Style is the typical driving factor when shopping for shades, but equally important is the UV protection the lenses provide, the reason sunglasses were developed in the first place.

UV protection gets priority during summer months when longer days and vacation time add up to more hours spent outdoors, but wearing the right sunglasses, like wearing the right sunscreen, should be of concern all year round.

The sun can damage many parts of the eye, and sunglasses offer the best protection, said Dr. Steve Rhee, an ophthalmologist specializing in cornea and external disease at Hawaiian Eye Center.

Just as the skin can burn, the surface of the eye can also experience sunburn. "Certain cancers can develop on the eyelids, eye surface and the inside of the eye after prolonged sun exposure," Rhee said. Without adequate sun protection, pterygium (thickening of the outer surface of the cornea that might impede vision), cataracts and macular degeneration can also develop over time.

There are three types of ultraviolet radiation emitted from the sun: UVA, UVB and UVC. UVA and UVB can cause the most damage, while UVC is absorbed by the ozone layer in the atmosphere and does not reach the eyes, Rhee said.

"When buying sunglasses I would check the label for the 100 percent UVA and UVB protection. That is the most important feature to look for when shopping for sunglasses," he said. "I would also recommend getting wraparound-style sunglasses, which prevent light from leaking around the sides."

DON’T BE FOOLED by the color of lenses. Darker lenses are generally perceived as offering more protection but are not necessarily better, Rhee said. "As long as the lens provide 100 percent UV protection, the level of darkness sushouldn’t matter. However, using dark glasses that offer little UV protection may be worse than not wearing them at all since the pupils will dilate more, letting in more UV light."

If you have sensitive eyes or enjoy water sports or skiing, polarized lenses reduce glare, providing comfort for the wearer, but do not provide added protection if not made out of UV-blocking materials, like polycarbonate, or without a UV-blocking dye or coating.

Sunglass Hut at Pearlridge Center offers an array of styles, and all of the sunglasses in the store have 100 percent UVA and UVB protection, which leaves out the guesswork.

The drugstores normally label their glasses with stickers. Longs at Pearlridge Center had a pair of wraparound glasses with full protection for $16.99. But if a tag reads "100 percent UV protection" but doesn’t indicate UVA or UVB, Rhee warns to be cautious. The lens might screen for one but not the other.

Discount stores also carry sunglasses with full protection, like the Panama Jack shades available at Walmart for $15.

In general, Rhee suggests avoiding outdoor activities from 10 a.m. to 3 p.m. when the sunlight and solar radiation are at their most intense. And don’t let down your guard on cloudy days. UV rays pass through clouds, so sunglasses are still necessary.

"Wearing a wide-brimmed hat adds another layer of protection," Rhee added, while recommending buying form-fitted glasses with straps for children to protect the most vulnerable eyes. "Kids need sun protection, so don’t forget about them."