Several shelves full of sunglasses

When you think of the damage the sun can do, your first thought may be of the ultraviolet (UV) radiation that can burn your skin, increasing your risk of skin cancer. But the sun can harm your eyes as well.

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“I think people are aware of skin damage from UV simply because sunburn hurts,” says Joan E. Roberts, Ph.D., a professor of chemistry at Fordham University in New York. But sun damage to the eyes can accumulate slowly over time, without you noticing, until irreversible harm has been done, Roberts says.

Just as sunscreen shields your skin by blocking UV radiation, sunglasses can shield your eyes from harmful rays. But not every pair is equally good at doing so. Here, what you need to know about how the sun can injure your sight, and how sunglasses safeguard your eye health.

The Sun’s Radiation and Your Eyes

Exposure to sunlight can increase the risk of several vision-impairing conditions. One of the most common is cataracts, which occur when the lens that refracts light into your retina becomes clouded, interfering with proper vision.

According to Adam Gordon, O.D., M.P.H., a clinical associate professor at the University of Alabama at Birmingham’s School of Optometry, a number of studies over the last few decades have found a link between exposure to UV radiation from sunlight and the risk of cataracts. For instance, a 2014 study conducted in France found that people who lived in places with more sunlight were more likely to need surgery to remove a cataract.

Other research has found a link between sun exposure and macular degeneration, which occurs when the macula, a part of the retina, becomes damaged, causing distortions in what you see, blurriness, or difficulty seeing fine details. It’s the leading cause of blindness in older adults, according to Douglas Lazzaro, M.D., a professor in the department of ophthalmology at NYU Langone Health.

Lazzaro also says the sun can damage the skin around the eye, where few of us are diligent about applying sunscreen. That raises the risk of skin cancer of the eyelid. In fact, as many as 20 percent of all cases of basal cell carcinoma, the most common type of cancer, occur on the eyelids, according to a recent analysis.

The experts we consulted, as well as the Centers for Disease Control and Prevention and the World Health Organization, recommend using sunglasses as a way to reduce your eyes’ exposure to harmful UV radiation. But you have to buy the right kind, because not all sunglasses will fully block the sun’s UV rays.

How to Pick Sunglasses for Eye Health

Look for the most protection. When shopping for sunglasses, choose a pair with a label that says the product blocks 100 percent of UVA and UVB rays, the two most concerning types for eyes. (You can also look for the term “UV 400,” which means the same thing, Lazzaro says.)

Go big. Even while wearing sunglasses, some of the sun’s rays can still reach your eyes and the skin around them. Choosing larger lenses can help maximize sunglasses’ ability to stop rays from reaching your eyes and skin. Wraparound sunglasses, which conform to the curve of your face, are even better. Add a hat, which can provide extra eye protection.

Know that pricier isn’t always better. The most effective sunglasses aren’t necessarily more expensive. “You can get very inexpensive sunglasses that have 100 percent ultraviolet blocking ability,” Gordon notes.

Don’t worry about lens color. In addition to UV-protection claims, you’ll likely see various lens colors and levels of tinting, along with some that are mirrored or polarized. None of these features affect how much UV light the sunglasses will block, although polarized lenses can help cut down on glare, which can be irritating, especially if you’re around water.

Get shades for the kids, too. Although the consequences of sun damage to the eyes might not be evident until later in life, it can start to accumulate from a young age, so kids should wear sunglasses, too. Opt for lenses with a label that says they’re made from polycarbonate rather than glass, which is impact resistant and less likely to shatter if they’re hit during a volleyball game or other activity.