This advanced 1.56 refractive index semi-finished lens combines bifocal functionality with intelligent photochromic technology in a single blank. Bifocal lenses seamlessly integrate distance correction (main lens) with a precision-molded reading segment (typically +1.00 to +3.00D add). Photochromic lenses contain embedded photochromic molecules that automatically darken when exposed to UV light, clearing within minutes indoors.