Eye drops that reduce elevated pressure inside the eye can delay or possibly prevent the onset of glaucoma in African Americans at higher risk for developing the disease, researchers at Emory Eye Center and across the country have found. This makes it more important to identify African Americans at higher risk for developing glaucoma so they can receive prompt evaluation for possible medical treatment. These results are reported in the June 2004 issue of Archives of Ophthalmology.
Scientists found that daily pressure-lowering eye drops reduced the development of primary open-angle glaucoma in African Americans by almost 50 percent. Primary open-angle glaucoma is the most common form of glaucoma and one of the nation's leading causes of vision loss. Of the African American study participants who received the eye drops, 8.4 percent developed glaucoma. By comparison, 16.1 percent of the African American study participants who did not receive the eye drops developed glaucoma. The study was funded by the National Eye Institute (NEI) and the National Center on Minority Health and Health Disparities (NCMHD), two components of the Federal government's National Institutes of Health.
The results of this study, called the Ocular Hypertension Treatment Study (OHTS), are a follow up to initial results released two years ago. In those findings, researchers discovered that treating people with elevated eye pressure could delay or prevent the onset of glaucoma. At that time, results for the subgroup of African Americans trended in the same direction, but were not conclusive.
"The Ocular Hypertension Treatment Study's most recent finding demonstrates the importance of early screening for glaucoma in African Americans. Elevated eye pressure (ocular hypertension) has no symptoms and can only be diagnosed on a screening examination. Numerous eye drops are available to lower the intraocular pressure in those individuals deemed to be at significant risk of developing glaucoma," says Allen Beck, MD, head of the Glaucoma Service at Emory Eye Center. Dr. Beck was a principal investigator in the study.
Primary open-angle glaucoma affects about 2.2 million Americans age 40 and over, half of whom are not aware they have the disease. Vision loss from glaucoma occurs when the optic nerve is damaged. In most cases, elevated eye pressure, also called ocular hypertension, contributes to this damage. This causes gradual loss of peripheral (side) vision. As the disease progresses, the field of vision gradually narrows and blindness can result. Glaucoma has no early symptoms, and by the time people experience problems with their vision, they usually have a significant amount of optic nerve damage. However, if detected early, glaucoma can usually be controlled and serious vision loss prevented. Comprehensive dilated eye examinations are recommended at least once every two years for African Americans over age 40 and all people over age 60.
"This is the first study to recruit large numbers of African Americans to examine the benefit of pressure-lowering eye drops to prevent or delay the onset of glaucoma," said Paul A. Sieving, MD, PhD, director of the NEI. "The results underscore that African Americans over age 40 should receive a comprehensive dilated eye exam at least once every two years to see if they are at higher risk for glaucoma."
Elevated eye pressure results when the fluid that flows in and out of the eye drains too slowly, gradually increasing pressure inside the eye. It is estimated that between three and six million people in the U.S. are at increased risk for developing primary open-angle glaucoma, representing between four and seven percent of the population above age 40. In this study, ocular hypertension was defined as pressure of 24 mm Hg or greater in at least one eye.