CLOCK DIAL AND JCC

Question 1

how to calculate fogging lens for clock dial?

Answer 1

1/2 A + 0.5 DS ( whole thing in plus sphere)
*note that if VA is 6/6 or better, fogging lens is +0.50DS

Astig: L/9
where L is the snellen denominator of BVS VA

Question 2

why do we need fogging lens?

Answer 2

shift the COLC in front of the retina to bring out any hidden astig

Question 3

what are the instructions given for CD?

Answer 3

can you tell me which lines appear the darkest and clearest

Question 4

how to find axis of cyl?

Answer 4

take the lesser hour x 30

Question 5

how to find cyl power and what is the end pt?

Answer 5

add cyl lenses

all lines are equally clear

Question 6

what results should be obtained from duochrome before JCC?

Answer 6

1 step on green or R=G

Question 7

what is the target for JCC?

Answer 7

cluster of dots

if VA worse than 6/12, use rounded letters eg O or C

Question 8

how to determine axis in JCC

Answer 8

1. put handle at axis found in BVS
2. i am gg to show u 2 lenses, tell me which lens makes the dots rounder and clearer.
3. adjust handle towards the red line by 20-10-5 deg
4. repeat until end pt (both lenses are same)

Question 9

how to determine power in JCC? what is the end point?

Answer 9

1. place the axis found in JCC into trial frame
2. align the red or black markings to the axis
3. i am gg to show u 2 lenses, tell me which lens makes the dots rounder and clearer.
   4.if px prefers black, take away 0.25DC
   if px prefers red, add -0.25 DC

end pt: when both lenses are same

Question 10

when to carry out bracketing?

Answer 10

done when no cyl is found in ret

Question 11

what is the general rule for JCC? (about adding the lenses)

Answer 11

for every +/- 0.50 DC added, we put +/- 0.25 DS in oppo sign