Some manufacturers of sunglasses are as shady as the products they offer. Labeling can be ambiguous concerning the level of UV protection, and even seemingly straightforward proclamations, such as "100 percent protection," can be outright false, according a new study.
No trivial concern, the sun's invisible ultraviolet radiation can sunburn your eyes just as it burns your skin, causing immediate damage and long-term vision problems, such as cataracts and retinal and macular degeneration.
Yet the sunglass industry is loosely regulated. Should manufacturers get caught lying about their labeling, their punishment if any would be a tersely worded letter from the FDA warning them to change their ways.
Consumers have little guarantee that what the protection they think they are buying is real. The best you can do is to stick to brands from trustworthy manufacturers, such as those specializing in outdoor gear, and take the sunglasses to an eye doctor for real testing.
Blinded by the falsehood
Australia is the only country with a law defining suitable sunglass standards. Sun protection is a serious issue on this island continent, where UV intensity is at least 15-percent greater than at similar latitudes in the Northern Hemisphere. That's due to clearer skies and the Earth's closer proximity to the sun during the summer season from December to March. Skin cancer rates are among the highest in the world for this largely white population plopped into these sunny climes as recent as a few hundred years ago.
As relayed in the May 2010 issue of the journal Ophthalmic and Physiological Optics, researchers from the University of New South Wales in Sydney found that over 20 percent of the sunglasses made in Europe were falsely labeled, not meeting stated levels of protection for UV, polarization or other requirements for the Australian market.
Unfortunately, similar studies testing sunglasses made or sold in the United States have tended to be small or non-scientific, such as those conducted by intrepid television news reporters. Yet most of these studies have shown that labeling is often false and that mislabeling occurs regardless of the price of the sunglasses, from cheap $15 shades to $400 designer sunglasses.
What to look (out) for
Setting aside the mislabeling issue for the moment, for complete protection, look for sunglasses offering 99- to 100-percent UV protection. This level implies 99-percent and 95-percent protection from two types of UV, respectively — the shorter-wavelength and more damaging UVB and longer-wavelength yet still menacing UVA — as determined by the American National Standards Institute, a nongovernmental body.
Terms such as "UV absorbing" or "blocks most UV light" mean nothing; these are just wiggle words to get around the loose FDA regulations. The term "UV 400" implies protection against UVB and UVA, filtering light up to the UVA threshold wavelength of 400 nanometers. But you still need something stating 99- to 100-percent protection in this full range. So-called 100-percent protection might only apply to a narrow slice of the UV spectrum.
For full protection, wrap-around shades are best. Your 100-percent protection must be averaged with zero-percent protection if unfiltered light enters in from the sides.
Polarized lenses reduce glare but offer no additional UV protection. Similarly, lens darkness means little; darkness is related only to the extent you want to look like a blind blues musician. You can buy eyeglasses with but a slight tint offering 100-percent UV protection.
"Blue-blockers" are glasses that go a step further to filter blue-wavelength visible light, just below ultraviolet radiation on the electromagnetic spectrum. This might be overkill, but the protection isn't utterly unwarranted. Scientists remain uncertain whether this near-ultraviolet light is harmful. Those of us with the greatest sun exposure — skiers and boaters (exposed to glare bouncing off of snow and water) and pilots — might want this extra level of protection.
Should you be geeky enough to possess a UV laser, you can shine it through your sunglasses to estimate the level of protection. An eye doctor should have the equipment to test precisely how much of what wavelength is getting through.
I myself was surprised to find my $15 sunglasses, a big buy for me, offered less than 50-percent protection. Half protection is worse than no protection, however. The darkness of my lenses was causing my eyes to dilate and allow even more UV light to penetrate to the back of my eyeballs. Now I've seen the light.
- You and the Sun: 10 Burning Questions
- 7 Solid Health Tips That No Longer Apply
- Video - Smart Sunglasses
Sign up for the Live Science daily newsletter now
Get the world’s most fascinating discoveries delivered straight to your inbox.
Christopher Wanjek is a Live Science contributor and a health and science writer. He is the author of three science books: Spacefarers (2020), Food at Work (2005) and Bad Medicine (2003). His "Food at Work" book and project, concerning workers' health, safety and productivity, was commissioned by the U.N.'s International Labor Organization. For Live Science, Christopher covers public health, nutrition and biology, and he has written extensively for The Washington Post and Sky & Telescope among others, as well as for the NASA Goddard Space Flight Center, where he was a senior writer. Christopher holds a Master of Health degree from Harvard School of Public Health and a degree in journalism from Temple University.