If you wear prescription glasses and are tired of switching back and forth between your normal glasses and prescription sunglasses, photochromic lenses, also known as Transition lenses, could be the answer. These lenses adjust to allow you to see clearly under changes in lighting conditions.
Before buying, you should be aware of the pros and cons of Transition lenses to be sure they’re right for your lifestyle.
How they work
When exposed to ultraviolet light, the lenses darken to look like sunglasses. When you go back indoors, or at night, the lenses revert back to their original clear state. These lenses only darken in response to the short wave lengths in sunlight, so indoor lights won’t trigger them.
When exposed to UV light, trillions of photochromic molecules in the lenses begin to change structure and this is what causes them to darken. These molecules constantly and smoothly recalibrate so that the ideal amount of light reaches your eyes whether you are in bright daylight, under cloud cover or indoors.
The pros of Transition lenses
• Transition lenses reduce eye strain and fatigue indoors and squinting in sunlight. They can also lessen glare by regulating the amount of natural light you’re exposed to. The degree to which Transition lenses darken depends on the amount of light.
• Transition lenses darken and turn clear again very quickly; a mere 30 seconds for each action. They maintain about a 5-percent residual tint indoors.
• Because the lenses protect the eye from harmful UV rays, light sensitivity is reduced and, decreasing your eye’s exposure to UV rays also lowers the risk of cataracts and other age-related eye problems.
• Transition lenses can save you money as you won’t need to buy separate prescription sunglasses as well as eyeglasses.
• Vision will be crisper and colors will appear more vivid in sunlight.
• These lenses are ideal for children who may have trouble keeping track of more than one pair of glasses. Eye damage results from a lifetime exposure to UV rays, so protecting children while they are young can help to guard against future problems.
The cons of Transition lenses
The cons are few but worth mentioning:
• Transition lenses won’t work in a care because the windshield blocks the UV rays that initiate the darkening of the lenses.
• They aren’t polarized so, if you are light-sensitive, they won’t reduce hard glare.
• Since the lenses darken as soon as you walk outside, you may have to take them off for outdoor photos. Otherwise, your eyes will be hidden in pictures.
Transition lenses are available in all major lens materials, including polycarbonate and ultra-thin, and can be made as single vision, bi-focals and progressives.