What is Glaucoma?

Glaucoma is a group of diseases that can damage the eye's optic nerve and result in vision loss and blindness. While glaucoma can strike anyone, the risk is much greater for people over 60.

How Glaucoma Develops

There are several different types of glaucoma. Most of these involve the drainage system within the eye. At the front of the eye there is a small space called the anterior chamber. A clear fluid flows through this chamber and bathes and nourishes the nearby tissues.

In glaucoma, for still unknown reasons, the fluid drains too slowly out of the eye. As the fluid builds up, the pressure inside the eye rises. Unless this pressure is controlled, it may cause damage to the optic nerve and other parts of the eye and result in loss of vision.

Open-angle Glaucoma

The most common type of glaucoma is called open-angle glaucoma. In the normal eye, the clear fluid leaves the anterior chamber at the open angle where the cornea and iris meet. When fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye.

Sometimes, when the fluid reaches the angle, it passes too slowly through the meshwork drain, causing the pressure inside the eye to build. If the pressure damages the optic nerve, open-angle glaucoma -- and vision loss -- may result.

There is no cure for glaucoma. Vision lost from the disease cannot be restored. However, there are treatments that may save remaining vision. That is why early diagnosis is important.

See this graphic for a quick overview of glaucoma, including how many people it affects, who’s at risk, what to do if you have it, and how to learn more.

See a glossary of glaucoma terms.