With an Eye to Your Homeland

Glaucoma risk factors include gender and what latitude you live in

(RxWiki News) Heading south, young men and women? It may be better for your eyes - or at least put you at a lower risk for developing one form of glaucoma.

A new study has shown that people living in higher latitudes have a greater likelihood of developing exfoliation glaucoma even when other demographic factors are taken into account.

"Get annual eye exams to test for early signs of glaucoma."

Lead author Jae Hee Kang, of the Channing Laboratory at Harvard Medical School and of Brigham & Women's Hospital in Boston, led the multi-decade study to look at possible risk factors for exfoliation syndrome, a leading cause of glaucoma that can also increase risk for cataracts.

They found that living most of your life in the southern third of the U.S. decreased the risk of developing the condition by 75 percent compared to living in the northern third. Living in the middle decreased risk by 47 percent.

Where a person lived when they were 15 years old played the biggest role in determining their risk, followed by their current geographic residence.

"Another manuscript we published recently suggests that lower ambient temperature interacts with increased solar exposure to increase the risk of exfoliation syndrome," said Louis Pasquale, MD and a study co-author who directs the Massachusettes Eye and Ear's Glaucoma Center of Excellence.

"More work is needed to determine how environmental factors conspire to contribute to exfoliation syndrome," he said.

For the study, researchers tracked 78,955 female health professionals from 1980 through 2008 and 41,191 male health professionals from 1986 through 2008.

All participants were aged 40 or older, did not show symptoms of glaucoma at the start of the study and lived in the U.S. Most were white, so the study could not compare exfoliation glaucoma risk across different ethnicities.

The participants provided information about their geographical residence throughout their lifetimes. Within the total group, 348 developed glaucoma.

Adding to evidence found in previous studies that age is a risk factor, those aged 75 and older had a higher risk of developing glaucoma than those between the ages of 40 and 55.

Men were 68 percent less likely to develop exfoliation glaucoma or early symptoms of the disease.

Researchers could not determine whether women had a higher risk because of biological gender differences or because of possible lifestyle differences between the men and women in the study.

“This is an excellent study which confirms what many doctors have observed for years," said Dr. Christopher Quinn, an optometrist from Omni Eye Associates who was not involved in the study.

"Pseudoexofoliative glaucoma, like other forms of open angle glaucoma, occurs with no symptoms like pain or blurred vision," Quinn said.

"More than half of the patients with glaucoma don’t know they have it, and a comprehensive eye exam by an eye doctor with dilation of the pupils is the best way to identify all forms of glaucoma before irreversible vision loss occurs," he said.

The study revealed that a person's ancestry did not influence his or her risk of developing the condition. Scientists previously thought those of Scandinavian descent may be at higher risk because the rates of exfoliation glaucoma are higher in those countries than in others.

A person's eye color also did not appear to be a risk factor, but having a family history of the disease doubled the likelihood that someone would develop it.

The study appears in the January issue of Ophthalmology. The study was funded by the National Institutes of Health, the Arthur Ashley Williams Foundation and the Harvard Glaucoma Center of Excellence. The authors stated they have no financial interests associated with the study content.

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Review Date: 
January 11, 2012