Schuman said there are a number of ways that diabetes could increase the risk of glaucoma. One way is by causing elevation in pressure within the eye. Or it's possible, he said, that diabetes could increase the susceptibility of the optic nerve to damage.
He said there's also one form of glaucoma that's known to be directly related to diabetes -- neovascular glaucoma. In this type of glaucoma, there's a reduction of oxygen supply to the retina, which causes the retina to send out signals for more oxygen and for new blood vessels to form. When these new blood vessels form, they cause scarring and block the normal drainage system in the eye, causing pressure to build up in the eye.
The most important thing someone with diabetes can do to protect their eyes is to get regular eye exams, Schuman said. Glaucoma generally has no early symptoms.
"There's no way to detect glaucoma without an exam, and the only way to prevent the loss of vision from glaucoma is to treat the disease early. You can't get back nerve damage that's been lost," he said.
Diabetes specialist Dr. David Oyer, of Northwestern Memorial Hospital in Chicago, said he recommends that people with diabetes have their eyes checked once a year by an ophthalmologist for glaucoma and other serious eye diseases associated with diabetes.
"The most important thing for reducing your risk of complications is to keep your blood sugar down both pre- and post-meal," Oyer said. He also recommends getting your A1C level checked every three to six months and keeping that number below seven, preferably below 6.5. A test of A1C (also known as glycated hemoglobin, or HbA1c) provides a snapshot of your average blood glucose control for the past two to three months, according to the American Diabetes Association.
Schuman also said regular exercise might help. "Exercise is good for the eye, just as it is for the rest of the body. Regular, vigorous exercise does lower eye pressure and probably affects circulation to the eye," he said.
More information
To learn more about glaucoma, visit the National Eye Institute.
