For a tricurve GP lens, which curves would you expect to see?

• A. BC + peripheral curve
• B. BC + intermediate curve + peripheral curve
• C. BC only
• D. BC + 2 intermediate curves

Answer: (B)

The back surface of a tricurve GP lens is made with three distinct curved segments: the base curve, an intermediate curve, and a peripheral (edge) curve. The base curve sits at the center and sets the core fit where the lens contacts the cornea. The intermediate curve provides a smooth transition between the center and the edge, refining how the lens vaults over the mid-periphery and how tear film is distributed. The peripheral curve shapes the posterior edge to control edge lift, lid interaction, and tear exchange.

Because the term “tricurve” specifies three posterior-surface curves, you should expect to see all three: base curve, intermediate curve, and peripheral curve. Designs with only the base curve, or with base plus peripheral only, or with extra intermediate curves but without the proper peripheral curve, would be a different back-surface configuration.