Blindness and Visual Impairment

Definitions of Blindness and Visual Impairment

The World Health Organization's (WHO) International Statistical Classification of Diseases and Related Health Problems (ICD-10) defines blindness as visual acuity of “less than 3/60 (0.05) or corresponding visual field loss in the better eye with best possible correction” (visual impairment categories 3, 4, and 5 in ICD-10). This corresponds to loss of walkabout vision. “Low vision is classified as visual acuity of less than 6/18 (0.3) but equal to or better than 3/60 (0.05) in the better eye with the best possible correction” (visual impairment categories 1 and 2 in ICD-10). The international medical community generally accepts the ICD definitions of disease and uses it to describe and diagnose medical conditions, diseases, and disabilities.

Almost all U.S. government agencies have adopted medical measurements broken down into three categories of visual impairment, which are used to determine eligibility for services and financial compensation:

• 1.
  Totally blind
• 2.
  Legally blind (20/200 or less visual acuity in the best corrected eye [20/200 visual acuity means that what a fully sighted person sees from 200 feet away, a person with 20/200 vision sees from 20 feet away], and/or 20 degrees or less in the visual field)
• 3.
  Partially sighted (20/70 visual acuity in the bestcorrected eye or 20 degrees or less in the visual field); the U.S. Bureau of the Census simplifies its definition into lay terms (unable to see regularsize newsprint)

All of these definitions of blindness and visual impairment determine eligibility for financial support, social services, and government-funded medical services, including research studies, treatment, cure, ocular prosthetics, rehabilitation training, and job placement. Given these governmental definitions of blindness, it is commonly assumed (particularly by sighted people) that someone would only identify as “blind” if they had no vision at all. However, many people categorized as “legally blind” actually identify as blind. These people challenge traditional notions of blindness because they retain some usable vision, demonstrating that blindness, like sight, is a continuum. Many people identified as “legally blind” or “partially sighted” greatly benefit from standard accommodations for blindness, such as audio description of environments, access devices and technology, books on audiotape or compact disk, and universal design.

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