Demographics of Vision Loss in the United States: Dealing with Definitions

Abstract

Reporting demographic characteristics about people with vision loss is challenging because inconsistent measuring criteria or varying definitions are used by different surveys that collect demographic data to identify people with vision loss. The resulting information varies widely, just as does the terminology the surveys use to identify people with visual impairments. For example, commonly used terms to identify people with vision loss include legal blindness, total blindness, blindness, visual impairment, low vision, functional limitation in seeing, and severe limitation in seeing. Within these terms there are also degrees of vision loss that can affect how surveys identify visually impaired people. DEFINITIONS DETERMINE EVERYTHING Because there is not one definitive statistic from a single source that accounts for everyone with vision loss in the United States, it is important that those seeking information about vision loss, as well as those providing answers, first understand that there are several definitions of vision loss to choose from among the various national household surveys. Whenever questions about demographic statistics about people with visual impairment or blindness come to the American Foundation for the Blind (AFB), the first step in answering such questions is to understand precisely which group of visually impaired people the questioner is interested in. The answer to this question determines whether the response offers statistics on the number of people with blindness, severe visual impairment, or low vision. The surveys that track people with vision loss in the United States define visual impairment in the following ways. The most recent National Health Interview Survey (NHIS), published in 2008, defines individuals with vision loss as those who reported that they have trouble seeing, even when wearing eyeglasses or contact lenses. Included in this broad definition are individuals who reported that they are blind or unable to see at all, and no visual acuity cutoff is provided. The 1994-1995 National Health Interview Survey on Disability (NHIS-D) defines individuals who are legally blind as those who reported that they have a central visual acuity of 20/200 or less in the better eye with the best possible correction or a visual field of 20 degrees or less. The definition used by NHIS-D is unique, because there has not been another national survey that explicitly assessed the number of Americans who are legally blind since NHIS-D was conducted in the mid-1990s. …