Dr. V. Vinod Mootha, a specialist in cornea, external disease, refractive and cataract surgery, said sunglasses should be used by adults and children when outdoors for prolonged periods of time.
"Excessive exposure may increase the risk for the formation of a fleshy tissue over the cornea, some forms of cataract, and possibly macular degeneration," Mootha said in a statement. "For eyeglass wearers, polycarbonate lenses, which are thin and shatterproof, offer protection from ultraviolet radiation."
Ultraviolet B -- shortwave -- exposure is higher on sunny days, especially at noon, and low-ozone days. UVB, the chief cause of skin reddening and sunburn, tends to damage the skin's more superficial epidermal layers.
It plays a key role in the development of skin cancer and a contributory role in tanning and photoaging. Its intensity varies by season, location, and time of day -- during the U.S. summer the most significant amount of UVB hits the between 10 a.m. and 4 p.m.
Mootha says some sunlight is good for people, but common sense should be a guide for limiting exposure time while minimizing the chance of damage to eyes.