What You Should Know

Imagine How You Would See the World

Scene of two boys playing.
Normal vision.

Distored scene of two boys playing.
Same scene viewed by a person with glaucoma.

What is glaucoma?

Glaucoma is a group of eye diseases that can damage the eye’s optic nerve and result in vision loss and blindness. However, with early treatment, you can often protect your eyes against serious vision loss.

What is the optic nerve?

The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina to the brain. (See diagram below.) The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision.

Eye diagram.
A cross-sectional diagram of the eye, showing the optic nerve at the back (left side of diagram).

How does open-angle glaucoma damage the optic nerve?

In the front of the eye is a space called the anterior chamber. A clear fluid flows continuously in and out of the chamber and nourishes nearby tissues. The fluid leaves the chamber at the open angle where the cornea and iris meet. (See diagram below.) When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye.

Eye diagram.
Fluid pathway is shown in blue.

Sometimes, when the fluid reaches the angle, it passes too slowly through the meshwork drain. As the fluid builds up, the pressure inside the eye rises to a level that may damage the optic nerve. When the optic nerve is damaged from increased pressure, open-angle glaucoma—and vision loss—may result. That’s why controlling pressure inside the eye is important.

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