A lens made of a material that changes colour as a result of exposure to UV light and heat.
• (a.) Alt. of Photochromatic
photochromic 1. A reference to a material, such as certain glass or film, which turns dark when exposed to light and returns to its normal transparency with the removal of the light source. 2. Relating to, or characterized by, changing color as a result of exposure to incident radiation.
Used in sunglasses and goggles. Refers to lenses that adapt to external light conditions.