Photochromic lenses are spectacle lenses that automatically darken when activated by certain wavelengths of light and become clearer again when that activation decreases. They are often called light-reactive lenses. “Transitions” is a brand name, not the generic name for every photochromic lens.
Photochromic materials contain molecules that change structure when exposed to activating light. That change increases light absorption and darkens the lens. When the activating light is reduced, the molecules return toward their original state and the lens becomes clearer.
UV protection is an important eyewear feature. The National Eye Institute recommends sunglasses that block 99 to 100 percent of UVA and UVB radiation or carry a UV400 rating. Many modern photochromic lenses are designed with UV protection, but the exact specification should be verified for the product being dispensed.
Traditional photochromic lenses rely heavily on ultraviolet light for activation. Vehicle windshields block much of the UV that would normally trigger darkening, so some lenses do not become as dark behind the windshield as they do outdoors. Newer product designs may use additional visible-light activation, but performance varies by brand and should not be generalized.
Neither option is universally better. Photochromic lenses are convenient for frequent transitions, while prescription sunglasses can provide a consistent outdoor tint and can be combined with polarization for glare-heavy activities such as driving or time near water. Some people keep both.
Photochromic lenses automatically change tint in response to activating light. They can provide convenient outdoor light control and prescription correction in one pair, but activation speed, darkness and in-car performance vary by product. Verify the UV specification and product claims before purchase.
Need help choosing eyewear or contact lenses? Contact Eye Gallery by Garen Oganni at its Beverly Hills location to ask about current products, optical services and appointment availability. For medical concerns, request evaluation by the appropriate licensed eye care professional.
Are photochromic lenses the same as Transitions lenses?
Transitions is a trademarked brand of photochromic lenses. Photochromic or light-reactive is the generic category.
Do photochromic lenses block UV?
Many do, but UV performance should be verified for the specific product. NEI recommends 99 to 100 percent UVA and UVB protection or UV400 for sunglasses.
Why don’t my photochromic lenses get dark in the car?
Many traditional designs activate mainly with UV light, and windshields block much of that UV. Product performance varies.
Are photochromic lenses polarized?
Not necessarily. Photochromic and polarization are separate technologies, although some products may combine them.
Can photochromic lenses be made with a prescription?
Yes. They are commonly available in many prescription lens designs, subject to the range offered by the selected manufacturer and prescription.
