June 13, 2002

Study shows that eye drops delay the onset of glaucoma for high risk individuals

Ann Arbor—Elevated eye pressure is a risk factor, but not an absolute predictor, for glaucoma, a disease that affects some 2.2 million Americans. A new study shows that eye drops used to treat elevated pressure inside the eye can be effective in delaying the onset of glaucoma. The findings appear in the June 2002 issue of Archives of Ophthalmology.

Scientists 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 those who did not receive the eye drops developed glaucoma. In addition, several significant risk factors were found to be associated with the development of glaucoma in study participants. These included personal risk factors, such as older age and African descent, as well as ocular risk factors, such as higher eye pressure, certain characteristics in the anatomy of the optic nerve, and thinness of the cornea.

The University of Michigan Kellogg Eye Center was one of 22 eye centers participating in the study, which was sponsored by the National Eye Institute and the National Center on Minority Health and Health Disparities.

Terry J. Bergstrom, M.D., Principal Investigator of the study for Kellogg, says that doctors have long faced the question of whether they could prevent or delay the onset of glaucoma by treating patients with elevated eye pressure. "While the study shows that some can benefit from early treatment, we still have to weigh many factors before deciding upon treatment," he said. "It’s important to note that 90 percent of the participants did not develop glaucoma during the five-year study. If a patient does not show other risk factors for glaucoma, it would be reasonable to follow that patient without treatment."

Dr. Bergstrom explains that physicians do not always prescribe medication for elevated eye pressure. "We have to consider that for some patients daily treatment has disadvantages, such as cost, inconvenience, and possible side effects," he says.

People at greatest risk for glaucoma include African Americans over age 40, everyone over age 60, and anyone with a family history of the disease. Elevated eye pressure is also a risk factor. Dr. Bergstrom recommends that people with any of these factors see an ophthalmologist for a dilated eye examination.

Elevated eye pressure results when the fluid that flows in and out of the eye drains too slowly and gradually increases the pressure inside the eye. It is estimated that between three and six million people in the U.S. have elevated eye pressure and are at increased risk for developing open-angle glaucoma.

Glaucoma occurs when the optic nerve is damaged, leading to a loss of peripheral (side) vision. In many cases increased pressure in the eye plays an important role in the damage. As the disease worsens, the field of vision gradually narrows and blindness can result. If detected early enough, through a comprehensive eye exam, glaucoma can usually be controlled and serious vision loss prevented.

One of the distressing aspects of glaucoma is that a person who has open angle glaucoma may not have symptoms until considerable damage to vision has occurred. As many as two million people have the disease and don’t know it.

The study, called the Ocular Hypertension Treatment study, examined 1636 people from 40 to 80 years of age who had elevated eye pressure but no signs of glaucoma. Half were assigned daily eye drops, and the other half were assigned to observation (no medication). In the medication group, treatment reduced eye pressure by approximately 20 percent.

Contact: Betsy Nisbet, 734.647.5586, bsnisbet@umich.edu.