The word photochromic comes from two Greek words; photo meaning light and chroma meaning color. Photochromic lenses change color when exposed to light. Some other names for photochromic lenses are Light Adaptive, Variable Tint Lenses, Photochromatic, and some people call them by the popular name brand "Transitions." You can get photochromic lenses that change all the way from completely clear to dark sunglasses, but Photochromic Sunglasses are just for outdoor wear. If you are interested in photochromic lenses for your everyday, clear prescription glasses, you can find more information about Transitions lenses here.
Sunglasses with photochromic lenses start from an already relatively dark tint and get even darker based on the light conditions. Some manufacturers also call these kind of lenses "Drivewear" and popular brands that make use of photochromic technology in their sunglasses are Ray-Ban, Persol, Oakley, Serengeti, and Tag Heuer..
Photochromic sunglasses do not darken when exposed to ANY kind of light. There are molecules in the lenses that change shape when exposed to Ultraviolet (UV) Radiation. The change in the molecules allows them to absorb more light and causes the lenses to darken. This technology can be used in lenses of different materials, but most commonly they are made from glass or polycarbonate. The more UV Radiation the lenses are exposed to, the darker they become. Most photochromic sunglass lenses will begin to significantly darken within about a minute and may continue to get darker for 15 more minutes. They normally take a little bit longer to return to their lighter tinted state.
Because UV rays can penetrate clouds, your photochromic sunglasses will still darken on an overcast day. Another thing to be aware of is that the windows and windshields of many cars are equipped with UV filters, which causes photochromic lenses to be less effective.
If you have questions about ordering Photochromic Sunglasses online, be assured FramesDirect.com have plenty of resources to make the process easy.
Contact one of our experienced opticians if you have any questions about photochromic sunglasses.
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