I recently went to the optometrist and got a new prescription for glasses. This time I decided to get transition lenses , which will be the first time that I have worn them.
Transition or “photochromic” glass was originally developed in the 1960s by Donald Stookey, a chemist at Corning Glass Works and a prolific inventor. webpage
When photochromic lenses are exposed to UV light, trillions of photochromic molecules in the lens begin to change structure. This reaction is what causes the lenses to darken. webpage
The molecules in photochromic technology work by reacting to UV light. However, temperature can have an effect on the reaction time of the molecules. When the lenses become cold the molecules begin to move slowly. This means that it will take somewhat longer for the lenses to adapt from dark to clear. When the lenses become warm the molecules speed up and become more reactive. This means that they will fade back faster. It can also mean that if you’re outside on a hot sunny day, but sitting in the shade, your lenses will be quicker to detect the diminished UV rays and lighten in color. Whereas, if you are outside on a sunny day in a cold climate, and then move into the shade, your lenses will adjust more slowly than they would in a warm climate.
>A trick to speed up the transition from dark to clear is to put the glasses under warm water.