Long-term exposure to ultraviolet radiation can be harmful to the eyes, too. It increases the risk of cataracts as well as of a number of other disorders that impair vision or cause blindness. People who work outdoors, especially near water or in snow, are particularly susceptible to eye damage from UV radiation.

The sun's rays can burn unprotected eyes as easily as they burn the skin. In fact, photokeratitis—temporary blindness—can occur after long exposure to the sun during outdoor activities such as skiing, cycling or water sports. A general rule: If your skin is likely to burn from UV exposure, wear sunglasses as well as sunscreen.

The American Optometric Association recommends sunglasses as the best form of UV protection. Eye doctors suggest sunglasses that block at least 99 percent of UVA and UVB radiation. While some contact lenses also provide UV protection, it's a good idea to also wear sunglasses. Additionally, a good hat with a wide brim reduces ocular UV exposure by 50 percent.

When choosing sunglasses, don't be fooled by expensive options. The key to a good pair of sunglasses is that they provide 99 to 100 percent UVA and UVB protection and are close-fitting and polarized to reduce glare.

Another caution for protecting the eyes is to beware of medications with photosensitizing chemicals such as psoralen compounds for treating psoriasis, oral contraceptives, acne medications and some antibiotics such as tetracycline, doxycycline and sulfa drugs.