Perimetry

Question 1

Meaning and purpose of perimeter

Answer 1

• the study of the visual field

- the VF is the area in which objects can be seen in the peripheral vision while the eye is focused on a central point

Question 2

Do we test VF monocularly or binocularly

Answer 2

Monocularly

Question 3

Purpose of perimetry

Answer 3

Provides a more standardized assessment of the visual field

-assessment of visual function throughout the visual field for detection and analysis of damage along the visual pathway

Question 4

Superior boundaries of the monocular field

Answer 4

60 degrees from the point of fixation

Question 5

Nasal boundary of monocular field

Answer 5

60 degrees from the point of fixation

Question 6

The inferior boundary of the monocular field

Answer 6

75 degrees from fixation point

Question 7

Temporal boundary of the monocular field

Answer 7

100 degrees from the point of fixation

Question 8

Monocular fields of vision in both eyes

Answer 8

Overlap

Question 9

Temporal crescent

Answer 9

Most temporal portion of vision from approximately 70-100 degrees which is seen only by one

Question 10

Why do glaucoma patients not realized they are losing vision

Answer 10

Because the VF in each are overlap, so the better eye can make up for the worse eyes loss

Question 11

Blind spot

Answer 11

• corresponds to the ONH

- located 10-15 degrees temporally

Question 12

The eye has a small and stable preferred retinal locus of fixation

Answer 12

Most people it is the macula, but low vision patients can have it elsewhere

Question 13

The center of ifixation correpsonds to

Answer 13

The anatomical center of the fovea where cone density is highest

Question 14

Dipalsment of the fovea and the center of fixation associated with

Answer 14

Vision loss

Question 15

Nasal retina projects to

Answer 15

Temporal VF

Question 16

Temporal retina projects

Answer 16

Nasal VF

Question 17

Inferior retina projects

Answer 17

Superior VF

Question 18

Superior retina projects into the

Answer 18

Inferior VF

Question 19

Limit of VF: nose

Answer 19

May limit or affect the nasal and inferior visual field

Question 20

What are the things limiting the VF

Answer 20

Nose
Overhanging brow
Small pupils

Question 21

Overhanging brow

Answer 21

Limits superior field

Question 22

Small pupil and VF limitation

Answer 22

A pupil less than 2.5mm in diameter can decrease the amount of light reacting the retina and can increase diffraction leading to visual distortions

Question 23

What can cause small pupils

Answer 23

Cocaine, opioids, diabetes, old people

Question 24

Sensitivity

Answer 24

The ability to respond to physical stimuli or to register small physical amounts or differences

Question 25

Threshold

Answer 25

The Manila intensity of light at which a stimulus is perceived by the visual system at a specific location in the field of vision

Question 26

Brightness

Answer 26

The attribute of visual sensation according to which an area appears to emit more or less light

Question 27

Humphrey visual field

Answer 27

Static perimetery

Question 28

Goldmann perimetry

Answer 28

Kinetic perimetry

Question 29

Two perimetry techniques used to determine the shape of the hill of vision

Answer 29

Static perimetry: Humphrey | Kinetic: Goldmann

Question 30

Gold standard for VF

Answer 30

Humphrey visual field

Question 31

Which is more sensitive, static or kinetic

Answer 31

Static

Question 32

Why is Humphrey gold standard

Answer 32

Because it is static and it is more sensitive than kinetic

Question 33

Set size and brightness, Moving from non-seeing to seeing

Answer 33

Kinetic

Question 34

Involves moving target of constant brightness horizontally, from wher its is not visible, toward the center until it intersects with the HOV

Answer 34

Kinetic

Question 35

Advantages of static

Answer 35

Best strategy for assessing the central VF Reproducible conditions Sensitive to VF defects

Question 36

Disadvantage of static

Answer 36

- does not directly plot borders of vision as single points are chosen for strategies - tedious - expensive instrumentation

Question 37

Advantages of kinetic

Answer 37

- rapidly evaluate the peripheral field - rapidly plot deep defects - quick and accurate for steep-bordered defects

Question 38

Disadvantages of kinetic

Answer 38

- difficult to recognize early field defects | - examiner has much influence on field; must be well trained or will affect the test

Question 39

The weakest stimulus which is just barely visible (50% of the time) for a particular retinal point being tested

Answer 39

Threshold

Question 40

Infra-threshold (subliminal)

Answer 40

Below threshold and not visible

Question 41

Worst disadvantage of kinetic

Answer 41

Examiner has a lot of influence on the field

Question 42

Supra-threshold (supraliminal)

Answer 42

Above threshold and visible

Question 43

Factors affecting visibility (threshold) of the stimulus

Answer 43

Size Luminance Background luminance Duration of stimulus presentation

Question 44

How does stimulus size affecting threshold

Answer 44

Increased in stimulus size with decrease threshold

Question 45

Sensitivity equals

Answer 45

Height of HOV

Question 46

Luminance and threshold

Answer 46

The average luminance os the dimmest test object that cab be seen is determined

Question 47

Background luminance and threshold

Answer 47

Webers law - when the background luminance decreases, cones adapt more quickly - controls adaptation over time - controls sensitivity profile - some VF defects are more pronounced with difference background levels - should keep both stimulus and background constant and reproducible

Question 48

Background luminance: what todo to keep it reproducible

Answer 48

Should keep both the stimulus and background constant and reproducible

Question 49

Increase in stimulus size

Answer 49

Decrease threshold secondary to spatial summation