En español | We reach for sunscreen because we know it's necessary for protecting our skin from the sun's harmful ultraviolet (UV) rays. But when we grab a pair of sunglasses, we may be thinking more about the way they look than about how important they are for protecting our eyes.
"Many patients underestimate how much UV rays can pose a significant risk to their vision,” says Samuel Pierce, an optometrist in private practice in Trussville, Ala., and president of the American Optometric Association (AOA).
In fact, a survey by the American Academy of Ophthalmology found that fewer than half (47 percent) of Americans check the UV ray protection level before buying sunglasses. Here's how to get smarter about shades.
How the sun damages eyes
"UV rays enter the eye and penetrate through the cornea, the clear covering of the front of the eye,” says Pierce. This can be harmful in several ways.
In the short term, overexposure to the sun can cause irritating effects like bloodshot eyes, swollen eyes or hypersensitivity to light. Photokeratitis, or “sunburn of the eye,” can also happen, Pierce says. Symptoms include red eyes, a gritty feeling in the eyes, extreme sensitivity to light and excessive tearing. These effects are usually temporary.
In the longer term, unfiltered light can damage not only the cornea but also the lens of the eye, the skin of the eyelid and the retina. This can lead to growths on the eye, early cataract formation and macular degeneration, says Ming Wang, M.D., founding director of Wang Vision 3D Cataract and LASIK Center in Nashville. “It can also lead to certain types of skin cancers that are difficult to treat due to their location near the delicate structures of the eyelids,” he says. The Skin Cancer Foundation reports that 10 percent of all skin cancers are found on the eyelid.
Additional risk factors
The simple fact of aging can increase your chances of developing cataracts and macular degeneration as a result of UV exposure. But once people have had cataract surgery — which is often performed between ages 50 and 70 — the risk increases even more.
"While most intraocular lens models implanted during cataract surgery do offer UV protection, it may not be as comprehensive as that provided by the eye's natural lens,” Wang says. That's why it's particularly important for people to wear sunglasses after having this surgery, he adds.
Certain medications also can increase the risk of photophobia, or light sensitivity, which can cause discomfort, the need to squint or close the eyes and headaches. Some of these drugs include belladonna, furosemide, quinine, tetracycline and doxycycline, Pierce says. “Even some over-the-counter pain relievers — notably ibuprofen and naproxen — have been shown to bring about painful light sensitivity as a side effect,” he notes. Sunglasses can help in these cases as well.
How to protect your sight
The use of sunglasses may help to reduce the likelihood of damage, Wang says. But it depends on the pair you pick and how you wear them.
Eye-protection tips from the experts:
• Be a stickler for UV blocking. “When shopping for sunglasses, it's important to verify that they block out 99 to 100 percent of UVA and UVB rays and screen out 75 to 90 percent of visible light,” Pierce says. The label may indicate “100 percent protection against UVA and UVB” or “100 percent protection against UV 400,” which means that the glasses block rays as small as 400 nanometers.
• Consider the shape. “The best sunglasses are those that wrap around the face, as this blocks light from all sources and provides the most protection compared to flat-fronted sunglasses,” Wang says.
• Don't let the tint color fool you. The tint of the lenses doesn't determine the protection, Wang says. “Lighter-tinted glasses can still provide strong protection."
• Opt for “polarized." This type of lens reduces reflections off horizontal surfaces, such as water, snow and the hood of a car. “While polarization is not necessary to provide additional protection, it does reduce this source of eye strain,” Wang notes.
• Realize they're not just for sunny summer days. Experts suggest wearing sunglasses even on cloudy days.
Pierce says the sun's rays can actually be more harmful during the winter — especially at high altitudes and on reflective surfaces such as snow and ice.
Second, clouds don't offer full protection from the sun. “In partial sun or clouds, UV light still penetrates through and it's still a good idea to wear sunglasses,” Wang says.
• Go for quality, not necessarily brand name. Many people are willing to pay hundreds of dollars for a pair of designer sunglasses. Is that smart? “Often you are paying for the label and the look,” Wang says. “However, they are generally using higher-quality lenses as well.”
Lower-cost sunglasses often meet the minimum requirements, too, he says. “But you need to use more caution to ensure that the lenses do in fact meet the standards.” You can take any pair of sunglasses to an optometrist, who can test the lenses to be sure they provide the proper UV protection.
• Wear them over contacts. Some contact lenses offer UV protection, but they should still be worn with sunglasses to maximize eye protection, according to the AOA.
• Don't forget kids. “Wearing sunglasses early in life is particularly important because children often spend much more time outdoors than adults,” Wang says. “Sunglasses can have protective effects against damage occurring much later in life.”
• Go beyond sunglasses. “Applying sunscreen around the eyes and wearing a hat or visor in addition to sunglasses can help improve protection,” says Pierce.
• Avoid looking directly at the sun. You've heard this advice during eclipses, but it's true all the time. “If someone looks directly at the sun at any time without protection,” Wang says, “it can cause temporary or permanent damage to the retina.”