C
- carrier
- central field
- centration distance CD
- centration error of the instrument
- centration point CP
- clear lens
- coated lens
- combination frame
- concave lens
- condensing lens
- continuously-indicating focimeter
- contrast
- converging lens
- convex lens
- corneal plane
- Corneal Refraction
- corrective lens
- curved-form lens
- curved-top bifocal
- curved-top segment
- cylinder
- cylinder axis
- cylindrical lens
- cylindrical power
- cylindrical surface
- cylindrical test lenses
centration point CP
Point at which the optical centre, design reference point or fitting point is to be located in the absence of any prescribed or thinning prism, or after any such prism has been neutralized.