Results of the five-year study were published in the June 2002 issue of Archives of Ophthalmology.
"There are several risk factors linked to the development of glaucoma, and this study has helped us to define how much benefit we can provide by decreasing eye pressure with eye drops," said Dr. Ronald L. Gross, a professor of ophthalmology at Baylor College of Medicine in Houston and an investigator in the study.
Open-angle glaucoma is one of the leading causes of blindness in the United States and the number one cause of blindness among African Americans. The disease often occurs when fluid builds up, causing pressure in the eye to increase. When this pressure damages the optic nerve, glaucoma and vision loss are the result.
The National Ocular Hypertension Treatment study evaluated 1,636 people ranging in age from 40-80 with elevated pressure in the eye, with no signs of glaucoma damage. Half received daily eye drops, while the other half were given no medication. For those who received the medication, eye pressure decreased by approximately 20 percent.
Researchers found that the risk for developing primary open-angle glaucoma was cut by more than 50 percent for those individuals who used the eye drops. The study showed that 4.4 percent of the study participants receiving the drops developed glaucoma over a five-year period, while 9.5 percent of the participants who did not receive the drops developed glaucoma. Additionally, study participants with several risk factors were found to be more likely to develop the disease. These included age, race, and a family history of glaucoma, as well as ocular risk factors including elevated eye pressure, corneal thinness and certain characteristics in the anatomy of the optic nerve.
"Glacoma is often referred to as the 'sneak thief of sight' because it often occurs with no pain or symptoms," said Gross, also the Clifton R. McMichael chair of ophthalmology at Baylor. "Many times patients don't notice a difference in peripheral vision until the problem has progressed, therefore, it is essential to visit an ophthalmologist to detect the condition early."
The 22-center study was supported by the National Eye Institute, The National Center on Minority Health and Health Disparities, Research to Prevent Blindness and Merck Research Laboratories.