shopping, participation in community activities.
peripheral acuity
35
All assessment of performance skills begins with...
observation of client's performance in daily activities
36
If client is complaining of inability to read print or that print is too small/faint to read...
deficit in visual acuity
37
If client complains print is disrupted, parts of words missing, words run together ...
deficit in visual acuity
38
If client complain unable to distinguish between colors of similar hue, or detect low contrast substances such as water spilled on floor...
CSF deficit
39
If decrease in visual acuity, what needs to be measured?
high and low contrast acuity
40
How is high contrast acuity measured?
1. for distance using test chart at distance of 1m or greater
2. for reading, use text card at 16 inches (40 cm)
41
When measuring visual acuity, what two things are needed?
Illumination and held at specified distance from client
42
Client's acuity level is determined by...
smaller line of optotypes that can be read with good accuracy (don't look at how long it takes them)
43
What is lowest measure OT works with?
20/1000 (instead of 20/200)
44
When client's acuity is below 20/200 they are...
referred to low vision specialist for evaluation
45
LeaNumbers Low Vision test chart and Warren Text Card
example test charts measure visual acuity in low vision ranges
46
How to assess CSF?
Similar to visual acuity, but instead of symbols/words getting smaller, their contrast changes, getting fainter.
47
Most portable and least expensive CSF test?
Lea Numbers low contrast screener - part of BiVABA
48
T/F: when assessing visual acuity, OT is responsible for diagnosing cause of deficiency
False. They are supposed to link presence of deficiency to limitation of occupational performance
49
When OT determines client as reduced visual acuity, how is this info used?
Modify activities and environment so client can compensate for loss and successfully complete daily activities (ex. can't read prescription, so OT will enlarge print)
50
Is external world that can be seen when we look straight ahead
visual field
51
What results in VFD (visual field deficit?)
damage to receptor cells in retina or optic pathway that relays retinal info to CNS
52
loss of vision in half of visual field in eye
Hemianopia
Hemi = half
Anopia = blindness
Homonoymous means deficit is same in both eyes
53
What strategy does person with VFD use to compensate for blind portion of visual field?
they narrow the scope of scanning, turning head very little and limit visual search to areas immediately adjacent to seeing side of body (does not adopt wider search strategy)
54
This process whereby CNS samples a visual array and internally completes visual scene based on expectation of visual info that would be found in array... outcome is viewer perceives that he is seeing a complete visual scene
Perceptual completion. Provides speed in info processing by enabling person to construct complete visual scene based on particle visual input (able to adapt to moving environment)
55
T/F: in those with visual field loss, presence of perceptual completion makes it difficult for client to determine how his visual field as changed.
True. Because of PC, client with VFD not aware of absence of vision.. CNS can't place objects that it does not actually see... so client might run into chair on blond side or not find items placed on blind side. Not being aware of VFD means harder to drive, traverse busy environment
56
Even those who are aware of VFD, still slow and delayed...
can't determine actual border of seeing field (due to perceptual completion), slows down to search affected side
57
Give example of difficulty reading with hemianopia
Client with left hemianopia may read "She should not shake the juice as "He should make juice" (they lose confidence in paying bills, managing checkbook -if the misread 28 for 23 dollars, example)
58
If VFD same side of dominant hand, difficulty with fine motor skills...
like handwriting
59
What changes occur with VFD?
narrow scope of scanning, slow scanning toward blind side, missing or misidentified visual detail, reduced visual monitoring
60
What occupations affected with VFD?
mobility, reading, writing, personal hygiene, grooming, medication management, financial, meal prep, color selection, home management, phone use, yard work (larger field, more difficult so basic ADLs not as bad as IADL)
61
Side effects of VFD?
anxiety (going to new place, or crowded place) "crowditis."Can lead to social isolation, nauseated, depression)
62
Perimetry
process of measuring visual field.
range from simple bedside assessments (confrontation test) which give gross indication of field loss, to very slow precise imaging of scanning laser opthalmoscope)
- test selected depends on availability and cost of test and ability of client to participate in testing
63
Must be specially trained technician in enter that purchased $12,000 instrument
SLO (scanning laser opthalmoscope)
64
does not incur any expense and be performed anywhere
Confrontation testing
65
Samples of perimetry assessments...
Damato campimeter, manual bowl perimeters (goldmann) and automated bowl perimeters (Humphrey)... more expensive = more precise. Automated, computerized is best
66
What are three parameters of perimetry testing?
1. fixation on central target by client while testing is performed
2. presentation of target of specific size and luminosity in designated area of visual field
3. Acknowledgement of second target without breaking fixation on central target
67
t/f: perimetry testing done with either static or kinetic presentation of target
true.
static - target appears in specified area of visual field without being shown moving to that location
kinetic - target moves in from periphery until it is identified
68
Client places his or her chin on chin rest and fixates on central target inside bowl shaped device... as person fixates on central target, lights are displaced inside bowl in varying locations and intensities. Client responds to each seen light by pushing small button
This happens during automated perimetry. Result is measurement of areas of absolute loss (no response) and relative loss (decreased retinal sensitivity) within field.
69
This screen consists of black felt screen with grid stitched onto felt where it is only seen by examiner. Client instructed to fixate on center of screen as examiner moves or places a white target attached to black wand in certain areas. client indicates where argot is seen without breaking fixation of center. If client does not see target when presented, point in visual field is a loss.
Tangent screen
70
How can OT assess for VFD?
simple perimetry testing (confrontation testing) + observation of client performance.
71
Beside exam that provides a crude indication of visual field loss
Confrontation testing.
static test - examiner sits in front of client at meter distance and has client fixate on centrally placed target (examiner's eye). Examiner holds up 2 targets in each of 4 quadrates of visual field. Client indicates whether targets can be seen.
Kinetic test - examiner stands behind client and moves target (penlight) from periphery while client fixates on central target. Client indicates as soon as target is noticed.
72
examiner sits in front of client at meter distance and has client fixate on centrally placed target (examiner's eye). Examiner holds up 2 targets in each of 4 quadrates of visual field. Client indicates whether targets can be seen.
Static confrontation testing
73
examiner stands behind client and moves target (penlight) from periphery while client fixates on central target. Client indicates as soon as target is noticed.
Kinetic confrontation testing
74
What should OT do if confrontation test shows no deficit but clinical observations suggest there is one?
Clinical observations should carry greater weight.
75
Portable test card provide precise measurements of central 30 degrees of visual field... has 30 targets... client instructed to fixate on one of the numbered targets and test stimulus is then sown in central window and client indicates whether circle is seen. If client can't see black circle, point in visual field is a loss. Done when all mapped out
Damato 30 point multifixation campimeter
76
What are reasons clients might not do well on perimetry testing?
Has limited attention, language, cognition. also hard to distinguish between VFD or visual attention deficit.
77
What are some examples that indicate when VFD present during observation?
- Client changes head position when asked to view objects placed in certain plane
- Client consistently bumps into objects on one side
- Client misplaces objects in one field
- Client makes consistent errors in reading
78
T/F: Perimetry tests whether VFD present and size and location of deficit. Also determines intervention.
False. Perimetry tests whether VFD present and size and location of deficit. For intervention, OT needs to determine whether client is able to compensate for VFD in performing daily activities (need to identify limitations).
79
this test provides effective way to measure interferences of VFD in reading performance
VSRT visual skills for reading test
80
Client asked to read single letters and words printed on card. 3 diff. versions of test card in 4 font sizes are included to accommodate clients with low vision and permit to retesting. Words not in context and designed so they can be misread and still make sense. Test measures reading accuracy and corrected reading rates and provides info on types of reading errors made by client
VSRT visual skills for reading test
81
Test provides info about client's accuracy in reading numbers, client required to copy down telephone numbers that include numbers easily misread by persons with VFD like 6,8, 9, 3
Telephone Number Copy
82
How do you effectively compensate for VFD?
Execute organized and thorough search of blind file by using seeing portion of visual field. So client with left VFD must use right visual field to search both left and right fields.
Hard to search peripersonal space (space around body) and extra personal space (space extending body).
83
What performances affected by deficiencies in peripersonal space?
basic adls - grooming, dressing, reading, writing, and IADLs like meal prep or leisure activities
84
What performances affected by deficiencies in extrapersonal space?
mobility and activities in community, outside (shopping, driving)
85
Hemi-inattention is often confused with the presence of a left VFD in the client
When a client has VFD, they will attempt to use visual attention to search and compensate in the blind side, but with hemi-inattention there is no drive to search so no compensation occurs. If the conditions occur together, visual neglect occurs. This can lead to no vision directed to the left side and often reduced use of limbs and auditory ability on the left side. Leads to poor rehabilitation outcomes
86
These functions should be assessed before visual attention
Visual attention can be affected by deficits in visual acuity, oculomotor function and visual field.
- Aphasia and motor impairment can also affect performance on assessments for visual attention
87
Emphasis in assessment is on observing how a client initiates and carries out visual scanning to complete a task requiring visual search
During assessment OT should see if client initiates organized search strategy, and if client can carry out the search strategy in an organized manner, if client obtains complete visual information from a visual search, identify visual detail correctly, and can client search for info even when complexity of task increases
88
Good visual attention characteristics
organized, symmetric, thorough, resilient, and consistent. Results in good accuracy and speed
89
OT must differentiate between VFD and hemi-inattention and is able to do this by observing compensatory strategies
The OT must look at cause of errors when identifying objects
• Determine severity of inattention when both deficits occur to determine the ability to compensate with search strategies
oThe visual search tests are often with pencil and paper
90
is to achieve and maintain focus on an object
Purpose of oculomotor function is to achieve and maintain focus on an object. Foveation = foveas focused on object and is achieved by head movement, gaze shift, and eye movements that keep target stabilized on the retina. also provides binocular vision, which ensures perception of a single object even though the CNS is receiving two different images. Double image (diplopia) can occur if there is a significant difference in acuity or alignment between the eyes
91
Presence of diplopia creates perceptual distortion, which can affect...
hand-eye coordination, postural control, and binocular use of eyes. Occupational impact depends on where diplopia occurs in the focal range: within 20 inches of the face will impact activities requiring hand-eye coordination, i.e. writing or pouring liquids. Diplopia occurring at a distance greater than 4 feet will affect walking, driving, playing sports, etc.To eliminate double image, client will often assume a head position that avoids field of action of paretic muscle. Important to be aware of because this can look like a neck muscle issue, when really client is making adjustment for vision. They may complain of fatigue after reading and may complain that print swirls and moves after viewing it for a while. Important to be aware of when evaluating so that this is not falsely attributed to lack of attention
f. Many factors can affect vision, and thus expertise is needed to determine if an oculomotor deficit is causing the impact on occupation. OT practitioners should work with an optometrist or opthamologist.
92
Purpose of assessment of oculumotor...
Purpose of assessment is to determine whether limitations in occupational performance are due to a dysfunction in the oculomotor system, not to determine if it is due to a brainstem injury or cranial nerve lesion.
93
Assessing client involves listen and look approach where practitioner listens to complaints while observing client. What are steps?
First step is to obtain a visual history from the client to determine preexisting conditions/if the client requires corrective lenses. Second step is to ask about diplopia and where/when it occurs, which can suggest which cranial nerve has been injured.
Should make note of patterns of visual difficulty. Third step is to observe eyes and eye movements for abnormalities. OT observes symmetry of eye movement, whether the eyes move the same distance in each direction, whether the eyes are able to stay on target, and whether client is able to hold eyes in deviated position for 2-3 seconds at the end of the range.
Observing eyes as they track an object moving toward the bridge of the nose tests convergence, most adults can track and focus on an object to a distance of approx 3 inches from bridge of nose
f. Final component of testing is diplopia testing which only occurs if client complains of diplopia, should take note if there is tropia (noticeable deviation of one eye while other is focusing) or phoria (no noticeable deviation)
g If tropia, do cover/uncover test. If phoria, do a cross or alternate cover test.
h. Clients with tropias generally complain of constant diplopia when viewing objects and clients
with phorias complain of diplopia only intermittently
i. Info gained from assessment should be compared with clients’ visual complaints and referrals made as needed
