AARP Hearing Center
The facts about glaucoma can seem a little scary: It’s the second leading cause of blindness worldwide, affects about 3 million Americans and becomes more common with age. Yet half of the people in the United States who have glaucoma don’t know it, according to the federal Centers for Disease Control and Prevention (CDC).
One big reason so many people are in the dark: In its most common forms, glaucoma has no symptoms until the damage is well underway. In a typical case, the optic nerve at the back of the eye, which sends visual information to the brain, becomes more and more damaged over time, often because of high pressure in the eye. The damaged nerve fibers slowly eat away at peripheral, or side, vision — something people rarely notice, eye experts say.
“It’s almost always silent,” says Shivani Kamat, M.D., an assistant professor of ophthalmology at UT Southwestern Medical Center and a spokesperson for the American Academy of Ophthalmology. “A lot of people don’t notice vision loss themselves until they’ve lost over 50 percent.”
One reason peripheral vision loss is so sneaky is that our brains tend to “fill in” the missing picture parts, says Thomas Brunner, president and CEO of the Glaucoma Research Foundation.
Only in its advanced stages does the most common type of glaucoma, open-angle glaucoma, affect central vision, which is needed for reading and many other daily tasks.
A less common form, called angle-closure glaucoma, can sometimes have dramatic, immediate symptoms (see below).
But the best way to detect most early signs of glaucoma, along with other eye problems, is to get regular eye exams, according to the ophthalmology academy and the American Optometric Association. The U.S. Preventive Services Task Force says more research is needed on screening for glaucoma.
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