Foundations Of Visual Field Interpretation Flashcards
1
Q
Threshold determination
A
Age matches normal data are used to compare patients data -normal range determined by: —Sensitivity of each retinal point —upper 95% as normal —lower 5% as abnormal
2
Q
When is suprathreshold used for
A
Disability and driving
3
Q
The lower the decibels
A
The brighter the stimulus
4
Q
The part of the visual field that corresponds to the fovea
A
Fixation
5
Q
Localized defects/depressions surrounded by normal vision
A
Scotoma
6
Q
Defect that persists when the maximum stimulus is used, e.g. blind spot
A
Absolute scotoma
7
Q
Defect that is present to weaker stimulus but disappears with brighter stimulus
A
Relative scotoma
8
Q
Reduction both peripheral and centrally
A
Generalized depression
-cataract
9
Q
Peripheral depression
A
RP
10
Q
Which VF has the least amount of points tested
A
24-2
11
Q
What is 10-2 used for
A
Extreme glaucoma
Plauqeunil
12
Q
60 points 2 degrees apart
A
10-2
13
Q
54 points 6 degrees apart
A
24-2
14
Q
74 points
A
30-2
15
Q
What are the reliability parameters
A
Fixation loses
False positives
False negative
16
Q
If the VF is not normal…
A
- what was the fixation loss
- what was the false positive and false negative %
- were they properly refracted
- do they have a ptosis/heavy
17
Q
What is the most reliable relaibiltoy parameters
A
False positive
18
Q
Trigger happy patients, responses to stimuli when no target is present
A
False positive
19
Q
What si considered unreliable FP
A
> 33%
-if the FP exceeds 15% the field is considered unreliable and should be re run
20
Q
Failed to response to suprathreshold stimuli, indicates fatigue, inattentivenss
A
FN
21
Q
Clover leaf pattern
A
FN
22
Q
What is considered unreliable with FN
A
> 33%
23
Q
Fixation loses
A
Monitored by blind spot and gaze tracking
24
Q
If the FL rate exceeds ____ it is flagged
A
20%
25
Threshold sensitivities measured at each test point, indicated in decibels
Numeric grid
26
___ dB indicates the max brightness target available for that test
0
27
Raw data
Numeric grid
28
Where should numbers be the greates in the numeric gird
In the center, less in the periphery
29
If there is <0 on numeric grid
Does not mean totally blind int hat spot but that the patient could not see the largest and brightest target available for that test
30
Provides an approximate picture of the field, good for patient education
Gray scale
31
Appears as numbers and graphics in the central left area of the printout, represents the difference between the measures threshold of each individual tests location and the age corrected normal vale for that location
Total deviation plot (dB); upper plot
32
Negative values for the total deviation plot; upper plot
Indicate sensitivities which are below the median age-corrected sensitivity
33
Positive values in the goal devation plot; upper plot
Indicate sensitivities which are above the median age corrected sensitivity
34
Graphics display plots the signicance of deviations found in the upper plot, using a small dot for a point within the range of 95% of the normal values or with a shaded box. See p value
Total deviation plot (dB); lower plot
35
Indicates ALL test locations that are outside a normal range
Total deviation plot
36
Most common reasons for overall reduction or generalized depression
Cataracts
Incorrect trial lenses
Poor test taker
37
Takes the total deviation plot and adjusts it upwards to downwards to screen out generalized depression, highlights only significant localized VF loss
Pattern deviation plot
38
Symbols for pattern deviation plot
Uses the same symbols as the total deviation plot to show points which are significantly worse than normal P value
39
Single most uself analysis on an SFA printout
Pattern deviation plot
40
Highlights subtle, but significant localized variations that might otherwise be masked, early defects show up sooner on probability map than on gray scale plot
Pattern deviation plot
41
It total deviation plot and pattern deviation are about the same
There is little to no generalized loss
42
If abnormal TD plot and normal PD plot
Cataract, incorrect Rx
43
If normal TD plot and abnormal PD plot
Trigger happy
44
Significance of deviations from Normal in the probability plots (P value)
Indicated in the total deviation probability plot (P value)
45
A 2% symbol indicates that fewer than 2% of normal patients have a sensitivity
That low or lower
46
Found on the lower right hand corner of the printout, single number representations of the VF, MD, PSD
Global indices
47
Shows how much (on average) the whole field departs from normal
Mean deviation
48
(+) MD
Better than average
49
(-) MD
Less than average
50
Abnormal MD
P<0.5%
| -less than 0.5% of the population has a mean deviation larger than the value found on the test
51
Height of the hil of vision compared to age matched normals.
MD
52
Measures the extent to which the threshold determinants at different locations differ from each other
Pattern standard deviation (PSD)
53
This does not change with media (cataract)
Pattern standard deviation (PSD)
54
The higher the PSD, the more
Irregular the pattern
| -high PSD=more localized defects=more indicative of pathology
55
Indicates the SHAPE of the hill of the vision
Pattern standard deviation
56
If MD is abnormal and the PD is normal
Generalized defect
57
Normal MD and abnormal PD
Small localized defect
58
MD and PD both abnormal
Large defect with a localized components
59
Interpretation and report
- look at both eyes together
- does the field make sense compared to other clinical findings
- make sure data trustworthy
- evaluate defect; any type of defect
- repeatability of the defect
- probable diagnosis
60
Documentation of HVF
- make statements referencing reliability
- make statement regarding pattern, depth, and size of VF loss
- make statements which correlates other exam findings with the VF
- always remember to wrtie signature next to signatures
61
Reasons for VF defect
- glaucoma
- retinal abnormalities
- developmental optic disc anomalies
- optic neuropathies
- chiasmal lesions
- homonymous hemianopia
- functional vision loss
62
Glaucomatous progression rate
Almost 10x faster than the normal rate of decline of visual function with age
-structural change usually precedes loss but not always
63
Neuro causes of field loss
Stroke
Optic neuritis/neuropathy
Chiasmal tumors
Raised intracranial pressure
64
Visual field defects obey
Anatomy
65
Interpretation of the VF loss reveals the
Location
66
Finding the location of the VF loss reveals the
Lesion
67
Clues from exam
VA
Confrontational VF
RAPD
Color vision
68
How does a droopy lid appear on a VF?
Looks like an accurate defect
69
Ring defect on VF
Lens artifact
70
Small pupil in VF
Lack of peripheral
71
Ptosis
Superior field defects
72
Called the true positive rate. Defined as the proportion of people with the disease who will have a positive result
Sensitivity
73
A highly sensitive test is one that does what
Correctly identifies patients with a disease
74
A test with 100% sensitivity will identify
All patients who have the disease
75
If a person has a disease, how often will the test be positive (true positive rate)?
Sensitivity
76
If the test is highly sensitive and the test result is negative you can be certain
That he don’t have disease
77
A ______ helps rule out disease when the result is negative
Sensitivity
78
TP/(TP+FN)
Sensitivity
79
The specificity of a test (also called the TN rate) is the proportion of people without the disease who will have a negative result
Specificity
80
Refers to how well a test identifies patients who do not have a disease
Specificity of a test
81
A test that has 100% specificity will identify
100% of patients who do not have the daises
82
If a person does not have the diasease, how often will the test be negative (TN. Rate)
Specificity
83
If the test result for a highly specific test is positive you can be certain that
They actually have the disease
84
TN/(TN + FP)
Specificity
85
High sensitivity tests have low
Specificity
-they are good at catching actually cases of the disease but they also come with a fairly high rate of false positive (mammograms)
86
Low sensitivity/high specificity
UTI
