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Definition
Glaucoma is a group of diseases that damage the optic nerve, which 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.
Nearly 120,000 Americans are blind from glaucoma and at least another 3 million have the disease. Half of those with glaucoma 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.
Closed-angle glaucoma. Some people's eyes are formed with the iris (the colored part of the eye) too close to the drainage angle of the eye. The iris can be sucked into the drainage angle and block it completely. The fluid cannot exit the eye, causing pressure to build quickly. This causes severe eye pain or headache, usually associated with nausea and vomiting. Patients usually have an angry red eye with a cloudy center (cornea) This is a medical emergency.
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 What Is Glaucoma?
How Is Glaucoma Diagnosed?
How Is Glaucoma Treated?
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This article was reviewed June 2005, by Stephen Colucciello, MD, Clinical Professor of Emergency Medicine, University of North Carolina Medical School, Chapel Hill.
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