Automated Perimetry

Question 1

True or False:

The test flash in automated perimetry is a fixed size.

Answer 1

True

Question 2

What is the most commonly used TF size?

Answer 2

Goldmann III

Question 3

What about the test flash in VF testing is changed?

Answer 3

The intensity changes in order to determine threshold

Question 4

When is it appropriate to use a larger stimulus size?

Answer 4

For individuals with poor visual acuity.

Question 5

In what unit are threshold values expressed in?

Answer 5

Decibels (dB)

Question 6

What does the threshold value obtained tell us?

Answer 6

How much the TF must be decreased from the max luminance to reach threshold.

Question 7

If 10dB was obtained for threshold, what does this tell us?

Answer 7

10 dB = 1.0 log unit LESS THAN max luminance.

1.0 log unit = 10x less than 10,000 asb = 1,000 asb

Question 8

What does a higher dB number tell us?

Answer 8

The higher the dB, the more sensitive the eye is for a given location.
- Less luminance is needed for the patient to detect light

Question 9

Convert 20dB to asb

Answer 9

20 dB = 2.0 log units = 20x less than 10,000 = 500 asb

Question 10

What is a fixation loss?

Answer 10

Light is presented in the patient’s blind spot.

• If the patient is fixating where they’re supposed to, they should not be able to see these lights.
• If the patient clicks that they see these lights, that is a fixation loss because they’re not paying attention to where they need to be.

Question 11

What is considered acceptable for fixation losses?

Answer 11

It is recommended that the fixation losses not exceed 20%

Question 12

What does a reading of fixation loss greater than or equal to 20% tell us?

Answer 12

The results may not be reliable or the patient may have fixation problems

Question 13

In ‘graze tracker,’ what do the upward lines reflect?

Answer 13

The deviation from the baseline.

For example, the patient is moving eyes a lot - deviating from the baseline (central light).

Question 14

In ‘gaze tracker,’ what do the downward lines indicate?

Answer 14

An inability to make a measurement (e.g., a blink).

Question 15

What is a false positive?

Answer 15

Signifies that the patient pushes the button before the stimulus is presented; they are “trigger happy.”

Question 16

At does a reading of greater than 15% false positives tell us?

Answer 16

That the data is unreliable

Question 17

True or False:

False positives are one of the most important and useful reliability indices.

Answer 17

True!

It’s a way to show the subject’s engagement; it’s not a fixation problem, rather, they’re not waiting to see the target.

Question 18

What are false negatives?

Answer 18

When the patient misses a stimulus that is brighter than one that was seen previously.

For example, the subject clicks the button for a the first few trials stating they detect a light level. When a higher illuminance is presented, the patient does not click. They should see it because they responded for lower luminance.

Question 19

For a sensitivity plot/numeric plot, what unit are the values in?

Answer 19

Threshold values in decibels (dB)

Question 20

In a sensitivity/numeric plot, what does a dB reading signify?

Answer 20

How much the TF must be decreased from the max luminance to reach threshold.

Question 21

What is a normal threshold for a young observer in a sensitivity/numeric plot?

Answer 21

38-40 dB.

Question 22

Which plot is the basis for 5 other plots included in the VF printout?

Answer 22

The sensitivity/numeric plot.

Question 23

What is the relationship between threshold and sensitivity?

Answer 23

The lower the threshold (i.e., the less luminance needed for the patient to detect the light), the greater the sensitivity.

Question 24

What does the total deviation plot convey?

Answer 24

The difference in decibels between the patient’s results and the averaged age-corrected normal values at each point in the visual field.

Question 25

What do negative numbers in a total deviation plot signify?

Answer 25

Lower sensitivity than the averaged age-corrected normal value.

Question 26

What do positive numbers in a total deviation plot signify?

Answer 26

Higher sensitivity than the averaged age-corrected normal value.

Question 27

What does the total deviation probability plot convey?

Answer 27

Expected % of normal subjects to have a loss of exactly the same magnitude.

Question 28

What does the pattern deviation plot convey?

Answer 28

The same as the total deviation plot, except that the numbers are corrected for any overall sensitivity loss that might be caused by cataracts, small pupils, or cloudy media.

Question 29

What does the pattern deviation probability plot convey?

Answer 29

The same as the total deviation probability plot but corrected for any overall sensitivity loss due to cataracts, small pupils, or cloudy media.

Question 30

Which plot is considered to be the single most useful?

Answer 30

The pattern deviation probability plot.