The researchers found that pressure-lowering eye drops reduced by more than 50 percent the development of primary open-angle glaucoma, the most common form of glaucoma and one of the nation's leading causes of vision loss. Researchers noted that 4.4 percent of the study participants who received the eye drops developed glaucoma within five years. By comparison, 9.5 percent of the study participants who did not receive the eye drops developed glaucoma. Additionally, personal risk factors, such as older age and African descent, as well as ocular risk factors, such as higher eye pressure, anatomy of the optic nerve, and thinness of the cornea, were associated with the development of glaucoma in study participants.
Elevated eye pressure occurs when fluid that flows in and out of the eye drains too slowly. It is estimated that between 3 million and 6 million people in the United States -- including between 4 and 7 percent of the population older than 40 -- have elevated eye pressure and are at increased risk for developing open-angle glaucoma.
Until now, doctors did not know if treating elevated eye pressure before glaucoma developed could delay the onset of the disease.
"This study shows that physicians can make a real impact in preserving the sight of many Americans with ocular hypertension by using proven therapies already at their disposal for glaucoma care," said James Brandt, professor of ophthalmology and lead investigator of the glaucoma study at UC Davis.
The Ocular Hypertension Treatment Study examined 1,636 people 40 to 80 years of age who had elevated eye pressure but no signs of glaucoma. At UC Davis, 117 individuals were enrolled in the study, the largest enrollment of the 22 centers. Half of study participants were assigned daily eye drops while the other half were observed. In the medication group, treatment reduced eye pressure by approximately 20 percent, which helped to prevent glaucoma.
Despite the benefits of pressure-reducing drops, this drug therapy is not appropriate for all glaucoma-free people with elevated eye pressure. "Doctors should take into account several factors, including the fact that 90 percent of participants in the observation group did not develop glaucoma within the five-year study period," Brandt said. "An individual's risk of developing glaucoma, along with health status and life expectancy, should be considered as well as cost, inconvenience and possible side effects."
Study researchers prescribed commercially available eye drops. "The availability of many different types of pressure-lowering eye drops allows ophthalmologists to choose the safest regimen for each patient," Brandt said.
Open-angle glaucoma affects about 2.2 million Americans age 40 and over; another 2 million may have the disease and don't know it. Glaucoma occurs when the optic nerve is damaged, causing a loss of peripheral, or side, vision. In most cases, increased pressure in the eye plays an important role in this damage. As the disease worsens, the field of vision gradually narrows, resulting in blindness. However, if detected early, glaucoma can usually be controlled. Comprehensive eye examinations are recommended for all people over age 60, and for African Americans, over age 40.
The research study was supported with grants from the National Eye Institute, National Center on Minority Health and Health Disparities, Research to Prevent Blindness and Merck Research Laboratories. More information about the study is available at http://www.
Copies of all news releases from UC Davis Health System are available on the Web at http://news.
Editor: Study results will be announced at a noon EDT news briefing in Washington, D.C., Thursday, June 13, 2002