What term describes the GP lens cornea-fitting relationship?

• A. the refractive matching principle
• B. the cornea fitting relationship ('on k')
• C. the tear-dispersion mechanism
• D. the optical alignment rule

Answer: (B)

The term describes how a GP lens fits relative to the cornea is called “on-K” (on Keratometry). It means the base curve of the lens is chosen to match the corneal curvature measured by keratometry, so the lens sits directly on the cornea rather than vaulting over it or bearing excessively in a single area. This on-K relationship gives predictable centration and comfortable movement while preserving good optical quality. The other options refer to refractive power, tear-film dynamics, or nonstandard terminology and don’t capture the specific fit relationship between the GP lens and the cornea.