Causes

No single factor has been identified as a cause of primary open-angle glaucoma. A number of conditions, alone or in combination, are needed to trigger the processes leading to pressure in the first place and then to the nerve damage that destroys sight. The damage done to the optic nerve in glaucoma is triggered in most cases by the excessive pressure on the optic nerve that, over time, causes damage. Because optic nerve damage occurs in patients with normal as well as high intraocular pressure, however, researchers are investigating a number of other abnormal events that occur and can damage the optic nerve.

Genetic Factors

A number of genes have now been identified as possible factors in many cases of glaucoma. A gene called MYOC is of particular interest. Defects in this gene occur in between 3 - 6% of patients with adult-onset and juvenile open-angle glaucoma. They appear to overproduce a sticky protein called myocilin, which clogs the trabecular meshwork. The genes WDR36 and OPTN may cause primary open-angle glaucoma. Researchers hope that identification of genes will help improve screening of high-risk patients.

Syndromes Associated with Increased Optic Pressure and Glaucoma

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Specific syndromes have been identified with glaucoma. Many have an inherited component, although in most cases, other factors must be present to activate the disease process.

Pseudoexfoliation Syndrome. Pseudoexfoliation (PEX) syndrome (also known as exfoliation syndrome) is the most common identifiable condition associated with glaucoma. In one study, 9% of patients with open-angle glaucoma had the syndrome. PEX occurs when dandruff-like matter flakes off the outer layer of the lens and collects in the drainage angle. The substance is composed of proteins produced by the lens, iris, and other parts of the eye. People can have this condition and not develop glaucoma, but they are at high risk. In one Australian study, 14% of the people with this condition had glaucoma compared to 2% of those without exfoliation. PEX has a strong genetic component but other factors (possibly sunlight, an autoimmune response, or slow virus) may be needed to trigger the disease.