Photochromic lenses that allow you to walk from inside to outside without putting on UV-filtering lenses have been around for decades. But the technology is just making its way to contacts.
Traditionally, these light-to-dark lenses have been constructed by coating a normal lens with a photochromic dye. When UV light hits the dye, the individual molecules expand, darkening the lens and absorbing light. Coating contacts, however, doesn't work so well.
So researchers in Singapore have laced contacts with a matrix on nano tunnels filled with these photochromic dyes. Not only has the team been successful in producing transition contacts; these contacts darken in the presence of UV light faster than standard lenses (just 10-20 seconds).
Researchers are now working on isolating the photochromic material to just the corneal region of the eye, granting you all of the UV filtering without turning your entire iris black.
But until they graft the timeless style of a Wayfarer onto my eyeball, I'll pass. [Technology Review and image]