curve on the back surface of the lens

curve on the back surface of the lens

• A. Base curve
• B. Front curve
• C. Back radius
• D. Optical curve

Answer: (A)

The curve on the back surface of a contact lens is called the base curve. It describes how steep or flat the inner surface that rests on the cornea is, and it’s chosen to match the curvature of the eye for a comfortable, stable fit and proper tear exchange. The base curve radius essentially controls how closely the lens hugs the corneal surface: a steeper base curve fits more tightly, a flatter one sits more loosely. The front curve refers to the outer surface of the lens, which affects optics and interaction with the eyelids, not the contact with the eye. Back radius isn’t the standard term used in fitting terminology, and optical curve isn’t a typical descriptor for the back surface.

The curve on the back surface of a contact lens is called the base curve. It describes how steep or flat the inner surface that rests on the cornea is, and it’s chosen to match the curvature of the eye for a comfortable, stable fit and proper tear exchange. The base curve radius essentially controls how closely the lens hugs the corneal surface: a steeper base curve fits more tightly, a flatter one sits more loosely. The front curve refers to the outer surface of the lens, which affects optics and interaction with the eyelids, not the contact with the eye. Back radius isn’t the standard term used in fitting terminology, and optical curve isn’t a typical descriptor for the back surface.