their families and friends. It provides information about open-angle glaucoma,
the most common form of glaucoma. This booklet answers questions about the cause
and symptoms of the disease and discusses diagnosis and types of
The National Eye Institute (NEI) conducts and supports research
that leads to sight-saving treatments and plays a key role in reducing visual
impairment and blindness. The NEI is part of the National Institutes of Health
(NIH), an agency of the U.S. Department of Health and Human Services.
What is glaucoma?
Glaucoma is a group of 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