Humphrey Visual Field

Question 1

Mean deviation

Answer 1

Average deviation of sensitivity calculated form each test point from age-adjusted normal population values

Generalised field loss

Question 2

Pattern standard deviation

Answer 2

Average deviation of individual test points from normal after correcting for any overall sensitivity differences e.g. global reduction from cataracts

Gives better indication of areas in the field that are relatively less sensitive than others

Question 3

Corrected pattern standard deviation

Answer 3

Takes into account short term fluctuation (testing 10 pre-selected points twice and analysing the difference)

Question 4

What to use for assessing glaucoma progression

Answer 4

Pattern standard deviation

Question 5

What is a fixation loss

Answer 5

Patient responds as if seeing light when target is displayed in blind spot

Question 6

When is there false negative

Answer 6

Patient fails to respond to supra-threshold stimulus at location that would be expected to be seen

(falling asleep, losing interest)

Question 7

When is there a false positive

Answer 7

Perimeter makes noise but no light - patient presses = false positive

Question 8

Defect on VF in glaucomatous optic nerve damage

Answer 8

Superior altitudinal defect