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
cylindrical test lenses
Lenses with cylindrical faces which are used to calibrate the axis marker and axis indicator with respect to the adjustment orientation of the rail. Note: These lenses are usually specially designed and marked.