What is the back surface curvature of a lens called?

What is the back surface curvature of a lens called?

• A. Front curve
• B. Base curve
• C. Edge curve
• D. Back curve

Answer: (B)

The back surface curvature is called the base curve. This is the primary curvature of the lens’s inner surface that rests against the eye, and it’s chosen to match the corneal shape for a proper fit. The base curve is described by a radius of curvature in millimeters, with a steeper base curve (smaller radius) fitting more tightly and a flatter one (larger radius) fitting more loosely. Front surface curvature refers to the outer surface, and terms like edge curve aren’t standard for describing lens fit, so the established term for the back surface is base curve.

The back surface curvature is called the base curve. This is the primary curvature of the lens’s inner surface that rests against the eye, and it’s chosen to match the corneal shape for a proper fit. The base curve is described by a radius of curvature in millimeters, with a steeper base curve (smaller radius) fitting more tightly and a flatter one (larger radius) fitting more loosely. Front surface curvature refers to the outer surface, and terms like edge curve aren’t standard for describing lens fit, so the established term for the back surface is base curve.