This condition is the second leading cause of adult blindness. It results from intraocular pressure (IOP) within the eye that is too high for the optic nerve to tolerate. In almost all cases, glaucoma is "open angle," a condition which progresses slowly and is often undetected until its late stages. In these cases, it's believed that partial blockages of aqueous humor drainage (clear eye fluid) occur; this increases IOP, compresses fibers in the optic nerve and leads to a gradual loss of vision.

There are two primary risk factors for glaucoma—race and age. African Americans and Hispanics are most susceptible. About ten percent of whites over the age of 70 develop glaucoma; African Americans in the same age range are twice as likely to be afflicted. People with especially thin corneas are also at risk, as are people with a history of prolonged corticosteroids and nicotine use.

Regular eye check-ups can help catch glaucoma—and damage to the optic nerve—in its early stages. Glaucoma is a disorder that can be controlled. The overall goal of treatment is to reduce IOP and prevent damage to the optic nerve. In many cases, this can be accomplished with medication and/or laser surgery. When surgery is necessary or desired, the ophthalmologist reduces IOP by improving drainage of aqueous humor. Performed on an out-patient basis, the procedure takes less than an hour and is considered relatively safe and long-lasting.

For more information on glaucoma and treatment:
All About Vision
usnews
American Foundation for the Blind