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