jan 1, 1960 - transition lense

Description:

Photochromic lenses are optical lenses that darken on exposure to specific types of light of sufficient intensity, most commonly ultraviolet (UV) radiation. In the absence of activating light the lenses return to their clear state. Photochromic lenses may be made of glass, polycarbonate, or another ... and the process was used in the first mass-produced variable tint lenses

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