Meet the uvex variotronic: a pair of bike glasses with a photocell light sensor that automatically adapts its tint to the lighting condition around you in less than 0.1 seconds. This can be done automatically or with the push of a button. Here is how these glasses work:
a laminate of liquid crystals with electrochromatic activation through by a photocell light sensor. It reacts to the current intensity of light and regulates the tint of the glass in a split second.
The uvex variotronic is available for cyclists and mountain bikers. More information is available here.