Chicago - Refractive errors (inability of the eye to focus properly) affect about one-third of people 40 years and older in the United States and Western Europe, and one-fifth of Australians 40 or older, according to an article in the April issue of The Archives of Ophthalmology, a theme issue on blindness, and one of the JAMA/Archives journals.
Refractive errors prevent the eyes from focusing correctly and cause blurry vision. Myopia (nearsightedness) and hyperopia (farsightedness) are examples of specific types of refractive errors. Usually, these errors can be easily corrected with glasses, contact lenses or refractive surgery. However, the high prevalence of refractive errors and the costs of correcting these errors make these conditions a substantial public health and economic problem in many parts of the world.
John H. Kempen, M.D., Ph.D., of the Wilmer Eye Institute at The Johns Hopkins Medical Institutions, Baltimore, and a member of The Eye Diseases Prevalence Research Group, and colleagues pooled data from six studies with a combined total of 29,281 participants. The researchers applied the data from the six studies to population data for the year 2000 and projected population data for 2020 from the United States, Western Europe and Australia.
The researchers found the estimated crude prevalence for moderate hyperopia to severe hyperopia was:
- 9.9 percent (11.8 million people) for the United States
- 11.6 percent (21.6 million people) for Western Europe
- 5.8 percent (0.47 million people) for Australia
The estimated prevalence of myopia was:
- 25.4 percent (30.4 million people) for the United States; 4.5 percent of whom (5.3 million people) had more severe forms of myopia
- 26.6 percent (49.6 million people) for Western Europe; 4.6 percent of whom (8.5 million people) had more severe forms
- 16.4 percent (1.3 million people) for Australia; 2.8 percent of whom (0.23 million people) had more severe forms
Projected prevalence rates for 2020 were similar.
Pooled data from the participating population-based eye studies, conducted in persons 40 years or older, indicate that the crude prevalence of myopia is the highest of any eye disorder in this age group, affecting about one in four persons in the United States and Western Europe, and about one in six Australians, the authors write. Approximately one of six persons with myopia one of every 24 persons in the general U.S. and Western European population 40 years or older has myopia of -5 diopters or less [mild to moderate myopia] and may be at risk of pathologic complications of high myopia.
(Arch Ophthalmol. 2004;122:495-505. Available at www.archophthalmol.com.
Editors Note: This study was supported by a contract from the National Eye Institute, Bethesda, Md. Additional support was provided by a grant (Dr. Kempen) from the National Eye Institute. The Eye Diseases Prevalence Research Group is an initiative sponsored by the National Eye Institute of the National Institutes of Health (Bethesda, Md.) with additional funding from Prevent Blindness America (Schaumburg, Ill.) that seeks to estimate the prevalence rates of major eye diseases.