February 15, 2011

Obesity May Lower Glaucoma Risk In Women

New research finds that older, overweight women may be at lower risk for glaucoma than their thinner peers.

The study published in the Archives of Ophthalmology involved some 4,000 older Dutch women who were followed for ten years.  The researchers found that the heavier female participants were less likely to develop the blinding eye disease known as open-angle glaucoma. 

A similar link between weight and glaucoma was not observed among the men in the study.
Open-angle glaucoma, the most common form of the disease, occurs when fluid buildup exerts pressure in the eye, damaging the optic nerve that runs from the eye to the brain.

"Open-angle glaucoma is a chronic eye disease characterized by glaucomatous optic neuropathy and corresponding glaucomatous visual field loss," wrote the study's authors. 

Previous research has identified several risk factors for open-angle glaucoma, including intraocular pressure (pressure within the eye), age, sex, myopia (nearsightedness) and ethnicity.

Dr. Wishal Ramdas of the Erasmus Medical Center, Rotterdam, the Netherlands, and colleagues examined data from 3,939 participants in the Rotterdam Study.  This population-based study included participants 55 years of age and older who did not have open-angle glaucoma when the study began between 1991 and 1993.

Over an average of 9.7 years of follow-up, 108 participants (2.7 percent) developed open-angle glaucoma.  Those who developed the condition were significantly older, more often had high myopia (severe nearsightedness) and were more often male, compared with those who did not.

No statistically significant effect of socioeconomic status, smoking or alcohol intake was found on the development of open-angle glaucoma.

Among the female participants, there was a significant association observed between increased body mass index and intraocular pressure, with each one-unit increase in body mass index associated with a 7 percent decreased risk of developing open-angle glaucoma. These associations were not present in men.

The study's findings were somewhat counterintuitive, since the overweight and obese female participants had slightly greater intraocular pressure, which should have resulted in an increased risk for glaucoma.

"However, this effect was not observed and thus the multivariate analysis yielded a protective effect of body mass index on open-angle glaucoma incidence in women," the study's authors wrote.

The researchers speculated that there may be something protective about added fat tissue in women, such as increased levels of estrogen, that may help lower the risk of glaucoma.

"High estrogen levels and hormone therapy might be protective to open-angle glaucoma, and obesity seems to be positively related with postmenopausal plasma estrogen levels."

"Obesity appears to be associated with a higher intraocular pressure and a lower risk of developing open-angle glaucoma," they concluded.

"These associations were only present in women. Other lifestyle-related factors, such as socioeconomic status, smoking and alcohol consumption, were not associated with open-angle glaucoma."

Despite the findings, no one is suggesting that women gain weight to ward off glaucoma.

"The best way to prevent vision loss from the disorder is to have regular eye exams and, if glaucoma is found, early treatment," said Dr. Johannes R. Vingerling, one of the researchers involved with the study.

"The best therapy is to lower eye pressure in these people," he told Reuters, adding that this can be accomplished with medicated eye drops or surgery.

Eye exams are particularly important for those with an elevated risk of glaucoma, such as those over the age of 60 or with a family history of glaucoma. Mexican Americans and African Americans are also at higher risk, Dr. Vingerling said.

Just half of the estimated four million Americans with glaucoma are aware of their condition. 

The American Academy of Ophthalmology recommends that all adults begin having routine comprehensive eye exams at the age of 40.  Those at higher risk of glaucoma may be advised to have exams earlier, or more frequently.

The study was published online February 14 in the Archives of Opthamology.


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