By Nancy Shute, NPR
Taking birth control pills may increase a woman’s risk of eye disease later in life, a study finds, because they may reduce protective levels of estrogen.
Estrogen affects cells in the eye’s retina, which may help explain a possible link between glaucoma and estrogen levels.
Doctors have long known that cells in the eye have estrogen receptors. But in the past few years they’ve started looking into whether the changes in a woman’s estrogen levels as she goes through life could affect her risk of glaucoma .
The eye disease slowly damages the optic nerve and is most common in people over 40. There are treatments that can slow its progression, but there is no cure.
In this study, researchers looked at data on 3,406 women over 40 who participated in a big national health survey administered by the Centers for Disease Control and Prevention. The women who had taken oral contraceptives for more than three years were more than twice as likely to be diagnosed with glaucoma.
But the absolute risk of getting glaucoma after age 40 is small, about 1.86 percent, according to the CDC. So doubling that risk would bring it up to a bit under 4 percent.
And there’s no proof that taking birth control pills , which contain hormones that keep estrogen levels from peaking midway through a woman’s monthly cycle, cause the apparent increased risk.
There could be a relationship between eyesight and estrogen, though. Scientists have long thought that the hormone could have a protective effect on the eye’s retina. So it makes sense that the pill, which lowers a woman’s total exposure to estrogen over a month, could affect her eyes, says Dr. Shan Lin , a professor of clinical ophthalmology at the University of California, San Francisco, and senior author of the study.
Read the full story by Nancy Shute from NPR.
