Glaucoma, one of the leading causes of blindness among adults, is perhaps the textbook definition of “insidious,” its presence often not noted until the damage is done.
“It’s painless and it happens gradually,” said Dr. Charlotte Akor, an ophthalmologist at Hendrick Medical Center.
And gradually Akor said, sometimes can mean decades.
There is no cure, but treatment may be possible with early detection, according to the National Eye Institute. Vision lost to glaucoma, however, cannot be restored.
The statistics tell a grave story.
According to the Glaucoma Research Foundation, more than 3 million Americans are estimated to have glaucoma, but only half of them are aware of it. More than 120,000 people in the U.S. are blind from it (the World Health Organization recognizes it as the second-leading cause of blindness worldwide). African-Americans are 15 more times more likely to be visually impaired by glaucoma, and blindness from glaucoma is six to eight times more likely among African-Americans than among Caucasians.
Glaucoma is a group of eye diseases that harm the optic nerve, most usually caused by abnormally high pressure in the eye. Normally, fluid in the eye, called aqueous humor, flows out of the eye through a mesh-like channel. Glaucoma is caused when the channel gets blocked.
Akor said the cause of the blockage is unknown, but glaucoma is a hereditary disease. Although it can affect a person at any age, she said, the onset usually occurs after 50.
Most people don’t know they have it unless it’s diagnosed, she said.
“It’s a silent disease,” she said. “Glaucoma affects how much you see, and you don’t notice it at first.”
Akor said glaucoma affects peripheral vision. Unlike with cataracts, the vision loss is irreversible.
“With cataracts, you have them removed and then you can see again,” she said. With glaucoma, “after you lose your vision, you can’t bring it back.”
The most common type of glaucoma is called open-angle and occurs when the drain structure of the eye is blocked. Akor said the condition is genetic but that race and age appear to be major factors.
Open-angle glaucoma can be treated with laser surgery, which can increase the flow of fluid from the eye, or a type of microsurgery known as a trabeculectomy, which actually creates a new channel to drain fluid.
The most common form of treatment, however, is eye drops, Akor said. She said that treatment generally is successful, under two conditions: the condition is diagnosed relatively early and patients actually use the treatment.
The best way to test for glaucoma, Akor said, is to dilate the pupil with eye drops then check the optic nerve to see whether it looks abnormal.
A doctor also can perform a test, called tonometry, to determine the pressure in the eye. A field vision test can determine whether a patient has lost peripheral vision. The test doesn’t take much time and isn’t painful.
Akor said anyone who is older than 50, has a family history of glaucoma, or has other factors predisposed to glaucoma, needs to have annual eye exams.
“At age 50, you should have your eyes checked every year,” she said. “People with glaucoma have it 10, 20 even 30 years before they notice it. That’s why screening is so important.”