The smaller optic zone diameter results in the lens fit being:

• A. Steeper
• B. Depends on iris size
• C. No change
• D. Flatter

Answer: (D)

The fit of a gas-permeable lens is governed by the lens’s sagittal height, or how much the lens curves away from the cornea. The optic zone is the central part where the curvature is most pronounced. If you decrease the optic zone diameter, there’s less of the lens surface carrying that tighter central curvature. The remaining surface, which is formed by the peripheral curves, has a flatter contour. As a result, the overall posterior surface of the lens becomes flatter on the eye, producing a flatter fit.