AMD is a disorder of the retina that affects mostly older people and causes gradual vision loss. Cataracts are caused by increasing opacity in the lens of the eye, and glaucoma is damage to the optic nerve caused by elevated pressure in the eye. According to information in the article, blindness and low vision are major causes of impairment among Americans. However, few population-based studies of national scope have been carried out in the United States to estimate the prevalence of visual impairment.
Nathan Congdon, M.D., M.P.H., of the Wilmer Eye Institute at The Johns Hopkins Medical Institutions, Baltimore, and The Eye Diseases Prevalence Research Group, and colleagues estimated the prevalences of various causes of blindness and low vision in the United States by age, race/ethnicity, and gender, and estimated the change in these prevalence figures over the next 20 years. The researchers based their estimates on recent population-based studies in the United States, Australia and Europe, and applied these estimates to 2000 U.S. Census data and to projected U.S. population figures for 2020 to determine the number of Americans with visual impairment.
The researchers found that an estimated 937,000 (0.78 percent) Americans older than 40 were blind. An additional 2.4 million Americans (1.98 percent) had low vision. "The leading cause of blindness among white persons was age-related macular degeneration (54.4 percent of the cases), while among black persons, cataract and glaucoma accounted for more than 60 percent of blindness," the authors write. Cataracts were the leading cause of low vision. Among Hispanics,
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