noun
photochromic
Describes materials, especially lenses, that darken when exposed to light and return to clear when the light is removed.
このメガネはフォトクロミックレンズを使っている。
These glasses use photochromic lenses.
フォトクロミック素材は紫外線で色が変わる。
Photochromic materials change color with ultraviolet light.
Borrowed from English 'photochromic', from 'photo-' (light) and 'chromic' (color).