Photochromic Lenses

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Photochromic lenses are an eyeglass lens type that changes the tint of the lens to adhere to light conditions. This eyeglass lens was designed to shield the wearer's eyes from the sun without the wearer having to change from eyeglasses to sunglasses. Using chemical alterations, the lens material reacts to UV rays by darkening the lens when the UV light is high, and returning the lens to clear when it's not exposed to UV rays from the sun. Photochromic Lenses can come in glass, plastic, polycarbonate, or high-index material. Depending on the type of material, photochromic lenses utilize microcrystalline or photochromic molecules to transition between dark and clear states.

Certain brands, like Transitions, block 100% of all UV light regardless if the lens is clear or dark. The transitional state begins the exact moment that the lens comes in contact with UV light. Transitions lenses can be used with almost any frame brand, including Calvin Klein, Dolce and Gabbana, and Nautica.

The transition stages generally take about 15 minutes for each total transition, but the majority of the transition takes place in less than 3 minutes of being exposed or unexposed to UV light. Because the lens relies on thermal condition for transition, higher temperatures will prevent the lens from reaching full darkness. This means that the lens will become very dark in cold weather, when the transition is not altered by a high temperature.

Since most automobiles have a UV protection windshield, photochromic lenses do not darken effectively inside a motor vehicle unless the lenses are equipped with Drivewear.

Photochromic lenses can also be equipped with XTRActive, for eyeglass wearers who are more sensitive to light or spend a lot of time outdoors.