Glaucoma

Description

Risk Factors

An estimated two 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 five 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%.

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.

Family History. Glaucoma tends to run in families. One 1999 study reported that people with family histories of glaucoma are a third more likely to have already sustained visual loss when diagnosed with glaucoma than those first diagnosed who have no such history.

Effects of Blood Pressure. The association between a person's blood pressure and intraocular pressure in the eye is not entirely clear. A number of studies have found a higher risk for glaucoma in people with high blood pressure. A 2002 study suggests, however, that people with blood pressure that is low relative to their intraocular pressure may be at higher risk for glaucoma. The same study found no higher risk for glaucoma in people with hypertension, and in fact, high blood pressure was associated with a lower risk.

Having Certain Medical Disorders. Individuals with certain medical or physical conditions, including diabetes, migraine, nearsightedness, and sleep apnea, appear to have a higher risk. Conditions that require the use of any oral or inhaled steroid, particularly high doses for prolonged periods of time, can cause glaucoma. Previous eye surgery also puts people at risk.

Risk Factors for Other Forms of Glaucoma

Risk Factors for Closed-Angle Glaucoma. Chronic closed-angle glaucoma tends to be more common in people of Asian and African descent. Those who have this condition are often extremely farsighted. Acute closed-angle glaucoma occurs much more frequently in women than in men.

Risk Factors for Normal Tension Glaucoma. Risk factors for normal tension glaucoma include Japanese ancestry and a family history of the disease. It is more common in women than in men. A family history of cardiovascular disease also increases the risk.

Risk Factors for Pigmentary Glaucoma. Pigmentary glaucoma occurs three times more often in men then in women and at a younger age.

Risk Factors for Irido Corneal Endothelial Syndrome. This condition occurs more often in light-skinned women.