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Incidence and Prevalence
of Sensory Impairments

The estimated population of individuals with deafness and hearing loss in the United States is over 20 million persons. The number of individuals with deafness (defined as an inability to hear any speech) is estimated to be 550,000, and more than half are over the age of 65. Of the 20 million persons with deafness and hearing loss, 4.4% reported congenital hearing loss. Most (33.7%) individuals with hearing loss or deafness report that their hearing loss was due to noise. State and local estimates of the prevalence of hearing loss are not available, in part because the Census Bureau has not included a question about hearing impairment since 1930.

The degree of visual impairment ranges widely in individuals, and four categories of visual impairment currently exist: Partially sighted, low vision, legal blindness, and complete blindness. These terms are typically used in the educational context to describe the needs of children with various levels of visual impairment. "Partially sighted" means that there is some type of visual problem requiring specific education or intervention; "low vision" generally refers to a severe visual impairment, requiring adaptations in lighting, print size, or alternative print formats, such as Braille; "legally blind" refers to the condition of having vision that is less than 20/200 in the better eye with correction or an extremely limited field of vision (an arc of 20 degrees or less); and "complete blindness" indicates that the person requires the use of non-visual media, such as Braille, screen-readers, etc. to receive information. The rate at which visual impairments occur in individuals under the age of 18 is 12.2/1,000. "Legal" and "complete" blindness combined occur at a rate of .06/1,000 for those under age 18. A study of Americans over the age of 40 years found that approximately 937,000 individuals in this demographic were legally blind. Another 2.4 million Americans over 40 had low vision.

Deaf-blindness, also known as dual sensory impairment, is the condition of a combination of sensory impairments sufficient to warrant adaptations and/or assistive technologies to aid communication, beyond those that would be provided for hearing or visual impairment alone. Most individuals with dual sensory impairment have some usable vision and/or hearing. The number of people with dual sensory impairment is estimated to be 40,000 in the United States. The incidence of congenital dual sensory impairment is estimated to be 3/100,000.

Prevalence and causes of visual and hearing impairment vary according to sex, age, racial/ethnic background, and socio-economic status. The number of Americans with visual and/or hearing impairments is expected to rise dramatically over the next 20 years, due to the aging population.

References

Nevada Dual Sensory Impairment Project. Deaf-Blindness. Retrieved January 3, 2006, from http://www.unr.edu/educ/ndsip/factsheets/deafblindness.pdf

The Eye Diseases Prevalence Research Group (2004). Causes and prevalence of visual impairment among adults in the United States. Archives of Ophthalmology, 122, 477-485.

Holt, J., Hotto, S., & Cole, K. (1994). Demographic aspects of hearing impairment: Questions and answers. Center for Assessment and Demographic Studies, Gallaudet University. Retrieved on January 3, 2006 from http://gri.gallaudet.edu/Demographics/factsheet.html