Photochromic lenses are sometimes referred to as transition lenses, but there’s really no difference between the two except for the name. Transitions was the first mainstream brand of photochromic lenses available, so the name became synonymous with the self-darkening lenses. Whether you call them photochromic or Transitions, these eyeglass lenses automatically darken to a hue resembling sunglasses in the presence of sunlight, then become clear again when indoors. The color changing effect is a result of a chemical responding to the presence or absence of ultraviolet light.

How Photochromic Lenses Work

Photochromic lenses work because of trace amounts of silver chloride that is embedded in the lenses themselves. These molecules are activated by UV radiation, which is present in sunlight, causing the silver molecules to gain an electron from the chloride to become silver metal. Another molecule, copper chloride, strips the silver of its chloride electron and helps the lenses return to their original clear condition.

The rays can penetrate through clouds and certain types of glass, which allows the lenses to darken, even on cloudy days or sometimes even when the wearer is driving or indoors. Once activated, the chemical response shields eyes from 100 percent of harmful UV rays from the sun, much light traditional sunglasses do.

Photochromic technology is also used in car windshields. This helps drivers see in sunny conditions and also helps filter UV rays entering a car to preserve the interior of the vehicle and protect drivers from sunburns while driving. Unlike in photochromic eyeglasses, the glass in a windshield is designed to not darken in the presence of UV rays, staying completely clear.

Photochromic Eyeglasses

Photochromic lenses are a popular choice for eyeglasses because of their exception performance in any light conditions. Many people add an anti-reflective coating to their photochromic lenses to further enhance their performance by improving vision in low-light conditions like nighttime driving.

Photochromic eyeglasses cost more than regular eyeglasses, but they perform like both traditional eyeglasses and sunglasses, making the added cost well worth it to many wearers. By choosing photochromic eyeglasses, wearers can enjoy the benefits of sunglasses without having to carry extra eyewear with them.

Types of Photochromic Lenses

There are different types of photochromic lenses available, including lenses by popular brands like Transitions. Advances in photochromic lens technology allow for faster transitions, greater light sensitivity and better UV protection. Some even have a slight tint for indoor use, protecting against digital device screens, fluorescent lights and other indoor hazards. Your lifestyle and budget will determine which types of photochromic lenses are right for you.

Photochromic lenses are also available in sunglasses form. While standard photochromic lenses darken to resemble sunglasses, photochromic sunglasses are always at least slightly darkened as they are made specifically for outdoor wear. These types of lenses will not clear up completely and are designed for people who work outdoors, participate in sports like cycling or do a lot of long-distance driving.

If you’re in the market for a new pair of photochromic or Transitions lenses, Payne Glasses can help. We can pair your favorite eyeglass frames with the lens of your choice for optimal protection and comfort. Shop our huge selection online and find the right eyewear for any need.