Black Americans suffer from glaucoma, an eye disease that causes blindness, at four to five times the rate of white Americans, according to a study by researchers at the Johns Hopkins Dana Center for Preventive Ophthalmology.
The study, which will be reported in today's Journal of the American Medical Association, shows that one in eight blacks have glaucoma by age 70, compared to only one in 50 whites.
The high rate of the disease among blacks appears unrelated to social or economic status or to the use of eye-care services.
Thus, the study suggests that "blacks have an inherent predisposition to developing glaucoma," said Dr. Alfred Sommer, dean of The Johns Hopkins School of Hygiene and Public Health and one of the study's head researchers.
He urged all blacks over 40 to have eye examinations every one to three years to check for glaucoma, which can be controlled if it is diagnosed and treated early.
The Baltimore Eye Survey, which examined 2,395 blacks and 2,913 whites, is the first study to measure
glaucoma prevalence in a large, racially mixed population.
The participants, all 40 or older, lived in East Baltimore in poor to middle-class neighborhoods.
In the United States, an estimated 3 million people have glaucoma.
Another 10 million are at a greater-than-average risk of developing it.
The disease occurs when the fluid pressure inside the eye increases and damages the optic nerve, causing vision loss that can lead to blindness.
Doctors have suspected that blacks are at greater risk for glaucoma since researchers for the National Eye Institute examined state blindness registries in the 1970s.
They discovered that blindness in non-whites is more commonly caused by glaucoma than by retinal degeneration, which causes more blindness in whites.