Did you know that sunglasses, or at least sunglass lenses, regularly need to be replaced?
According to a study conducted at the University of São Paulo, the UV protection that sunglasses provide deteriorates over time. You may adore your current ones, but if you’ve been rocking those shades for two or more years, it might be time to get a new pair.
In addition to the UV-blocking properties, anti-reflective and anti-scratch coatings wear down, and the frame material may become brittle over the years, too. Even if you have the most durable sunglasses available, regular lens-replacement is the best way to ensure that your vision is maximally protected from the harmful effects of ultraviolet light.
UV Light and Sunglasses
The protective efficacy of your sunglasses comes in large part from the lens coating of dyes and pigments that reflect and absorb ultraviolet radiation. They create a barrier that prevents UV radiation from penetrating your eyes.
However, this protective coating can, and often does, break down over time. Wear and tear can cause an invisible web of tiny abrasions, compromising its UV-blocking power. Furthermore, the protective dyes and pigments aren't able to absorb UV rays indefinitely; the more sunlight they’re exposed to, the more rapidly they’ll become ineffective.
A pair of shades worn on occasion and in mild conditions is likely to remain effective longer than a pair that is heavily used in a more intensely sunny environment. For example, if you spend long days on the water paddling, kayaking, or canoeing, the protective coating on your lenses will deteriorate more quickly than it would if you only wear your shades to go grocery shopping or sit in a cafe.
Why It's Important to Protect Your Eyes From UV
Protecting your eyes from the sun is critical no matter where in the world you are, as UV exposure places you at risk for developing eye diseases like eye cancer, pterygium, and pinguecula — which can result in disfigurement and discomfort — as well as cataracts and macular degeneration — which cause vision loss and, in severe cases, blindness.
Even short-term overexposure can result in photokeratitis, a corneal sunburn. Symptoms include eye pain, swelling, light sensitivity, and temporary vision loss. Some people experience it when spending too much time boating or skiing without wearing eye protection. Snow and water can increase solar exposure because they reflect sunlight toward your face.
What to Look for When Getting New Sunglasses
When choosing new sunglasses, make sure they’re labeled 100% UV protection or UV400. Although most pairs sold in the United States and Canada offer this degree of protection, it’s still worth confirming before making the purchase. Keep in mind that factors like cost, polarization, lens color, or darkness don’t have much to do with the level of UV protection. Even clear prescription lenses can be UV protective.
It's important to note that there is a lot of counterfeit sunwear in the marketplace. This is dangerous since counterfeit eyewear may not provide much-needed ultraviolet protection. So if the price of a renowned brand is too good to be true, it's probably a fake.
The size and fit of the sunglasses is important. Bigger is definitely better if you spend a lot of time outdoors. Larger wrap-around eyewear is best if you regularly ski or spend many hours in the water, as this style blocks light from all directions.
To find out whether it's still safe to wear your favorite shades, visit a San Francisco eye doctor to determine whether your lenses still offer the right level of UV protection. It’s also a good opportunity to discuss prescription sunwear.
For more information about UV safety, or to get the perfect sunglasses tailored to your vision needs and lifestyle, contact Drs. Hiura & Hiura in San Francisco today!