Types of Lenses
Photochromic (Transitions) lenses are lenses that darken on exposure to UV radiation. Once the UV is removed (for example by walking indoors), the lenses will return to their clear state. Photochromic lenses may be made of either glass or plastic. The reason these lenses darken in sunlight but not indoors under artificial light, is that room light does not contain the UV (short wavelength light) found in sunlight. Automobile windows also block UV so these lenses will not work very well in a car. Because photochromic compounds fade back to their clear state by a thermal process, the higher the temperature, the less dark photochromic lenses will be. This thermal effect is called "temperature dependency" and prevents these devices from achieving true sunglass darkness in very hot weather. Conversely, photochromic lenses will get very dark in cold weather conditions.
Transitions lenses can help protect your eyes from glare and the harmful effects of UV rays while they’re also doing their primary job: improving your eyesight.
Transitions lenses— the Ideal choice for healthy sight: Transitions lenses give you so many benefits you need for healthy sight, including:
- Convenient protection from UV rays
- Visual quality indoors and out
- Greater comfort and relied from eyestrain and fatigue
Everyday protection: Transitions lenses protect your eyes from the harmful UV rays found in bright light. And on cloudy days, when UV light is less obvious, they provide equal protection.
Visual comfort in any light: Indoors, Transitions lenses are clear. Outdoors, in bright sunlight, they get darker, quickly and automatically. At the same time, they provide superior protection from glare, whether it’s sunny, cloudy or in between. And this means less squinting and less stress on your eyes.
Healthy sight for your kids: Children are more vulnerable to the sun’s ray than adults. That’s because typically, they spend more time outdoors than adults do during a time developing eyes are more delicate. And because the effects of sunlight are cumulative, their risk of eye damage is actually three times greater than that of adults… so they can benefit from Transitions lenses, too.
Look better, see better: With Transitions lenses, there’s a wide variety of frames, styles and prescriptions, including single – vision, bifocals, trifocals and progressives. You can also choose:
- Gray or brown color lenses.
- The UV rays that can burn your skin or cause skin cancer can also cause long- term damage to your eyes. And this may lead to serious conditions like cataracts or macular degeneration. But Transitions lenses block 100% of UVA and UVB rays to help protect your eyes and preserve your sight.