If you have a favorite pair of sunglasses, you may have been using them for years. How do you know if older sunglasses are still protecting your eyes from ultraviolet (UV) light?
Research doesn't provide a direct answer to the question of whether UV protection deteriorates. The only way to be certain is to get your sunglasses tested.
Sunglasses with the recommended protection will filter out all UV rays. UV rays can damage the eye's surface tissues, cornea and lens. Over time, ultraviolet damage can increase the risk of developing cataracts, macular degeneration and other eye conditions. These conditions can reduce your vision.
A 2016 study from the University of Sao Paolo, Brazil, looked at whether UV protection in sunglasses is adequately tested. "That is not the same thing as testing whether UV protection in sunglasses is wearing off," according to Jeff Pettey, MD, assistant professor of ophthalmology at the Moran Center University of Utah and a spokesman for the American Academy of Ophthalmology.
The researchers found that manufacturers’ tests in Brazil may be underestimating the amount of UV light that hits glasses over time. It’s not clear whether these findings mean anything for U.S. sunglasses testing. Exposure to UV radiation in Brazil is higher than exposure in the United States.
While the study raised more questions than answers, Dr. Pettey says consumers should not be alarmed or rush to replace their beloved set of shades. There is no current recommendation for when people should retire their sunglasses.
UV-blocking technology has improved in recent years. Most sunglasses today have UV protection that is embedded in the lens, rather than coated over it. If you are concerned about the age and safety of your sunglasses, you can have them tested at an optical shop that has a UV light meter.
If you’re ready for a new pair of sunglasses, Dr. Pettey offers these tips for choosing sunglasses with the most protection:
- Look for a label that says "100% protection against both UVA and UVB" or "100% protection against UV 400."
- Choose larger frames that cover the eyes and surrounding skin. Frames that wrap around the sides of the face offer the greatest protection.
- Buy from a reputable retailer. Be wary when purchasing sunglasses from online auction sites, street vendors or flea markets.
These sunglass features do not play any role in UV protection:
- cost;
- lens color or tint;
- lens darkness;
- mirror-coating; and
- polarization.
The most important advice is to "put on your sunglasses whenever you are outside," says Dr. Pettey. The Vision Council reports that only 31 percent of Americans wear sunglasses every time they’re outside. "Sunglasses are to the eyes what sunscreen is to the skin. Whether it’s cloudy or sunny, they are an essential shield to protect your health."