If you don’t want the expense of buying a second pair of glasses or simply want the convenience of not having to switch pairs, photochromic lenses may be the answer to owning prescription sunglasses as well as regular eyeglasses. Photochromic lenses react when exposed to UV light, darkening within minutes or even seconds to allow you to see comfortably in bright sunlight and many also offer UV protection.
You can get photochromic lenses in virtually any type of material. They change from clear or slightly tinted to a darker shade, although the colour, amount of tint and the time it takes for the lens to fully darken will vary from brand to brand. Photochromic lenses are not all the same. Read on to find out about the different kinds available.
Photo Gray Lenses
Corning Medical Optics invented the original photochromic lenses over thirty-five years ago. These lenses, called photo gray and photo brown are still available today, but they are not without their drawbacks.
The final tint of the lens depends on the strength of the prescription and the stronger the prescription, the darker the lens will be. If your eyes require different amounts of vision correction, the weaker eye will end up with a darker lens that the other eye and you may notice uneven colour within a lens. The thicker areas of the lens will be darker than the rest.
Thin & Dark Lenses
There is also a newer photochromic lens by Corning called Thin & Dark, which is a glass lens that is thinner and lighter and can change from clear to dark in about sixty seconds. Thin & Dark lenses are available in both brown and gray.
Corning also offers SunSensors lenses that are as thin as the glass ones but even lighter. Thin & Dark glass lenses still have issues with colour distribution but this problem is almost completely solved with the plastic SunSensors, no matter what the prescription strength is.
Transitions Optical makes Transitions lenses, one of the most versatile photochromic lenses on the market. These lenses can be made from a variety of lens materials, including plastics and polycarbonate and made for almost every prescription and design. Transitions lenses turn from light to dark and back again very quickly and provide 100 percent UV protection.
You can also get photochromic lenses by Transitions called Drivewear. These lenses are designed to work inside cars as well as outdoors. The sun’s UV rays are needed to trigger sun protection, but car windshields block these rays. Drivewear lenses react to visible light, as well, making it possible to drive without squinting and they are also polarized to reduce glare.