Exposure to UV-B radiation in sunlight has now been shown to increase the risk of cataracts in people who have had fairly low exposure throughout their lifetime, according to an article in a recent issue of The Journal of the American Medical Association (JAMA).

Previously, a link had been shown in studies of people in high-risk occupational groups, but not among a general population.

Sheila K. West, Ph.D., and colleagues, from Johns Hopkins University, Baltimore, studied 2,520 older adults (65 to 84 years old) from Salisbury, Md., from 1993 to 1995 who participated in the Salisbury Eye Evaluation project.

Participants were asked in questionnaires: “For the job you held longest in your life, did you spend more than two hours outside during daylight in the summer months?” and were asked to rate their vision status on a scale of one to 10, with 10 being excellent.

In addition, they were queried about job history since the age of 30, time spent outside during the job and leisure time, geographic location of job and leisure activity, and glasses and hat use while outside.

Then, at an examination center, each participant's eyes were dilated and photos taken of the lenses of their eyes. Photos were graded for the type and severity of opaqueness found on the lens.

The authors write: “Our study is the first to document the relationship between ocular exposure to UV-B and risk of cortical opacity in African Americans.” Slightly more than a quarter of the participants were African Americans. The researchers explain that racial differences do exist in the prevalence of several diseases of the eye.

The odds of developing cataracts increased with increasing exposure to UV-B. The relationship was similar for women and for African Americans. Analysis of the dose of UV-B received by each age group after the age of 30 years showed no vulnerable age group, suggesting damage is based on cumulative exposure.

The authors write: “For this population of older persons in Salisbury, the attributable risk for cortical opacity [opaqueness] due to higher levels of UV-B exposure is 13 percent. These data add to the growing body of knowledge that suggests even low levels of UV-B can harm the lens."

Ways For People to Protect Themselves

The authors write: “Measures to avoid ocular exposure to UV-B in sunlight are simple. The wearing of plastic glasses or sunglasses confers excellent protection, and the simple wearing of a hat with a brim decreases ocular exposure by 30 to 50 percent. These measures should be a part of any public health program to increase awareness of sun damage and avoid unhealthy consequences.” The researchers indicate that despite advances in surgical procedures and targeted programs, cataracts remain the leading cause of visual loss worldwide, and that in the United States, cataract surgery was responsible for 12 percent of the Medicare budget ($3.4 billion annually in 1991). They believe cataracts will become an even more pressing issue for the eye care community in the future.