A decrease in the base curve diopter leads to a radius that is

A decrease in the base curve diopter leads to a radius that is

• A. Radius increases
• B. Radius decreases
• C. Radius stays the same
• D. Cannot determine

Answer: (A)

The base curve diopter and the radius of curvature are inversely related: D = 1/r (with r in meters). When the base curve diopter decreases, the radius increases. A flatter, gentler curve means a larger radius, so lowering the diopter makes the lens back surface have a larger radius of curvature. For example, dropping from about 50 D to 40 D changes the radius from 0.02 m to 0.025 m. Therefore, the radius increases.

The base curve diopter and the radius of curvature are inversely related: D = 1/r (with r in meters). When the base curve diopter decreases, the radius increases. A flatter, gentler curve means a larger radius, so lowering the diopter makes the lens back surface have a larger radius of curvature. For example, dropping from about 50 D to 40 D changes the radius from 0.02 m to 0.025 m. Therefore, the radius increases.