Sunglasses and UV: choosing a pair that protects

Most people think about sunscreen for their skin. Fewer think about their eyes, even though ultraviolet (UV) light affects them too. Sunglasses are a simple way to reduce UV reaching your eyes, but not every pair offers the same protection, and the things that make a pair look protective aren't always the things that matter.

Why UV matters for your eyes

According to the World Health Organization and the American Academy of Ophthalmology:

• Short-term effects. UV can cause photokeratitis, a kind of sunburn on the front of the eye. The AAO says it can cause redness, blurry vision and sensitivity to bright light. The WHO notes these effects are reversible and easily prevented by protective eyewear.
• Long-term effects. The AAO says long-term sun exposure without protection can increase the risk of eye disease, including cataract, growths on the eye and eye cancer.
• Cataract. The WHO estimates that about 15 million people are blind due to cataracts, and that some 10 percent of these may be due to UV exposure.

What to look for

• Full UV protection. The WHO recommends sunglasses that block 99 to 100 percent of UVA and UVB. Labels vary: some say "100% UV protection", others "UV400". The AAO says either kind blocks essentially all harmful rays.
• Wraparound or larger frames. Both the WHO and AAO recommend wraparound styles, which limit UV coming in from the sides.
• A hat as well. The WHO suggests a broad-brimmed hat to protect the eyes, face, ears and neck.

Common myths

• "Darker lenses protect more." The AAO says lens tint doesn't indicate UV protection. Darker lenses don't block more UV.
• "Polarised lenses protect more." Polarised lenses cut glare from water and pavement, which can make them more comfortable. The AAO says they don't add sun protection on their own.
• "Expensive means better." The AAO says cheaper pairs labelled 100 percent UV-blocking can be just as effective as pricier ones.
• "I only need them on sunny days." The AAO notes that harmful UV rays are present even on cloudy days.

When UV is stronger

The WHO recommends sun protection when the UV index is 3 or above, and advises limiting time in the midday sun and seeking shade. The higher the UV index, the greater the potential for damage to the skin and eyes. Many weather apps show the daily UV index.

The AAO also notes that photokeratitis often comes from light reflecting off water. Sand and snow can reflect UV too, so take extra care at the beach, on the water and in the mountains.

Children's eyes

The AAO says children are just as susceptible to the sun's harmful rays as adults, and that it helps to start good habits early. Look for children's sunglasses that are labelled with full UV protection, fit well and are comfortable enough that they'll keep them on. A hat with a brim is a good addition.

Other tips

• Never look directly at the sun, including during an eclipse, even with ordinary sunglasses.
• If you wear prescription glasses, ask your optometrist about prescription sunglasses or other options with UV protection.
• Keep a spare pair in the car or your bag so you have them when you need them.

When to see someone

Book an appointment with an optometrist or eye doctor if:

• Your eyes often feel uncomfortable or sensitive in bright light
• You notice a growth or change on the white of your eye or your eyelid
• Your vision seems to be getting cloudier or more glary over time