People who take medication to treat glaucoma appear to outlive those who don't treat the eye disease, new research has found.
However, whether the reduced risk for premature death stems from the glaucoma drugs themselves or from the individuals' overall health or even their access to health care remains unclear.
Use of glaucoma drugs poses important questions for the more than 2 million Americans with the eyesight-threatening condition, which causes steady deterioration of the optic nerve, said Dr. Joshua D. Stein, an assistant professor of ophthalmology and visual sciences at the University of Michigan and lead author of a report on the research, published in the February issue of the Archives of Ophthalmology.
"There are four or five classes of drugs for ophthalmology, and they have side effects," Stein said. "Among other things, they can affect kidney function and blood pressure, so it's important to know whether drug therapy is beneficial or detrimental to overall health."
The study, which involved 21,506 people with glaucoma or suspected glaucoma, came down strongly in favor of drug therapy. It found that the drugs do not harm overall health. And, it discovered that those who regularly took glaucoma medications had a 74 percent reduced risk for early death, compared with those who didn't take the drugs.
But Stein stressed that those numbers say nothing about whether or why regular use of glaucoma drugs lowered the chances of dying. "The type of data we are working with can't answer that question," he said.
It's possible that the medications are beneficial, acting to boost kidney function, lower blood pressure or otherwise improve general health, he said. "But the fact that all the different classes of medications have the same benefit suggests to me that it might not be the medications themselves," Stein said. "It could be the types of patients who are receiving the medications. Patients who have more life-threatening conditions are less likely to get glaucoma treatment, so perhaps they are healthier people in general. Or perhaps it is access to care. Some people who don't have access to glaucoma care have less access to medical care in general."
The new study is the latest contribution to a long-running debate about whether glaucoma itself can increase the risk for death, said Dr. Louis Pasquale, director of the glaucoma service at Massachusetts Eye and Ear Hospital. A number of studies have come to differing conclusions on the issue, said Pasquale, who has published a meta-analysis of such studies.
"When you analyze them all together, it appears that glaucoma is associated neither with premature death or later-onset death," he said.
The latest finding is a valuable contribution to the debate, Pasquale said. "Dr. Stein has opened the eyes of researchers that medications need to be taken into account when trying to understand the relationship between glaucoma and mortality," he said.
Dr. Stuart McKinnon, an associate professor of ophthalmology and neurobiology at Duke University, said the finding reinforces the belief that glaucoma medications are safe.
"If I were talking to a patient, I would be cautiously optimistic, saying that the data base shows it possibly will help you but there is no harm in taking glaucoma eyedrops or other medications," McKinnon said.
However, participants in the study included relatively few black patients, who are more likely to have glaucoma, he noted.
"In terms of statistics, it is a real outcome, but you have to be careful how you apply it," McKinnon said. "That's my bottom line."
The U.S. National Eye Institute has more about glaucoma.