Q: Recently, my pediatrician surprised me by suggesting that my children wear sunglasses when they are outside. We know about sunscreen but if they don't look directly at the sun, what is the need for sunglasses?
A: Your pediatrician is quite right to insist on sunglasses. Just as ultraviolet rays can damage the skin over time, so, too, can these same rays injure a child's eyes.
As your question suggests, most everyone knows that directly looking at the sun allows high energy wavelengths of visible light to pass directly to the retina and damage it. However, infants and children under age 10 have less light-absorbing materials (called chromophores) in the lens of the eye so larger amounts of light can pass to the retina even without directly looking at the sun.
If the chromophores are forced to absorb a considerable amount of light over time (from childhood on), they undergo changes that can lead to cataract formation. You may have read recently of a study that showed that Maryland watermen are at increased risk of cataract formation because of this continuous light exposure.
Dr. Rudolf Wagner, co-director of pediatric ophthalmology at Children's Hospital of New Jersey, suggests several guidelines for choosing sunglasses. The darkness of the lens is not a good indicator of protection. For adequate eye protection, the glasses must absorb 99 percent of UV radiation. The label on the sunglasses should read "blocks 99 percent of UV rays," "UV absorption up to 400 nm," "meets ANSI standards" or "special purpose."
Similarly, mirrored or polarized lenses are not adequate unless they carry the above labels. Be sure to choose nonbreakable plastic lenses.
Finally, remember that sunglasses will only protect the eyes. If you children spend a lot of time outdoors (10 a.m. to 2 p.m. is when sun light is most intense), be sure to apply sunscreen often. Use of a hat (such as a baseball cap) will shield the face and the eyes.
Dr. Wilson is director of general pediatrics at Johns Hopkins Children's Center; Dr. Joffe is director of adolescent medicine.