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.
Transitions scientists continuously strive to improve our technology and create formulations that find the perfect balance between UV light and the temperature of the lenses. In fact, our newest Transitions Signature™ lenses are more responsive than ever before – they get 15% to 21% darker across temperatures, and even in indirect light.. It’s one of many reasons we are the most recommended photochromic lens brand worldwide.