Overview

Definition

Glaucoma is a group of diseases that damage the optic nerve. It is the optic nerve that carries visual information from the back of the eye (the retina) to the brain.

Clear fluid flows throughout a space in front of the eye called the anterior chamber. This fluid bathes and nourishes tissues. In glaucoma, fluid drains too slowly out of the eye. As the fluid builds up, the pressure inside the eye increases. This is called intraocular pressure (IOP). Unless this pressure is controlled, sight may be permanently damaged.

More than 2 million Americans have glaucoma yet many don't know they have it.

The five basic types of glaucoma are:

Chronic open-angle glaucoma. This is the most common form of glaucoma in the United States. The drainage angle of the eye doesn't work as well and pressure in the eye slowly increases, damaging the optic nerve. The person with open angle-glaucoma will frequently have no symptoms and it is usually detected on a routine eye exam. Treatment with medication or surgery is needed to stop vision loss.

Normal-tension glaucoma is believed to be related to poor blood flow to the optic nerve. These eyes seem to be susceptible to pressure-related damage even when fluid in the eye is in the high normal range.

Angle closure glaucoma. Some people's eyes include an iris (the colored part of the eye) that is too close to the drainage canal of the eye and can block the canal. When fluid cannot exit the eye pressure builds quickly. The quick onset of this condition causes severe eye pain or headache and may be accompanied by nausea and vomiting. Patients with angle closure glaucoma usually have a red eye with a cloudy center (cornea). Angle closure glaucoma is a medical emergency and treatment should be sought immediately.

Congenital. This affects children who are born with eye defects that slow normal fluid drainage.

Secondary glaucoma. This form develops as a complication of other medical conditions such as eye injuries, eye surgery, diabetes and corticosteroids.

Prognosis

Left untreated, you could have permanent vision loss and even blindness. Vision loss is irreversible. Glaucoma does not have a cure, but it can usually be controlled with medications or surgery. Early detection through routine eye exams can save your sight.

More on Glaucoma

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This article was reviewed and updated June 2007.