Risk Factors

An estimated 2 million Americans have open-angle glaucoma, but an exact count is unclear. Half of people with glaucoma are unaware of this problem because the condition causes no symptoms. Elevated intraocular pressure in the eye occurs in 5 to 10 million Americans but only about 10% of such people develop glaucoma because of this pressure. And, in 15% of actual glaucoma cases, IOP is normal. Major studies are helping to clarify the people who are at highest risk for glaucoma and optic nerve damage, including those with normal tension glaucoma.

Elderly. The prevalence of chronic glaucoma increases with age. In a major study, 0.6% of people aged 60 to 64 had primary open-angle glaucoma. Among people who were ten years older, the prevalence had more than doubled to 1.3%, and among those who were aged 80 to 84, it had more than doubled again to 3%.

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People of African Descent. Across all age groups, according to a 2000 report, the prevalence of glaucoma in African Americans is about 3.5% compared to about 1% in Caucasian Americans. In addition, US studies suggest that glaucoma develops earlier in African population groups (starting at age 45 instead of 60 in Caucasians). And, their risk for blindness once they have glaucoma is 14 to 17 times that of Caucasians with glaucoma. African American men are at higher risk than women are. African American children who are extremely near-sighted and have relatives with glaucoma should begin regular eye examinations for glaucoma as early as possible.

In a major glaucoma study in Barbados, where most people are of African descent, over 10% of those 50 and older had open angle glaucoma, and over 15% were afflicted after 70. About half of the cases had normal or lower eye pressure. There was an interesting 2001 study in which African Americans tended to have significantly thinner central corneas than Caucasians. This could lead to misleadingly lower pressure scores in African American patients who actually may have high IOPs.