Glaucoma is one of the leading causes of blindness. And women who use birth control may be at greater risk than those who don't.
A recent study found that women who took oral birth control for three or more years had increased odds of having glaucoma.
The researchers also found that age, race, eye health history and age of first menstrual period were associated with increased odds of glaucoma.
The lead author of this study was Shan Lin, MD, from the University of California, San Francisco in California.
The study assessed 3,406 women who were part of the 2005 to 2008 National Health and Nutrition Examination Survey (NHANES). The women were selected for the current study because they completed the vision and reproductive health questionnaire and took an eye exam as part of the NHANES.
All of the participants were 40 years old or older.
Cases of glaucoma had been self-reported on the NHANES questionnaire. The participants also had provided sociodemographic information (age, ethnicity, education level, income), current and past health history, smoking and alcohol patterns, eye-related health history and reproductive history including use of oral birth control.
There were 231 women with glaucoma and an average age of 57.1 years old. There were 3,175 women without glaucoma, with an average age of 68.5 years old.
The findings showed that 2.3 percent of the glaucoma group had never used oral birth control, 1.3 percent had used oral birth control for less than three years and 1.4 percent had used it for three or more years.
Of those without glaucoma, 29.6 percent had never used oral birth control, 28.8 percent had used it for less than three years and 36.5 percent reported using oral birth control for three or more years.
Of the total study population, 31.4 percent reported never using oral birth control, 30.1 percent used it for less than three years and 37.9 percent had used it for three or more years.
After considering all the outside factors, the researchers determined that the women who reported using oral birth control for three or more years had 2.05 times increased odds of having glaucoma.
The findings revealed that birth control was not the only thing associated with a higher risk of glaucoma.
Older age was associated with 1.06 times increased odds of having glaucoma.
African American participants had 3.34 times increased odds of having glaucoma.
The participants who reported a history of retinopathy (eye condition that can cause blindness) were found to have 2.84 times increased odds of glaucoma.
Lastly, the researchers discovered that older age at first menstrual period was associated with 1.14 times increased odds of glaucoma.
According to the researchers, there is a need for more research to investigate the potential cause-and-effect relationship between oral birth control and glaucoma in the United States.
“This is an interesting study which identifies use of oral contraceptives for greater than 3 years as a previously widely unrecognized risk factor for the development of glaucoma," said Christopher Quinn, OD, optometrist at Omni Eye Services.
"Further study will be needed to confirm this information and help researchers understand the physiologic basis for the relationship discovered," said Dr. Quinn. "The study underscores an important public health message however. Get an annual eye examination. Since the most common forms of glaucoma cause no symptoms until the disease is very advanced, the only way to know if you have glaucoma is through a comprehensive eye exam. The doctor will be able to assess all of your risk factors for this potentially blinding disease and initiate treatment promptly should it be necessary."
This study was presented November 18 at the 117th Annual Meeting of the American Academy of Ophthalmology.
The National Eye Institute, Research to Prevent Blindness, That Man May See Inc. and the National Natural Science Foundation of China provided funding.