The Benefits of Photochromic Lenses
Photochromic lenses react when in direct contact with UV light and offer a great alternative to switching between glasses and prescription sunglasses. In brighter conditions, the lenses will darken and as conditions become darker, the lenses will once again become clear.
What are Photochromic Lenses?
Photochromic lenses are glasses lenses that react to different levels of UV light. When exposed to bright light on a sunny day, molecules in the lens react and become darker, offering protection from the sun’s radiation. As light levels decrease, the molecules go back to their original state and become transparent once again. Photochromic lenses only react when exposed directly to UV light, meaning that in the office or home environment, they will remain clear.
How do Photochromic lenses work?
Photochromic lenses are coated with special molecules, such as silver chloride, that change shape and absorb light when exposed to UV rays. It is this reaction that causes them to darken in sunlight. When taken away from UV light, the process reverses, causing the lenses to gradually become lighter. The lenses typically take around 15 minutes to fully darken, although some change will be seen within the first minute.
Photochromic sunglasses are normal sunglasses that are fitted with photochromic lenses. Their lenses behave the same way and will be transparent indoors and become dark outdoors. Some photochromic sunglasses lenses, however, do come with dark lenses and gradually become darker. These are typically worn for outdoors use only.
It is important to note that some photochromic lenses may not be suitable for driving. This is because car windshields are coated with a UV-blocking layer, which will prevent your photochromic lenses from adjusting to light conditions inside your car.
Transitions lenses are the commercial term for photochromic lenses. The term "transitions lenses" refers only to photochromic lenses manufactured by Essilor. Any other brand of photochromic lenses, manufactured by HKO, Hoya, or ZEISS, for example, will operate and work in exactly the same way.