By: Kimberly Dent-Ferguson, MBS, MPH, CPMC Research Analyst
Reviewed by: Ravi D. Goel, MD, Regional Eye Associates and Wills Eye Institute and Tara Schmidlen, MS, LCGC, Coriell Institute for Medical Research

What is Glaucoma?

Glaucoma is an eye condition which may cause progressive optic nerve damage and corresponding vision loss. The eye is like a camera. Visual images stimulate the retina, a light sensitive tissue at the back of the eye that acts as the camera's film. This "film" is then "developed" when the retina sends nerve impulses to the visual centers in the brain via the optic nerves. The anterior chamber of the eye is the space between the iris and the cornea that is filled with a fluid called aqueous humor. This fluid normally drains through tissues at the anterior chamber's angle, where the iris and cornea meet. Aqueous humor overproduction or a poor drainage system can lead to increased eye pressure and optic nerve damage.

There are several types of glaucoma. Two common forms include primary open-angle glaucoma and angle-closure glaucoma. Angle-closure glaucoma develops quickly. During an angle-closure glaucoma attack, the iris and the cornea block the drainage canals, which results in a sudden rise in eye pressure. In primary open-angle glaucoma there is a wide, open angle between the iris and cornea and an overproduction of fluid or decreased fluid flow through the drainage canals results in a gradual increase in eye pressure.

Primary open angle glaucoma is the most common type of glaucoma and has been referred to as the "silent thief of sight" because its onset is so subtle and gradual that permanent visual loss often occurs without warning signs or symptoms1. The CPMC has tested variants rs7049105 and rs7518099, which are associated with primary open-angle glaucoma.

Primary open-angle glaucoma is more severe and develops at an earlier age in African Americans. Early diagnosis and treatment of glaucoma can minimize or prevent optic nerve damage and limit glaucoma-related vision loss.

How Common is Glaucoma?

Glaucoma is the second leading cause of blindness in the world. In the United States, there are 3 million individuals with primary open-angle glaucoma. About 120,000 Americans are blind as a result of glaucoma2.

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Learn more about Glaucoma, from symptoms to understanding your risk, through the links below.

Page References

1. Hazin, R. and A.M. Hendrick, Primary open-angle glaucoma: Diagnostic approaches and management. Journal of the National Medical Association, 2009. 101(1): p. 46-50.
2. Glaucoma Research Foundation. Glaucoma Facts and Stats. 2013 April 22; Available from:

Symptoms, Diagnosis, Treatment

Learn more about Glaucoma Learn More› ]

Risk Factors

Both genetic and non-genetic factors play a role in Glaucoma
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Reduce Your Risk

Risk-reducing behaviors for Glaucoma Learn More› ]

The CPMC Study

Learn how the CPMC Study identifies your risk for Glaucoma Learn More› ]