People who often go in and out of both indoor and outdoor environments can choose sunglasses with varicolored lenses. The color-changing lenses change in different light conditions, indoors due to the low intensity of light, the color of the lenses is lighter and the light transmission ability of the lenses is enhanced; outdoors when the intensity of light is higher, the color of the lenses becomes darker and the light blocking ability of the lenses is enhanced. Therefore, varifocal lenses can be used in both indoor and outdoor lighting environments. What are varifocal lenses? Tinted lenses are also called “photochromic lenses”. They are suitable for both indoor and outdoor use because they add silver halide chemicals to the lenses so that the lenses, which are originally transparent and colorless, will become tinted when exposed to strong light. What are the functions of tinted lenses? It is mainly used in the open field, snow and indoor workplaces with strong light sources to prevent eye damage from sunlight, ultraviolet light and glare. In layman’s terms, the silver halide inside becomes black silver particles when exposed to strong light.