March 14, 2000 (Los Angeles) -- Dermatologists know that too much sunshine can give you wrinkles and skin cancer. Here's another reason to stay out of the sun: a growing body of evidence links it with the development of cataracts.
Cataracts, a clouding of the eye's lens, are the leading cause of blindness in the world and account for 50% of the vision loss seen globally, write the authors of a new study in the medical journal Archives of Ophthalmology. In the U.S., cataract surgery is the most common surgical procedure in people aged 65 or more, at an estimated annual cost of $3.4 billion.
According to New York cataract surgeon Charles Kelman, MD, who was not involved in the study, in India alone, "there are more than 20 million blind people from cataracts, and not enough ophthalmologists to take all the cataracts out."
To conduct their study, author Cécile Delcourt, PhD, and her colleagues at the Institut National de la Santé et de la Recherche Médicale (INSERM) in Montpellier, France, studied the development of cataracts in more than 2,500 residents of Sète, a village in south France. From measurements of the sunlight that reached the ground, plus detailed interviews and medical histories of the participants, they were able to estimate the amount of sunlight to which each subject had been exposed over a lifetime.
The researchers found an association between high exposure to solar radiation and a 2.5 to 4 times greater risk of cataracts, depending on the type of cataract studied -- as well as a 2.9 times greater need for cataract surgery. The risk was not related to age, but instead to an individual's accumulation of light exposure over a lifetime, starting in childhood. Regular wearers of sunglasses decreased their cataract risk by as much as 40%.
"If you live long enough, you will get cataracts," Says Kevin Miller, MD, an associate professor of clinical ophthalmology at UCLA School of Medicine. However, certain environments can hasten their development.
According to Kelman, "It has long been known and accepted that ultraviolet light [such as that found in sunlight] can ... increase the risk of cataracts." In general, "the closer you get to the equator, the greater your risk."
Both clinicians recommend wearing sunglasses as long as they filter out ultraviolet light, but Kelman warns that "if a patient wears dark glasses that don't filter out ultraviolet rays, it could actually increase their risk "because the dark lenses may actually permit more ultraviolet light to penetrate the eye. He and Miller suggest that supplements of the antioxidant vitamins A, C, and E may prevent the formation of cataracts, although no data have confirmed this yet.
Miller also recommends that patients stop smoking, since that has been linked with accelerated cataract formation. Some drugs have also been associated with an increased risk of cataracts, such as corticosteroids, taken by many people with asthma or rheumatoid arthritis, and phenothiazines, anti-psychotic agents prescribed to people with schizophrenia. He acknowledges, however, that the benefits of these agents could outweigh whatever role they play in cataract formation.
- Cataracts are the leading cause of blindness and account for 50% of vision loss around the world.
- A new study shows that exposure to the sun, accumulated over a lifetime, increases a person's risk of cataracts.
- To lower your risk of cataracts, consumers can wear sunglasses that block UV radiation, and some experts believe taking antioxidant vitamins is also beneficial.