Indices of Visual Field Loss (M1)

Question 1

What does a visual field loss in both eyes suggest?

Answer 1

possible post-chiasm lesion

Question 2

For the Humphrey analysis, what is the numeric value of deviations for age-related data adjusted for any change in overall sensitivity? 1. What do the symbols represent? 2

Answer 2

1. pattern deviation plot

2. probability that a data point is normal

Question 3

What do the upward lines of the gaze tracking indicate?

Answer 3

degree of gaze error during stimulus presentation

Question 4

For the Humphrey analysis, what represents the difference, in dB, between the patients test results and those of age-related normals? 1. What do the symbols represent? 2

Answer 4

1. total deviation plot

2. probability that a data point is normal

Question 5

When the pattern deviation plot is more disturbed than the total deviation plot, what does it indicate?

Answer 5

trigger-happy patient (high false positives)

Question 6

What is the term for responses by the patient when no stimulus is being presented? 1. What is a way to avoid these? 2. What is the ideal value for this? 3

Answer 6

1. false positive errors
2. tell pt to expect some long pauses between seen stimuli
3. less than 33% (some say 15)

Question 7

For the event analysis of the guided progression analysis, what is the term used when 3 or more points are significantly reduced compared to baseline on two consecutive exams? 1. Three consecutive exams? 2

Answer 7

1. possible progression

2. likely progression

Question 8

What is the summary index which determines the difference between the subjects threshold values and “normal” values for a person of the same age, averaged over all points in the VF? 1. What value from this is considered legal blindness? 2. Can this be used to show progression? 3

Answer 8

1. mean deviation
2. -22dB
3. yes but doesn’t account for cataract

Question 9

What is the differences and similarities between the mean deviation and visual field index?

Answer 9

1. diff: uses pattern deviation plot
2. same: weighted for center
3. less affected by cataract
4. 100% is best score instead of 0
5. same: can be used as indicator of progression

Question 10

What is the term for if the patient responds to a stimulus presented within the blind spot? 1. What is the ideal value for this? 2

Answer 10

1. fixation losses

2. less than 20%

Question 11

What is the Humphrey software for measuring change over time in visual fields? 1. What is the analysis it uses to show significant change that is worse than baseline? 2. Analysis used to quantify rate of change over time? 3

Answer 11

1. guided progression analysis (GPA)
2. event analysis
3. trend analysis

Question 12

What measures the variability of threshold values across the VF relative to that of a “normal” person of the same age and reflect the extent of localized defects? 1. What are normal values for normal patients? 2. Blind patients? 3. Can this be used to show progression? 4

Answer 12

1. pattern standard deviation
2. near zero
3. near zero (highest in moderate levels of blindness)
4. no

Question 13

What is the term for when a stimulus brighter than threshold is presented and patient does not respond? 1. When is this often seen? 2. What is the ideal value for this? 3

Answer 13

1. false negative errors
2. inattentive patients and higher in glaucoma/field loss patients
3. less than 33%

Question 14

What do the downward lines of the gaze tracking indicate?

Answer 14

unsuccessful gaze tracking at that time (blink)

Question 15

What test evaluates five zones in the superior field and compares with corresponding areas in the inferior field?

Answer 15

Glaucoma hemifield test

Question 16

What are the general steps to take when interpreting visual fields?

Answer 16

1. reliable?
2. With both fields in front of you, normal?
3. VF loss in both eyes or one?
4. location of VF loss
5. shape of VF loss
6. progression of VF loss
7. need for more testing or consult?