Sommer, Alfred International Center for Epidemiology and Preventive Ophthalmology, Dana Center, Wilmer Institute, Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland.
Last reviewed:January 2019
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Abnormal visual acuity. The term visual impairment is used to describe visual acuity substantially less than normal. The World Health Organization defines visual impairment as acuity less than 20/60 (normal being 20/20). Most states in the United States, however, will not issue an unrestricted driver's license to persons having corrected vision less than 20/40; such persons generally require special aids to read fine print and to perform other visually demanding tasks. The legal definition of blindness (see illustration) in the United States is visual acuity of 20/200 or worse (or severely restricted peripheral vision). The World Health Organization defines blindness as visual acuity worse than 20/400. See also: Eye disorders; Vision
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