subject: Photochromic Transition Lenses [print this page] Transition lenses are special lenses that kill two birds with one stone. As its name reflects, Transition lenses can transit from light to dark when exposed to UV light. Since transition is needed between bright and dark conditions, Transition lenses are mostly seen in Transition sunglasses. With the advancements in photochromic technologies, Transition lenses are now available in almost every lens materials and designs, such as high-index, polycarbonate and bifocals and progressives.
Transition lenses have special photochromic dyes in them, which activate while exposing to UV rays and fade back to clear while UV light is reduced. In this way, the tint levels of Transition sunglasses adjust to offer the right tint in accordance with the light condition. This feature of Transition lenses provides a constant 100% UV protection, which is hardly achieved by ordinary sunglasses.
Transition sunglasses are particularly helpful for those with light sensitivities. Transition lenses begin to darken once exposed to UV light, and become the darkest at the height of UV ray intensity. If you walk into a room thus UV rays are removed, the sunglasses will return to clear again. Although some Transition sunglasses users say that the transition process actually costs several minutes, it is really smooth that wearers may even be unaware.
Since children are more susceptible to UV radiation due to their developing eyes, they can benefit more from Transition sunglasses than adults. Statistics show that over 80% of the total lifetime UV exposure happens before 18. So that Transition lenses are essential to provide enough protection for teenagers. Especially, Transition sunglasses for children should be made of polycarbonate.
