Glaucoma

August 18, 1999
Web posted at: 12:17 PM EDT (1617 GMT)

In this story: Description Risk Symptoms Treatment Prevention RELATEDS

From WebMD

DESCRIPTION

Glaucoma is a disease of the eye's optic nerve. This nerve, which relays visual information to the brain, consists of coarse fibers that arise in the retina and lead to the brain's visual cortex. Usually, the damage of glaucoma is caused by abnormally high intraocular pressure (IOP), or increased pressure inside the eye. In some cases glaucoma develops in people with normal IOP. Glaucoma can lead to blindness.

Most people with glaucoma have open-angle glaucoma, a chronic form of the disease. Open-angle glaucoma is caused by a gradual build-up of the eye's fluid, which puts pressure on the nerve fibers. A less-common type is closed-angle glaucoma, an acute form in which the iris of the eye suddenly pushes against the lens, causing a dramatic rise in IOP.

Normotensive glaucoma occurs in people with normal IOP. Although IOP is normal, the optic nerves are damaged. Normotensive glaucoma can be caused by an excess of glutamate, a neurotransmitter (chemical messenger between nerve cells).

Rarely, babies are born with congenital glaucoma, caused by improperly developed eyes.

RISK

People in these groups are at greater risk of glaucoma:

SYMPTOMS

Chronic open-angle glaucoma and normotensive glaucoma may not produce any symptoms until much damage has already been done. People with glaucoma may at first notice visual disturbances (such as trouble distinguishing shades of brightness and loss of peripheral vision), and their eyes may be sensitive to glare.

Symptoms of closed-angle glaucoma include sudden intense pain above one eye and blurred vision in that eye. The person may see halos around lights. Anyone experiencing these effects should seek medical help immediately.

TREATMENT

Glaucoma can only be treated effectively if it is diagnosed before the nerve fibers are completely destroyed. If glaucoma is caught early on, before it has done irreversible damage, medications as well as surgical options can help to restore IOP to normal levels. People with chronic glaucoma must use special eyedrops or other medication daily for the rest of their lives.

Some scientists believe that dronabinol, a drug made from the active chemical in marijuana, may be effective in reducing IOP. Studies are ongoing.

PREVENTION

Glaucoma can be prevented through early detection of elevated IOP. Intraocular pressure can be measured with a simple test called tonometry. Everyone, especially those at greater risk for glaucoma, should have a thorough eye examination (including tonometry) regularly.

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