Increasing the optic zone diameter typically makes the lens fit:

• A. True
• B. False
• C. Depends on cornea
• D. Only for flat corneas

Answer: (A)

The fit of a gas-permeable lens is driven by how the back surface mirrors the cornea and how the edge sits at the limbus. The optic zone diameter is the central area that provides vision correction, and increasing it enlarges the central region of contact on the cornea. With more central contact, the lens tends to stay more centered over the pupil and moves less with blinking, leading to a more stable, better-fitting lens. This greater centration and reduced movement is why increasing the optic zone diameter is typically associated with an improved fit. Remember that other factors like corneal curvature and the overall lens diameter still influence the final outcome, but the common effect is enhanced stability when the optic zone is larger.