Photochromic lenses, also known as light-adaptive lenses or variable tint lenses, are a type of eyeglass lenses that remain clear indoors and automatically darken when exposed to sunlight. The most well-known brand of photochromic lenses in the United States is Transitions Lenses, leading some people, including eye care practitioners, to refer to all photochromic lenses as "Transitions lenses." However, there are other brands available as well. These lenses darken when activated by the sun's ultraviolet (UV) radiation, including on overcast days since UV rays can penetrate clouds.
Typically, photochromic lenses do not darken inside a vehicle due to the UV-blocking properties of the windshield glass. However, advancements in technology have led to some photochromic lenses that can activate with both UV and visible light, providing partial darkening behind the windshield. It's best to consult with your optometrist for specific details.
Photochromic lenses are available in various lens materials and designs, including high-index lenses, bifocals, and progressive lenses. One of the added benefits of these lenses is that they offer 100% protection against the sun's harmful UVA and UVB rays. Considering that lifetime exposure to sunlight and UV radiation is associated with cataracts later in life, photochromic lenses are a good choice for both children's eyewear and adult eyeglasses. Polycarbonate is the safest lens material for kids, offering superior impact resistance compared to other materials.
To enhance the performance of photochromic lenses further, adding an anti-reflective (AR) coating is recommended. AR coating allows more light to pass through the lenses, resulting in sharper vision in low-light conditions, such as driving at night. Additionally, it eliminates bothersome reflections of sunlight and other light sources from the backside of the lenses in bright conditions.
While photochromic lenses may have a higher cost compared to clear lenses, they provide the convenience of eliminating the need to carry a separate pair of prescription sunglasses at all times.
For outdoor wear, photochromic sunglasses are available. Although they are not as clear indoors as other photochromic lenses, they offer extra comfort in bright sunlight and while driving. Transitions Optical has introduced Transitions Drivewear, polarized adaptive lenses specifically designed for driving. These lenses adapt to changing light conditions inside a vehicle, enhance contrast, and improve visual performance.
Transitions Optical also incorporates its photochromic technology into a range of adaptive sunglasses, motorcycle and bike helmet shields, and snow goggles. These products enhance visual performance during outdoor activities, providing comfort in varying light conditions and enhancing contrast. They offer the convenience of not needing to switch products as the light changes. Notable brands such as Bell Helmets, Shoei, Oakley, Nike, and Dragon Alliance feature Transitions Optical's photochromic technology in their products, offering a variety of tint and color options, including clear to dark lenses, dark to darker lenses, and clear to dark helmet shields. Additionally, the photochromic performance of products designed for snowboarding and winter activities is optimized for cold temperatures.
Aside from protecting the eyes from glare outdoors, photochromic lenses also offer an important benefit by helping to shield the eyes from harmful blue light. Blue light contributes to digital eye strain and oxidative stress in the retina. Prolonged exposure to harmful blue light from sunlight and digital device screens may potentially increase the risk of macular degeneration and other eye problems later in life. Photochromic lenses, such as Transitions Signature, Transitions Vantage, and Transitions XTRActive, provide varying levels of protection against harmful blue light both indoors and outdoors when compared to clear lenses.
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