A type of “dandruff” that has nothing to do with the unsightly scalp malady can rob you of your vision—and now a new study has revealed surprising risk factors, including where you reside. Northerners in particular need to take note! We’re talking about exfoliation glaucoma (EG), a common eye disease in which flakes of abnormal dandruff-like material build up on the front of the lens and clog the eye’s drainage system, leading to an increase in eye pressure that can damage the optic nerve and cause permanent vision loss.

To figure out who is most likely to develop EG, researchers analyzed data on more than 120,000 US women and men ages 40 and up, following the participants for more than two decades and tracking who was diagnosed with or strongly suspected of having the disease. Researchers discovered that EG risk is affected by…

Place of residence. Most likely to develop EG were people who resided for most of their lives in the northern tier of the US, above the 41° to 42° latitude (for instance, in states north of or on par with Connecticut, Nebraska and Oregon). Compared with Northerners, risk was reduced 75% for people living in the southern tier, below the 37° latitude (for instance, in states south of or on par with North Carolina, Arkansas and Arizona)…for those in the middle tier, risk was reduced 47%.

Gender. Compared with men, women were about three times more likely to get EG…also, women tended to develop the disease several years earlier than men.

Family history. EG risk was more than doubled among participants who had a close relative with any type of glaucoma.

Age. Participants over age 75 were 46 times more likely to have EG than people ages 40 to 55.

Surprising: Although people of Scandinavian ancestry have long been thought to be at increased risk for EG, this study found no ethnic association…nor did eye color appear to affect risk.

Insights: Like other forms of glaucoma, EG generally produces no early warning signs that patients are likely to spot on their own until after irreversible optic nerve damage has already occurred—yet early diagnosis and treatment are key to preserving vision. That’s one reason why the American Academy of Ophthalmology recommends getting an eye exam every year or two after age 65. This is important advice for everyone…and especially, it now appears, for women living in northern climes.