Sunglass savvy

Most people, kids included, should own a pair of shades. Ultraviolet rays can increase the risk of cataracts and age-related macular degeneration. The most protective sunglasses are large-framed, close-fitting, and wraparound. Always look for a hangtag or sticker that says "blocks 99 to 100 percent of UVA and UVB rays" or "absorbs up to 400 nm of UV radiation." Our past tests have shown that protection doesn't have to be pricey. Here's lingo to know:

ANSI. The American National Standards Institute, a nonprofit organization, oversees development of voluntary standards for sunglasses and other products.

Tint. It's mainly a matter of preference. For best color perception, Prevent Blindness America, an eye health and safety organization, recommends lenses that are gray, amber, brown, or green. The American Academy of Ophthalmology (AAO) suggests green for most uses, because it offers color contrast with little or no color distortion. (Vermilion, the AAO says, has the worst color distortion.) Darker lenses don't necessarily provide more UV protection.

Polarized. Because they block light waves that align in horizontal patterns when reflecting off flat surfaces, they're useful for fishing, skiing, and driving.

Mirror coating. It's derived from thin layers of various metals coating ordinary lenses and doesn't automatically convey UVA/UVB protection.

Blue blocking. Describes amber-colored lenses that protect eyes from blue visible light. (The AAO notes some evidence that the retina might be more sensitive to that light.)

Impact resistant. The Food and Drug Administration requires all sunglasses to survive an impact test without fracturing but not to be shatterproof.

Polycarbonate. A plastic that resists impact especially well.

Photochromic. These lenses lighten or darken in response to sunlight's intensity. Darkening takes about 30 seconds, according to the AAO; lightening, about 5 minutes.