glossary

The grinding and polishing of a lens surface.

A group of genetic eye conditions leading to chronic retinal degeneration, accompanied by abnormal deposits of pigment. The disease causes a progressive decrease in peripheral or side vision. Associated with night blindness, loss of peripheral vision, tunnel vision, decreased acuity, lack of depth perception, retinal scarring, and photophobia.

Ophthalmic lens that utilizes a steepening of curves to incorporate corrections for distance vision through intermediate range, to near vision (usually in lower part of lens), with smooth transitions and no bifocal demarcation line.