For Ks greater than 45.00 D, we often select a base curve that is

For Ks greater than 45.00 D, we often select a base curve that is

• A. Flat
• B. Slightly steep
• C. Steep
• D. Very flat

Answer: (C)

A higher Ks means a steeper cornea—the diopter value increases as the radius of curvature decreases. To fit that contour well, you select a base curve that is steeper (smaller radius) so the lens backside matches the corneal shape. This yields a stable, centered fit with proper tear film play. If the base curve were flat, the lens would ride on the eye, move too much, and fit poorly. A base curve that’s too steep can cause too much bearing, but the goal for Ks above 45.00 D is to use a steeper base curve to align with the steeper cornea.

A higher Ks means a steeper cornea—the diopter value increases as the radius of curvature decreases. To fit that contour well, you select a base curve that is steeper (smaller radius) so the lens backside matches the corneal shape. This yields a stable, centered fit with proper tear film play. If the base curve were flat, the lens would ride on the eye, move too much, and fit poorly. A base curve that’s too steep can cause too much bearing, but the goal for Ks above 45.00 D is to use a steeper base curve to align with the steeper cornea.