March 11 (HealthDay News) -- Black people diagnosed and treated for glaucoma and those with high pressure in their eyes may be at increased risk for cardiovascular death, a new study suggests.

"Glaucoma is one of the leading causes of visual impairment worldwide," the researchers from Stony Brook University in Stony Brook, N.Y., wrote as background information in the study. "The most common type, primary open-angle glaucoma, is especially prevalent in populations of African origin, in which it is the foremost cause of blindness."

In addition to higher rates of open-angle glaucoma, blacks also tend to have higher rates of high pressure in their eyes (ocular hypertension) and higher rates of death from chronic disease than whites, the study authors noted.

They analyzed data on 4,092 people, aged 40 to 84 (average age 58.6), who took part in the Barbados Eye Studies of a predominately black population with similar ancestry to black Americans.

During the initial study visits that took place between 1987 and 1992, participants' height, weight and blood pressure were recorded, they were interviewed, and various eye measurements -- including photos of the retina and eye pressure assessments -- were taken.

At the start of the study, 300 participants had glaucoma, including 141 who'd been diagnosed and treated. After nine years of follow-up, 764 (19 percent) of the participants had died.

After the researchers adjusted for other factors, they concluded that glaucoma was not associated with risk of death overall. However, they did find that the risk of cardiovascular death was: 28 percent higher in those with ocular hypertension at the start of the study; 38 percent higher in people who'd previously been diagnosed with or treated for open angle glaucoma; and 91 percent higher in those who'd been treated with a beta blocker drug called timolol maleate.

The findings were published in the March issue of the Archives of Ophthalmology.

"One explanation for the excess mortality [death] found in persons with previously diagnosed open-angle glaucoma could be their longer duration of disease compared with those with newly diagnosed disease," the study authors wrote. "Another explanation for an increased mortality risk could be related to the open-angle glaucoma treatment received."

They noted that inappropriate use, or adverse effects, of beta blockers and other medications used to treat glaucoma may damage the cardiovascular system. They also said there's some evidence that risk factors for ocular hypertension and cardiovascular disease are similar.

"These findings underscore the importance of close monitoring and controlling of adequate intraocular pressure levels in this and other high-risk populations," the researchers concluded.

SOURCE: JAMA/Archives journals, news release, March 10, 2008