Cataracts are the leading cause of blindness worldwide, but they can be “cured” with cataract surgery. However, a leading cause of irreversible blindness is glaucoma, and it is a significant public health problem because it is estimated that half of all people who have glaucoma do not know that they have it. This is because the most common form, open-angle glaucoma, has no symptoms, and is thus often called the “silent thief of sight.”
Primary open-angle glaucoma is estimated to affect 2 to 3 percent of the population in the United States in adults ages 40 and older, and the prevalence is estimated to increase as the population overall skews more towards people in older age groups. More than 3 million Americans age 40 and older have glaucoma, with an estimated 2.72 million have open-angle glaucoma, the most common form of this disease1. It has been estimated that in the United States there will be more than 4 million people over the age of 40 with glaucoma by the year 2030, and will increase to more than 6 million people in this same age group by the year 20502. View our glaucoma infographic.
The Leading Cause of Blindness in African Americans
Based on data analyzed in 2012, more than 520,000 of Americans with open-angle glaucoma are African-American. Indeed, open-angle glaucoma is the leading cause of irreversible blindness in African Americans. One of the landmark studies to examine the prevalence of open-angle glaucoma in the African-American community was the Baltimore Eye Survey3, for which the results were published in 1991. This study showed that the prevalence of glaucoma was 4 percent in African Americans ages 50-59, and increased to approximately 13 percent in African Americans ages 80-89. Adjusting for age, African-Americans were 3 to 4 times more likely to have a diagnosis of glaucoma compared to Caucasians. And not only was the overall prevalence higher in African Americans, but the disease began at an earlier age. This study also showed that half of all patients, regardless of ethnicity, were unaware that they had glaucoma.
Why are African Americans at Increased Risk?
Why are African Americans more susceptible to open-angle glaucoma compared to Non-Hispanic Whites? The reasons for this are unclear, although some experts believe it may be related to genetic differences, such as those that lead to differences in the anatomic structure of the optic nerve. More recently, the ADAGES study (African Descent And Glaucoma Evaluation Study)4 was designed to examine the vision and optic nerve structure of Americans of African ancestry versus of those of European ancestry. At the time of the study, more advanced optic nerve imaging techniques were used to examine the optic nerve structure. The study found that there were differences in optic nerve structure between these two groups, including a larger optic nerve area in healthy eyes in people of African descent. The larger size of the nerve can sometimes confuse the diagnosis of glaucoma, since larger nerves can give a false impression of glaucoma.
Overall, in the African American population, open-angle glaucoma is more common, more difficult to treat, and more severe at the time of diagnosis, which results in more blindness.
Glaucoma Risk in Hispanics
Hispanics are another ethnic group that show increased risk of open-angle glaucoma. The Los Angeles Latino Eye Study (LALES)5 was designed to study the prevalence of eye diseases in Latinos, with most of the patients in this study being of Mexican ancestry. The prevalence of open-angle glaucoma in Latinos (approximately 5 percent) was found to be similar to those of African Americans. In this study, 75 percent of Latinos with glaucoma were previously undiagnosed, which may be attributed the large percentage of patients who did not have health insurance. The LALES study also supported findings from other studies that suggest that blood pressure is very important in patients with glaucoma. Patients with very high blood pressure have higher eye pressure, which is known to be a major risk factor in open-angle glaucoma. On the other hand, patients with very low blood pressure also have increased risk of open-angle glaucoma, which is thought to be related to poor blood flow to the optic nerve.
In another recent study6, it was estimated that of the more than 2.7 million people with open-angle glaucoma in the United States, the highest number are people aged 70 to 79 years, women, and non-Hispanic whites. However, by 2050, they estimated that more than 7.3 million people will have open-angle glaucoma, with the highest number still among people ages 70 to 79 years and women, but there will be a shift to Hispanics. Notably, this study predicted that the largest demographic group with glaucoma will be Hispanic men.
Decreasing Your Risk
So what should you do? The best defense against blindness related to glaucoma is having a comprehensive, dilated eye exam. Since glaucoma is age-related, and the diagnosis is often made over a period of time as the eye doctor monitors you, it is worth having a baseline examination by age 40. It is also important to consider whether you have other risk factors for open-angle glaucoma, including increasing age over 40, high eye pressures, a family history of glaucoma, very high or very low blood pressures, extreme nearsightedness, or diabetes. If you have one or more of these risk factors, a comprehensive eye exam including pupil dilation is advisable.
This content was last updated on: July 11, 2018
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