Over time, exposure to UV light can damage the cornea, the lens of the eye, and the eyelids. Sunglasses can help protect the eyes from the harmful rays of the sun. However, people who wear prescription eyeglasses are not always willing to carry around a second pair of prescription lenses to wear outdoors. To tackle this problem, eyeglass manufacturers have introduced photocromic eyewear, a type of specialty eyewear designed to transition from clear to dark when exposed to sunlight.
What are photocromic eyeglasses?
Photocromic eyeglasses are prescription glasses that are designed to adjust to different light surroundings. Also known as transition lenses, these clear eyeglasses gradually darken when exposed to light. Once the UV light is removed, the lenses lose their tint and become clear again.
Transitional lenses are embedded with molecules that are able to change shape when they are exposed to UV light. As the molecules absorb the UV rays, the lenses begin to darken. In the absence of UV rays, the molecules resume their natural shape and lose their ability to absorb light, causing the lenses to become clear. The more intense the UV rays, the darker the lenses will become. The transition takes anywhere from a few seconds to several minutes.
Why are photocromic eyeglasses worn?
Photocromic lenses solve a major problem for people who wear prescription glasses. They no longer have to invest in and carry around two pairs of prescription lenses for indoor and outdoor light conditions. With photocromic lenses, there is no switching back and forth between prescription eyeglasses and prescription sunglasses.
Benefits of photocromic eyeglasses
Photocromic eyeglasses provide a major convenience for eyeglass wearers, eliminating the need to tote around a pair of prescription sunglasses to wear outdoors. Another benefit is protection from UV light. Even the slightest change in the intensity of UV light exposure will cause the lenses to darken appropriately and shield the eyes from harmful rays.
Problems associated with photocromic eyeglasses
Photocromic eyeglasses do have a few drawbacks. They generally do not work well when driving because the car's windshield blocks UV light; as a result, there is nothing to trigger the lenses to darken to block glare. Another complaint about photocromic lenses is that they do not adjust immediately to light. It can take up to two minutes for the lenses to completely darken outdoors or clear indoors.
To learn more about transitional lenses, schedule an appointment with your optometrist.