Block Those Bad-Guy UV Rays
Eye docs' number one rule: Shades should shield you from harmful ultraviolet rays. And if you're light-eyed, you may be more sensitive to damage. "Whether your sunglasses cost $25 or $500, don't fall for phrases like 'absorbs most UV light,' " says Dennis Fong, O.D., a clinical faculty member of the University of California, Berkeley, School of Optometry. The only trustworthy promise: "Blocks 99% to 100% of UVA and UVB rays."
Get a View with Minimal Glare
Friends don't let friends squint and drive. To stay safe on the road—whether you're behind the wheel of a car or riding a bike—look for polarized lenses. These nix glare and keep vision clear, says ophthalmologist and clinical researcher Robert Abel, M.D. Just be sure your polarized lenses also offer full UV protection.
Go Big, Not Skimpy
The more coverage the frames offer, the better. A serious pair of Jackie O's—that means large frames, big lenses, and wide arms—is ideal. They'll shield more of your eyes, and the highly delicate skin around them, from sun damage.
Beware of Cheapies
Who hasn't been tempted to grab a fun pair from a street vendor? But cute doesn't cut it if the lenses distort your view so that driving or, say, biking isn't safe. Do this DIY test: Close one eye and look through the glasses at a straight edge, like a door frame. If the lines of the door appear wavy or it seems as if you're gazing through a glass bottle, spend a little more.
Don't Believe the Dark Tint Myth
Sunglasses' ability to stop UV light is not related to how dark they are. "If they don't have enough UV protection, dark lenses can do more harm than good," says Andrea P. Thau, O.D., vice president of the American Optometric Association. It's like being in a dim room: Your pupils dilate to let in light, so dark lenses allow more radiation in than if you weren't wearing them at all. Provided they have the right UV blockage, dark shades in neutral tones are great for bright, beachlike conditions, while lighter lenses are fine for strolling around shadier streets. Grays lower light intensity without messing with color—ideal for driving. Not so for amber or yellow lenses, which can alter color perception.
Lenses with antiscratch coating keep your view crystal clear. Warby Parker Reilly Sunglasses ($95, warbyparker.com)
Pretend the paparazzi are out there, and always stay behind your shades. "People tend to think more about the sun in summer, but UV rays can get through clouds in any season," says Thau. "I wear sunglasses year-round, even on overcast days."
6 Safe, Stylin' Pairs
This story originally appeared in the July/August 2015 issue of Dr. Oz The Good Life.