Cl behaviour, effect of spec - cl

Question 1

CL behaviour in the eye

Answer 1

related closely to CL sag

• Higher the sag the tighter the grip on cornea (higher sag = good concentration)

Question 2

what is SAG

Answer 2

sagittal height/ depth -vertical space between a curved surface from the apex of the surface to a horizontal line circumscribed by lens diameter

Question 3

what is the rs between bc, diameter and sag

Answer 3

• To increase sag, decrease BC(steepened)
• To increase sag, increase diameter
• To maintain sag: offset the effect

Question 4

what is the effect of switching spec to cl

Answer 4

1. change of retinal image size
2. change accommodation demand
3. change converge demand

Question 5

what is the change of retinal image size for myope

Answer 5

lens is less effective as the VD is decreasing, the minification effect will be lesser with smaller VD hence, switching myope to cl will make everything myope see bigger opp for hyperope

Question 6

what is the change in accommodation demand in myope

Answer 6

(A=-L(1+2dK))

- Myope = accommodate more opp for hyperope

Question 7

what is the change in convergence demand in myope

Answer 7

• Myope converge more = the base in effect is not present in the cl more work is done opp for hyperope