The Institute of nanotechnology from Singapore presents a few lenses that darken with sunlight

This advance in the world of materials of contact lenses has been announced by the Institute for Bioengineering and Nanotechnology of Singapore. It basically consists of a few lenses that are completely transparent in normal light conditions, but darken as the crystals of the sunglasses when there is intense light. The result is lenses to protect the eyes from ultraviolet rays like conventional glasses.

The novelty is a polymer that is composed of a kind of nano-tunnel in which there is a compound which reacts to sunlight. When ultraviolet light it shines on them they darken, going back to original shape and appearance when the light of the Sun. An important aspect of these 'transition lenses' has to do with the speed with which react to light: if they were too slow would not be useful. In these lenses the transition time is between 10 and 20 seconds, much faster than in the glasses of glass and other materials where they are sometimes needed several minutes.

For the moment they work without problems in rabbits and soon will begin tests in humans, for it might be marketed next year.