It often develops slowly, gradually stealing vision before a person notices he or she has a problem. It can eventually cause blindness if left untreated.
In The Early Show eye health series, Dr. Emily Senay explains that glaucoma damages vision when pressure in the liquid that circulates in the open spaces within the eye puts pressure on the optic nerve that carries information from the eye to the brain.
There are several types of glaucoma, but the most common form involves a gradual buildup of eye pressure that may not have any symptoms, such as vision loss or pain, until it reaches an advanced stage.
The good news is that there is a quick and easy screening test to measure eye pressure that can catch glaucoma early on.
There's no cure, but there are effective medications -- usually in the form of eye drops -- and laser surgery options that can manage the disease effectively. Once you are diagnosed, you need to stay on top of it for life to control its progression and prevent vision loss.
Anyone can develop glaucoma, but there are higher risk groups.
It's more common among people over 55. People with a family history of the disease and African-Americans are at higher risk, and may develop it earlier.
Other risk factors include high blood pressure, diabetes, nearsightedness, a history of high eye pressure and previous eye injury or surgery. Excessive alcohol use and chronic steroid use can also raise the risk of glaucoma.
As for warning signs, in many cases, the disease creeps up slowly and steals away peripheral, or side vision.
Other signs that might be an indication of glaucoma include an inability to adjust the eye to darkened rooms, difficulty focusing on close work, rainbow colored rings or halos around lights, and frequently needing to change your prescription for glasses.
People over 20 should have an eye exam that includes a test for glaucoma every two years until age 64 then every year thereafter. People at higher risk should consult with their doctor about more frequent screening.