vision science midterm 2

all male audience of 500. How many color deficients?

25 deuteranomalous, 5 deutans, 5 protans, 5 protanomalous.

Tritan color deficiency

1. is very rare

2. can be detected with D15 or HRR

3. often signifies ocular, systemic or neurological disease

Gene tests indicate 2 cone photopigments : 426 and 530. DX ???

Protanope

Retinal densitometry with a 1-2 deg target in protanope reveals :

1. M cone density

2. Chlorolabe sensitivity

3. Green Cone absorption

Retinal densitometry with a 1-2 deg target in deuteranope reveals :

1. Red Cone absorption

2. L cone absorption

3. Red cone sensitivity

A CIE value of x=0.33, y=0.33 :

1. appears white

2. is in the middle of the CIE diagram

3. has a z value of 0.33

4. might appear gray rather than white

Rayleigh match by normal. Deuteranomal :

1. sees the top red-green mixture field as too red

2. adds more green to the top field to match to yellow

3. the pt’s midpoint has shifted toward green

4. the wider the matching range, the more severe the deficiency

Rayleigh match by normal. Protanormal :

1. sees the top R-G mixture field as too green

2. adds more than normal amount of red to top field match bottom

3. has midpoint matching range shifted toward red

4. would show expanded matching range if deficiency is severe

Acquired color deficiency :

can be a sensitive early sign of disease

Log MAR VA for OD 20/20, OS 20/80

OD 0.0, OS 0.6

Select 3 Log MAR and spatial frequncies paired correctly

1. 0.0, 30 CPD

2. -0.3, 60 CPD

3. 0.3, 120 CPD

Contact threshold is 1%. CS and log CS would be?

100 ; 2

log MAR is -0.6 VA, what is the spatial frequency cut-off

20/5 ; 120 cycles/deg

Patient fails HRR screening. Log MAR is 0.3 without rx. What is your diagnosis?

color deficiency and myopia

Log CS is 2.3. Contrast threshold is:

0.5%

On projected chart etter is 45 cd/m2, background is 55 cd/m2. If room lights are turned on adding 15 cd/m2 to letter and

background, then what is letter contrast before and after room lights turned on?

10%, 7.7%

On projected chart etter is 45 cd/m2, background is 55 cd/m2. If room lights are turned on adding 15 cd/m2 to letter and

background, then what is letter contrast before and after room lights turned on?

Remains the same

A 12-year-old female gets 7 of 14 correct on the Ishihara PIP and you conclude that she has hereditary color deficiency (CVD).

Which statement is INCORRECT?

The D15 is superior to the HRR to confirm her CVD.

Given 200 Hz flickering light; on period=2msec 100 cd/m2; off period=3 msec 0 cd/m2. Which steady (nonflickering) light will

match this stimulus in brightness?

40 cd/m2

OD 20/20-3, OS 2040+2. Log MAR

OD 0.06, OS 0.26

Mom is color normal, Dad is color deficient; son is color deficient; he has a sister. Which is incorrect?

If Dad is a protanope, then son will make multiple crossings on D15.

If constrast threshold is 0.25% (0.0025), then CS and log CS are:

400, 2.6

A seitan dichromat (deuteranope) will most likely :

make deutan crossing errors on the D15