Midterm 2: Perimetry

Question 1

Region of space where one eye can see but the other can not.

Answer 1

Monocular temporal crescents.

Where FOV does not overlap with both eyes

Question 2

What did Traquair say about visual field?

Answer 2

• compared it to an island, surrounded by sea of blindness.

- as you get further away from fovea, your sensitivity to seeing the target drops and can’t see it as well.

Question 3

About how many degrees from the central FOV would you find the blind spot?

Answer 3

about 15-18 degrees

Question 4

Where is the visual field most sensitive to detecting difference in target luminance and background luminance?

Answer 4

At the fovea

Question 5

What do you call an abnormal reduction in sensitivity of an area the visual field? Where do people always have a depression?

Answer 5

A depression. Optic nerve because no photoreceptors

Question 6

What is isopter?

Answer 6

During kinetic perimetry, the isopter is the measured values of their field of view measured by a constant stimulus size and constant luminance.

Question 7

If you increase the stimulus size or luminance, would this increase or decrease isopter?

Answer 7

Increase

Question 8

Kinetic perimetry stimulus

Answer 8

Constant luminance and constant stimulus size. Changing the location of the stimulus.

Question 9

Static perimetry stimulus characteristics

Answer 9

Stimulus is changing luminance, remaining same size at different locations. Wants to find the increment detection threshold for certain parts of the visual field.

Question 10

On a right eye, would the blind spot be left or right of the central vision?

Answer 10

Right

Question 11

Binocular visual field in degrees. Horizontal and vertical

Answer 11

Horizontal: 120 degrees
Vertical: 135 degrees

Question 12

Total visual field in degrees. Horizontal and vertical

Answer 12

Horizontal: 200 degrees
Vertical: 135 degrees

Question 13

What is an apostilb?

Answer 13

Unit of intensity for Goldmann kinetic perimetry stimuli.
units are candelas/ pi x meter squared
-are in log unit steps
-values 1-4 and 0.5 log steps

Question 14

Are large or smaller stimulus targets better for detecting the isopter edges?

Answer 14

Smaller targets are better

Question 15

Is a V4e stimulus large and bright or dim and small?

Answer 15

Largest and brightest possible

Question 16

What do the Roman numerals mean for the stimulus? What does the “1e, 2e, 3e” mean?

Answer 16

Roman numerals refer to size. Higher Roman numeral = larger stimulus
“1e, 2e…” refers to brightness. Larger number = more bright

Question 17

Describe x and y axis of the 2-D perimetry hill of vision graph on kinetic perimetry

Answer 17

Y-axis: sensitivity

X-axis: retinal postion

Question 18

Difference of hill of vision between scotopic and photopic

Answer 18

scotopic graph is much larger but should have a depression in the very center since we have cones in the fovea and they aren’t good in dark.

Question 19

What background luminance do most automated perimeters use?

Answer 19

10 cd/m^2 or 31.4 asb which is low photopic range

Question 20

What kind of contour does a large stimulus have on a graph?

Answer 20

Flat. Meaning it stimulates a lot of receptive fields

Question 21

What kind of contour does a smaller stimulus have?

Answer 21

Steeper. It tests fewer receptive fields so it is more sensitive.

Question 22

Two factors of stimulus duration of static perimetry

Answer 22

Temporal summation:

• Photopic- only need 10-50 msec
• Scotopic- 100 msec

Saccadic eye movement latency:
-Approx 250 msec. If it stays on at least 250 msec, patient may saccade toward the stimulus.

Question 23

best duration for stimulus In static perimetry?

Answer 23

longer that critical duration but shorter than saccadic eye movement latency.
-around 200 msec

Question 24

Does a high number (5) on log asb indicate good or bad sensitivity?

Answer 24

Good

Question 25

What does it mean if a patient has a sensitivity of 0 decibels?

Answer 25

They were not able to detect brightest stimulus given to them. Does not mean they are blind

Question 26

What do we define the scotoma by?

Answer 26

By its depth. Relative vs. Absolute scotoma

Question 27

What is relative scotoma

Answer 27

over threshold but measurable and doesn’t mean total loss of vision

Question 28

Absolute scotoma

Answer 28

no light perception

Question 29

Positive scotoma

Answer 29

patient is aware of loss in sensitivity

Question 30

negative scotoma

Answer 30

patient is unaware of loss of sensitivity

Question 31

What kind of scotoma is the optic nerve?

Answer 31

negative scotoma. We do not perceive vision is gone due to filling in.

Question 32

Perceptual visual neglect

Answer 32

failure to attend to sensory information on one side of the body

Question 33

Motor visual neglect

Answer 33

failure to execute movements to one side of the visual field.

Question 34

Why does a person usually exhibit visual neglect?

Answer 34

Usually a contralateral lesion in dorsal extra-striate visual pathway

Question 35

Visual extinction

Answer 35

usually occurs with parietal lobe damage

the visual neglect only emerges when stimuli are presented simultaneously

Question 36

If pt has right parietal lobe lesion, where will patient ignore stimulus?

Answer 36

patient will ignore left visual field when stimulus is present in both left and right visual fields.

Question 37

How to perform useful visual field

Answer 37

Having patient focus on object at fixation and present another stimulus in periphery.

Question 38

Useful visual field on elderly

Answer 38

sometimes restricted even though traditional visual field may be normal

Question 39

What is flicker defined form perimetry useful for?

Answer 39

Detecting visual field loss in early glaucoma patients