Photochromic lenses are lenses that darken on exposure to specific types of light, most commonly ultraviolet (UV) radiation. Once the light source is removed (for example by walking indoors), the lenses will gradually return to their clear state. Photochromic lenses may be made of glass, polycarbonate, or another plastic. Photochromatic lenses con...
A light-sensitive spectacle lens that reduces light transmission in sunlight and increases transmission in reduced light. ... (05 Mar 2000) ... 
Type: Term Definitions: 1. a light-sensitive spectacle lens that reduces light transmission in sunlight and increases transmission in reduced light.
photochromic lens A light-sensitive spectacle lens that reduces light transmission in sunlight and increases transmission in reduced light.
[Eye and Face Protection] a lens designed to darken when exposed to sunlight and fade when removed from the sunlight.