Patti S. is a member of VSP's Ophthalmic Services division.

Real sunglasses are more than just darkly tinted lenses in a cool frame. Although these types of glasses may serve a function in terms of fashion and diminished light transmission, they are not sufficient, in my opinion, to act as genuine protective sunwear.

Truly protective sunwear should, at a minimum, include a tint with ultra-violet [UV] protection. Many materials, (e.g., polycarbonate), naturally absorb harmful UV rays and don’t require an additional coating. Tinted lenses, however, don’t reduce the disturbing affects of glare—they just reduce light transmission.

Polarized lenses do decrease glare and are an indispensable feature I want when buying my own sunglasses. Glare is created when light bounces off a surface. The more reflective a surface, the more glare is produced. A wet road produces more distracting and interfering glare than a dry one, but both surfaces do reflect light. Glare actually interferes with your vision and can obscure images, like children playing in the street or the rear bumper of the car you’re following.

Polarized lenses can be likened to microscopic venetian blinds for your eyes. They actually contain a filter that’s embedded with iodine crystals stretched so that they are oriented in one direction. When rotated correctly prior to insertion into your frame, they reduce visual interference from glare created from light bouncing off horizontal surfaces by preventing those scattered rays from reaching your eyes. Fishermen love them because they allow them to see into the water, not merely the bright reflection off the water.

There are many lens options you can add to polarized lenses, including anti-reflective coatings, variable tints, and a variety of colors. They are also available in almost any multi-focal or single vision design. Polarized lenses are more expensive than simple tinted lenses, but they serve a vital function in terms of your health and comfort as well as your own and others’ safety.