The findings, published in the April issue of the journal Ophthalmology, showed the prevalence of blindness among U.S. Hispanics to be 0.3 percent. This figure is somewhat high for developed countries, the researchers note. In Africa, for example, 1 percent of the population is blind (in Tanzania, 5 percent). Open-angle glaucoma was the most common cause of blindness in Hispanics. Cataract, age-related macular degeneration and diabetic retinopathy also were common.
Hispanics comprise 12 percent of the U.S. population and are the fastest growing ethnic minority in the country, the studies note. It is projected that the number of Hispanics age 55 and older will more than double from 3.5 million in 2000 to 11.4 million in 2025.
Cataract was the most common cause of visual impairment, accounting for 47 percent of all problems. Age-related macular degeneration and diabetic retinopathy accounted for 14 percent and 13 percent of problems, respectively. Open-angle glaucoma was the fourth most common cause, affecting women exclusively.
An earlier study, published in the March issue of the journal Investigative Ophthalmology & Visual Science, found that nearly 75 percent of decreased vision among Hispanics could be corrected by prescription eyeglasses.
"Clearly, getting access to vision care is a real problem for this community," says Sheila K. West, Ph.D., principal investigator of both studies and professor of ophthalmology at Hopkins' Wilmer Eye Institute. "The population we studied, in Arizona, was largely low income and had no access to health insurance, and we believe the same barriers to care exist in many other areas across the country. We must increase vision screening and access to health care services for them."
Adds Beatriz Munoz, M.S., study author and associate professor of ophthalmology, "Education programs and interventions to improve access to eye care could significantly decrease the burden of visual loss among Mexican-Americans. Routine eye examinations are essential to identify people with early eye disease that can be treated before it worsens or causes blindness."
For their studies, researchers evaluated data from their Proyecto VER (Vision Evaluation and Research) study, supported by the National Eye Institute, which looked at vision problems among 4,774 Mexican-Americans ages 40 and older living in Tucson and Nogales, Ariz. Participants were randomly selected based on information from the 1990 census. They filled out a health questionnaire and underwent a thorough eye exam in a clinic.
Sixty-five percent of the participants were born in Mexico, and more than 90 percent had at least one parent also born in Mexico. Overall, they scored poorly on scales designed to assess their adjustment to American culture. Only 35 percent of them completed high school and 66 percent reported an average annual income of less than $20,000.
In the first study, of causes of blindness, the blindness prevalence in those ages 40 to 64 was 0.12 percent, rising to 0.77 percent among those age 65 and older. Visual impairment rates also were age-dependent, increasing from 0.55 percent in those ages 40 to 64 to 5.62 percent in those age 65 and older. Overall, women were more likely than men to have vision loss.
In the younger age category (40-64), diabetic retinopathy was the leading cause of visual impairment, with a prevalence of 0.20 percent. Among people age 65 and older, cataract was the leading cause of visual impairment, with a prevalence of 3 percent, followed by age-related macular degeneration (0.92 percent) and glaucoma (0.46 percent).
In the second study, of uncorrected visual impairment, 8 percent of study participants had visual acuity worse than 20/40. The prevalence of uncorrected vision increased with age from 3 percent in the 40- to 49-year-old group, to 34 percent in the group age 80 and up. Overall, those least likely to have their vision corrected by eyeglasses were older, had less than 13 years of education, were less adjusted to American culture, lacked insurance coverage and had not seen an eye care provider within the past two years.
Those with uncorrected problems were more likely to report difficulties with general vision, near vision, distance vision and driving. These people also were more likely to report difficulties performing tasks, dependency on others, impeded social functioning and impaired mental health.
Other study authors were Rosario Sanchez, M.D., M.P.H.; Aimee Broman, M.A.; and Harry Quigley, M.D., of Hopkins; Jorge Rodriguez, M.D., M.P.H., and Robert W. Snyder, M.D., Ph.D., of the University of Arizona, Tucson; and Ronald Klein, M.D., of the University of Wisconsin, Madison. Rodriguez was at Hopkins when the research was completed.
Rodriguez, J. et al, "Causes of Blindness and Visual Impairment in a Population-based Sample of U.S. Hispanics," Ophthalmology, April 2002, Vol. 109, No. 4: pp. 737-743.
Munoz, B. et al, "Blindness, Visual Impairment and the Problem of Uncorrected Refractive Error in a Mexican-American Population: Proyecto VER," Investigative Ophthalmology & Visual Science, March 2002, Vol. 43, No. 3: pp. 608-614.
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The Wilmer Eye Institute at Johns Hopkins
http://www.wilmer.jhu.edu
National Eye Institute
http://www.nei.nih.gov
American Academy of Ophthalmology
http://www.aao.org
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