With photochromic lenses, the intensity of colour changes according to the level of sunlight; becoming darker in bright conditions and fading to clear in darker conditions.  
Hoya's high quality photochromic lenses can be worn throughout the day, with no need to switch to and from regular sunglasses. The colours are carefully selected for increasing contrast and to most effectively eliminate the blinding effects of the sun.

Suntech is a photochromic top layer which is applied to the front surfaced of the lens using Hoya's high performance spin coating technology.
Using advanced, fully computer-controlled equipment, the photochromic material is applied to the lens surface in an exceptionally accurate process. During the follow up treatment, special emphasis is placed on the adhesion to Hoya's Eynoa 1.67 and Eyas 1.60 lens materials. this forming a reliable composite with a long life span.