Posted on 4th Aug 2011 @ 3:22 PM

Transition lenses have special dyes that allow them to self-adjust when the amount of available light changes. These patented dyes are photochromic; they are affected when exposed to ultraviolet (UV) rays produced by the sun. Specifically, the exposure of these lenses to UV rays causes the lenses to darken. As the presence of UV rays increases, the lenses change accordingly and become darker.

The lenses tend to undergo the most change during the day. When you step outside on a sunny day, lenses automatically become clearer. They ultimately adjust to allow a suitable amount of light to enter your eyes. This is a gradual process and practically unnoticeable to the wearer. However, glasses tend to darken more rapidly than lighten. At night or when indoors, when UV rays are no longer present, the lenses are as clear as regular reading glasses.

Transitions lenses do not work well inside a car as most windscreens use UV blockers and this prevents the lenses form tinting. Tip if your lenses over time are holding a residual tint simply place them into the freezer for about 1 minute and this resets the reaction material.