<P> Others read Braille (or the infrequently used Moon type), or rely on talking books and readers or reading machines, which convert printed text to speech or Braille . They use computers with special hardware such as scanners and refreshable Braille displays as well as software written specifically for the blind, such as optical character recognition applications and screen readers . </P> <P> Some people access these materials through agencies for the blind, such as the National Library Service for the Blind and Physically Handicapped in the United States, the National Library for the Blind or the RNIB in the United Kingdom . </P> <P> Closed - circuit televisions, equipment that enlarges and contrasts textual items, are a more high - tech alternative to traditional magnification devices . </P> <P> There are also over 100 radio reading services throughout the world that provide people with vision impairments with readings from periodicals over the radio . The International Association of Audio Information Services provides links to all of these organizations . </P>

Legal blindness in the united states is defined as severe or profound impairment in both eyes