A new study conducted by researchers at the Harvard University suggests that overweight women are at a lower risk than their slimmer counterparts to come down with the blindness-causing eye disease called glaucoma.

The researchers studied data from 78,777 women in the Nurses' Health Study and 41,352 men in the Health Professionals Follow-up Study. After a detailed analysis, they found that each unit increase in body mass index (BMI) was associated with a six percent lowered risk for normal-tension glaucoma one of the most common age-related eye diseases.

Also, women with a high BMI when they were young had reduced risk of developing normal-tension glaucoma. The researchers, however, found no association between BMI and the risk for POAG in men.

"While being overweight has many negative health consequences, increased risk of primary open-angle glaucoma was not one of them," says lead researcher Dr. Louis R. Pasquale, director of the Glaucoma Service at the Massachusetts Eye and Ear Infirmary and an associate professor of ophthalmology at Harvard Medical School.

"While this study represents a comprehensive assessment of the relation between body shape and glaucoma, it should not lead to recommendations about adopting an ideal body weight to prevent glaucoma," he says in the report published in the August issue of Ophthalmology.

The findings may have limitations since most of those in the study were white Europeans, the authors noted. Glaucoma is caused by increased pressure in the eye and is linked to optic nerve damage.

Effective treatments to control eye pressure are available. But in people with normal-tension glaucoma, optic nerve damage happens even though their eye pressure is not high, the researchers noted.

"There is no stereotypical body shape associated with primary open-angle glaucoma, but the negative relation we found between body mass index and the normal-tension variant of primary open-angle glaucoma in women may give some clues regarding eye-pressure independent mechanisms of optic nerve deterioration in this disease," says Pasquale.

"We postulate that fatty tissue in the body may release hormonally related signals that help prevent optic nerve deterioration in glaucoma," he says.