Information AboutBlindness |
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Blindness is the condition of lacking Visual Perception due to Physiological or Psychological factors. Various scales have been developed to describe the extent of vision. Those described as having only "light perception" can see no more than the ability to tell light from dark. A person with only "light projection" can tell the general direction of a light source. In order to determine which people may need special assistance because of their visual disabilities, various governmental jurisdictions have formulated more complex definitions referred to as legal blindness.Belote, Larry. "Low Vision Education and Training: Defining the Boundaries of Low Vision Patients." ''A Personal Guide to the VA Visual Impairment Services Program.'' Retrieved March 31, 2006. In North America and most of Europe , legal blindness is defined as Visual Acuity (vision) of 20/200 (6/60) or less in the better eye with best correction possible. This means that a legally blind individual would have to stand 20 feet (6 m) from an object to see it with the same degree of clarity as a normally sighted person could from 200 feet (60 m). In many areas, people with average acuity who nonetheless have a Visual Field of less than 20 Degree s (the norm being 180 degrees) are also classified as being legally blind. Approximately ten percent of those deemed legally blind, by any measure, have no vision. The rest have some vision, from light perception alone to relatively good acuity. Low Vision is sometimes used to describe visual acuities from 20/70 to 20/200. {Link without Title} By the 10th Revision of the WHO International Statistical Classification of Diseases, Injuries and Causes of Death, ''low vision'' is defined as visual acuity of less than 6/18, but equal to or better than 3/60, or corresponding visual field loss to less than 20 degrees, in the better eye with best possible correction. ''Blindness'' is defined as visual acuity of less than 3/60, or corresponding visual field loss to less than 10 degrees, in the better eye with best possible correction. {Link without Title} {Link without Title}
LEGAL BLINDNESS In 1934, the American Medical Association adopted the following definition of blindness: "Central visual acuity of 20/200 or less in the better eye with corrective glasses or central visual acuity of more than 20/200 if there is a visual field defect in which the peripheral field is contracted to such an extent that the widest diameter of the visual field subtends an angular distance no greater than 20 degrees in the better eye." The program {Link without Title} which currently states: "An individual shall be considered to be blind for purposes of this title if he has central visual acuity of 20/200 or less in the better eye with the use of a correcting lens. An eye which is accompanied by a limitation in the fields of vision such that the widest diameter of the visual field subtends an angle no greater than 20 degrees shall be considered for purposes of the first sentence of this subsection as having a central visual acuity of 20/200 or less. An individual shall also be considered to be blind for purposes of this title if he is blind as defined under a State plan approved under title X or XVI as in effect for October 1972 and received aid under such plan (on the basis of blindness) for December 1973, so long as he is continuously blind as so defined." Kuwait is one of many nations that share the same criteria for legal blindnessAl-Merjan JI, Pandova MG, Al-Ghanim M, Al-Wayel A, Al-Mutairi S. "Registered blindness and low vision in Kuwait." ''Ophthalmic Epidemiol.'' 2005 Aug;12(4):251-7. PMID 16033746.. Epidemiology In 1987, it was estimated that 598,000 people in the United States met the legal definition of blindnessKirchner, C., Stephen, G. & Chandu, F. (1987). "Estimated 1987 prevalence of non-institutionalized 'severe visual impairment' by age base on 1977 estimated rates: U. S.", 1987. ''AER Yearbook.''. Of this number, 58% were over the age of 65. In 1994-1995, 1.3 million Americans reported legal blindnessAmerican Foundation for the Blind. "Statistics and Sources for Professionals." Retrieved April 1, 2006.. |
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