5.1.3 Chooses, Fits And Orders RGP

Question 1

How to choose Total diameter and BOZR for an RGP

Answer 1

TD = HVID - 2
BOZR = 1mm greater than max pupil size

Question 2

Choosing parameters based on Ks

Answer 2

• difference in Ks is 0.15-0.25, steepen by 0.05mm
• difference in Ks is 0.3-0.45, steepen by 0.1mm
• difference in Ks is 0.5 or more, bi toric/back toric/smaller diameter

Question 3

3 rules of thumb for Lens parameters

Answer 3

• every +0.50mm increase in TD, increased BOZR by 0.05mm
• every 0.05mm lens is flatter than the corneal radius = -0.25D tear lens = +0.25D OR
• every 0.05mm lens is steeper than the corneal radius = +0.25 tear lens = -0.25D OR