On most days, Cynthia Popper counts on her contact lenses to do the obvious -- correct her vision. That's unless she's out on the water.
"I do. I do surf with them, they don't come out," said Popper.
The lenses she's wearing offer an increasingly popular feature more commonly associated with sunglasses -- protection from UV rays.
San Francisco optometrist Clifford Lee says the lenses aren't colored like sunglasses and don't change what the eye sees. Instead, polymers in the plastic lenses absorb the UV light waves and prevent them from reaching the cornea.
"Typically it's a soft lens. The soft lens covers the cornea, and therefore it will provide protection to the structures of the cornea and all the structures behind that," said Lee.
UV light has been linked to conditions including the early formation of cataracts.
The new lenses manufactured by several companies come in two classes, with class one offering the best protection, blocking 96 percent of UVA rays and 100 percent of UVB rays.
Still, manufacturers and the California Optometric Association advise patients that the lenses are not a complete substitute for UV rated sunglasses. The reason is that lenses typically don't cover the entire eye, leaving the whites of the eye unprotected and vulnerable.
"Particularly in high exposure activities -- skiing, sailing -- there are some potential growths on the white portion of the eye that can also occur," said Lee.
Lens manufacturers still recommend wearing sunglasses over the contacts when possible.
For Popper, they offer an extra piece of mind in situations where, she says, sunglasses just aren't practical.
"Because you can't see if you're on a board and you're looking out at waves. If you don't have your lenses in, you're not gonna be able to see what's coming at you," said Popper. "So it's nice to know that you have UV protection."
Doctor Lee says different manufacturers offer different degrees of protection. If this is a feature you are interested in, be sure to ask about the specific level of UV protection.
Written and produced by Tim Didion