You may have seen news articles suggesting that the effectiveness of sunglasses offering UV protection deteriorates over time. As the thinking goes, the UV coating embedded in eyewear lenses doesn’t last forever. It breaks down as a result of exposure to those same ultraviolet rays that are so dangerous to human eyes.
If the concerns prove to be correct after stringent scientific study, the next task would be to determine how frequently a pair of sunglasses should be replaced. But such considerations are a long way off. The fact is that right now, no one really knows. Any dogmatic statements about the effectiveness of UV protection over time are nothing more than speculation.
Testing Sunglasses in Brazil
The sudden concern over the effectiveness of sunglasses with UV protection originates from Brazil. Apparently, a group of Brazilian researchers looking into ocular diseases questioned the validity of UV protection over time. Their concerns were numerous, including the fact that much of Brazil is on or close to the equator and the average Brazilian citizen wears his/her sunglasses for a minimum of two hours per day, every day.
Researchers decided they wanted to test how effective older sunglasses are in protecting against UV rays. According to University of São Paulo researcher Dr. Liliane Ventura, “there are no means to guarantee that UV protection does not change over time,” in the absence of a new kind of aging test.
Ventura’s issue is that the means used to test sunglasses in Brazil is inadequate for determining the long-term effects of UV rays on lenses. In her view, the risk is serious enough to warrant further research. That’s what her team is doing. They have devised new testing methods that more closely reflect real-world sun exposure in Brazil.
There Is No Proof
Dr. Ventura also stated that “it’s still too soon to confirm that UV protection deteriorates with sun exposure.” That statement, combined with others she has made, makes it clear that the Brazilian team hasn’t reached a conclusion one way or the other. Unfortunately, the media tends to only focus on the possibility that UV protection might deteriorate.
UV protection is embedded in a pair of sunglasses via a special film that cannot be seen, according to Olympic Eyewear. Olympic representatives say that lens color has nothing to do with it. The film in question is independent of any specific tint. Why is that important? Because a fading tint doesn’t necessarily equate to less effective UV protection.
The fact remains that there is no proof that UV protection degrades with time and exposure. The possibility that such degradation might occur is not enough to warrant suggesting people replace their sunglasses every year or two. Most of us buy a new pair of sunglasses every year anyway, so it seems fruitless to give a whole lot of attention to the question of degradation until science has done more work.
Purchase Choices Are Still Important
While researchers are trying to figure out the degradation question, it’s still important to remember that protecting the eyes against UV rays is a good idea. And in that respect, purchase choices are as important today as they were at any time in the past.
Sunglasses offering UV 400 protection protect the eyes against all ultraviolet rays. Anything less gives only partial protection. As a general rule of thumb, sunglasses should be rated at least UV 300. Anything less and you’re not getting the protection your eyes need.
Does UV protection degrade over time? No one knows right now. So don’t jump on the bandwagon just yet.