When eye doctors identify patients with a suspected case of glaucoma, they often choose to keep a close watch on the patients, rather than treating them with one of several medications available.

That’s because numerous side effects can accompany use of these drugs, including potential breathing and kidney function problems.

But according to University of Michigan research, when both glaucoma or suspected glaucoma patients take medications for the eye disorder, they have a significantly decreased risk of dying than patients who didn't take medication.

In the study, researchers looked at a database of more than 21,000 people older than 40 with glaucoma or suspected glaucoma in a managed care program. While glaucoma patients can also be treated with a laser therapy and with surgery, the study looked specifically at medications.

Those taking medications had a 74 percent decreased risk of dying, clearly demonstrating a link between taking glaucoma medication and glaucoma patient mortality, said Joshua Stein, a U-M assistant professor of ophthalmology and visual sciences and author of the study.

“It’s hard to sort out why,” said Stein, a glaucoma specialist at the U-M Kellogg Eye Center.

That's because several reasons can explain why patients may have a lower risk of death - and that may or may not include the medication itself, he said.

Joshua Stein is an assistant professor of ophthalmology and visual sciences at U-M.

For example, possible explanations might include the fact that patients dealing with other, more serious illnesses are more likely to delay treatment of the less serious ailment of glaucoma. It could also indicate those with less access to good health care in general are also less likely to get proper treatment for their glaucoma, Stein said.

It's also not fully understood whether glaucoma in general is associated with an increased risk of death because so many of those impacted are older patients with additional health problems, he said.

The study was published online in the Archive of Ophthalmology.

Further studies are needed to better understand the link, Stein said.

Tina Reed covers health and the environment for AnnArbor.com. You can reach her at tinareed@annarbor.com, call her at 734-623-2535 or find her on Twitter @TreedinAA.