Main Menu Age Related Macular Degeneration Cataract Diabetic Retinopathy Glaucoma Vision Impairment and Blindness Eye Diagram Glossary   Our Other Sites Bookstore Directory Other Resources Vision Health Resources Vision Loss and Blindness Resources Search All Sites Site Map Refractive Error Refractive errors are the most frequent eye problems in the United States. They are optical defects that result in light not being properly focused on the eye's retina. Nearsightedness (myopia) and farsightedness (hyperopia) are the most common refractive errors. People with myopia see near objects clearly, while distant ones are blurred. People with hyperopia experience just the opposite ­- distant objects are clear while near ones are blurred. Why refractive errors develop is uncertain. Most infants have some degree of hyperopia, but vision becomes more normal with age, usually leveling off by age 6. However, some children remain farsighted or become so later in life. While some children may be nearsighted early in life, most myopia occurs later during adolescence. Refractive error can continue to change over our lifetime. Other common refractive errors include astigmatism (uneven focus) and presbyopia (age-related problem with near focus). Fortunately, almost all refractive errors can be corrected by eyeglasses or contact lenses. It is estimated that more than 150 million Americans use corrective eyewear to compensate for their refractive error. Americans are estimated to spend over $15 billion each year on eyewear, supporting an optical industry in the U.S. worth more than $30 billion. Refractive surgery is now another alternative for correcting problems such as myopia, hyperopia and astigmatism. The number of people seeking refractive surgery is increasing. However, the surgical procedures are not without some risk and the long-term effects of many of these procedures are still unknown. Uncorrected or under-corrected refractive error can result in significant vision impairment. The magnitude of refractive error is measured in units called diopters. For each diopter of refractive error, a person may be unable to read the next smaller line of an eye chart. For instance, a person with more than two diopters of hyperopia might find it difficult to read this text. Cases of refractive error described in the following charts include myopia of 1.0 diopters or more. The threshold for clinically significant hyperopia is somewhat higher at 3.0 diopters or more. Myopia is a very common disorder affecting more than 30.5 million Americans age 40 and older. Prevalence is greater in women through age 60 when rates become more comparable between genders (see chart below). Myopia affects more Whites than other races, and is generally less frequent with age. Because of the higher threshold for significance, hyperopia is less common, affecting 12 million older Americans. Prevalence of hyperopia generally increases with age (see chart below). It is most frequent in Whites, but also affects Hispanics more often than Blacks. Available tables for Hyperopia: Estimated Number of Cases of Hyperopia (3.00 diopters or worse) in the U.S. Population Aged 40 and over by State, Race and Sex Prevalence Rates for Hyperopia (3.00 diopters or worse) by State, Race and Sex National age-specific prevalence rates for hyperopia (3.00 diopters or worse) U.S. Census 2000 Population aged 40 and over by Race and Sex The tables are located on the following page: Estimated number of cases of hyperopia Available tables for Myopia: Estimated Number of Cases of Myopia (-1.00 diopters or worse) in the U.S. Population Aged 40 and over by State, Race and Sex Prevalence Rates for Myopia (-1.00 diopters or worse) by State, Race and Sex National age-specific prevalence rates for myopia (-1.00 diopters or worse) U.S. Census 2000 Population aged 40 and over by Race and Sex The tables are located on the following page: Estimated number of cases of myopia Notes: Each page opens in a new window. There are 4 tabs located in the bottom left corner that select the different tables. All brands and product names are trademarked or registered trademarks of their respective companies. Copyright of syndicated content belongs to it’s respective author or news organization. Original content (including "look and feel") Copyright © 2001-2006  •  Vision Loss and Blindness Resources  •  All rights reserved.