What It Is: A silent vision thief, glaucoma occurs when a drainage area gets blocked, preventing fluid in the eye from draining. The upshot: Eye pressure rises, damaging the optic nerve permanently. An estimated 2.3 million people have been diagnosed with glaucoma and another 2 million don't know they have it.
Symptoms: With the most common form, open angle glaucoma, there are virtually no symptoms before vision loss occurs. As the disease progresses blank spots appear in your field of vision and become larger with further damage to the optic nerve.
How It's Treated: If your eye pressure is on the high side, you'll be monitored; if pressure keeps climbing, prescription eye drops help lower it. Laser surgery can improve the flow of fluid from the eye. Surgery to create a new drainage area can also be performed.
How to Prevent: You can't. It's more common in people 60 and older and in African-Americans. The good news: "We do a pretty good job of treating people, so you're unlikely to lose your vision under a doctor's care. But early detection is crucial," says Dr. Kaiser.