AC/A

Question 0

.Change Rx -> Change phoria

Answer 0

Add +
(overminus -> less minus to correct myope)
(underplus -> more plus to correct hyperope)

-> Relax acc -> Relax acc converg
-> Move eyes outward = Less eso (More exo)
Change at distance AND near

Add -
(underminus -> more minus to correct myope)
(overplus -> less plus to correct hyperope)

-> Engage acc -> Engage acc converg
-> Move eyes inward = Less exo (More eso)
Change at near only

Question 1

.AC/A - Definition

Answer 1

Change in acc converg for every D change in acc

Question 4

.Relationship btwn AC/A and change in Rx

Answer 4

AC/A = Change in phoria / Change in Rx

Question 5

.Why calculated AC/A is typically > measured (gradient) AC/A

Answer 5

Calc AC/A
Change in proximal convergence

Measured (gradient) AC/A
Lag of acc (typically ~ 0.50D)

Question 6

.Calculated AC/A - Equation

Answer 6

= PD + (HN - HD)/Acc,
where PD = distance PD (in cm), HN and HD = near and distance phorias (where exo = -), Acc = at near (in D) = 1/distance (of near target, in m)

Question 7

.Expected AC/A

Answer 7

Gradient
4/1
(range 3/1 - 5/1)

Calculated
5/1
(range 4/1 - 6/1)