Wikipedia Precis

This revision: 9th May 2013 .
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Blindness is the condition of lacking visual perception due to physiological or neurological factors.

Various scales have been developed to describe the extent of vision loss and define blindness.[1] Total blindness is the complete lack of form and visual light perception and is clinically recorded as NLP, an abbreviation for "no light perception."[1] Blindness is frequently used to describe severe visual impairment with residual vision. Those described as having only light perception have no more sight than the ability to tell light from dark and the general direction of a light source.

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 20/60 (6/18), but equal to or better than 20/200 (6/60), 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 20/400 (6/120), or corresponding visual field loss to less than 10 degrees, in the better eye with best possible correction.[4][5]


In a study of 228 visually impaired children in metropolitan Atlanta between 1991 and 1993, 154 (68%) had an additional disability besides visual impairment.[15]


The WHO estimates that in 2002 there were 161 million visually impaired people in the world (about 2.6% of the total population).

Of this number 124 million (about 2%) had low vision and 37 million (about 0.6%) were blind.[26] In order of frequency the leading causes were cataract, uncorrected refractive errors (near sighted, far sighted, or an astigmatism), glaucoma, and age-related macular degeneration.[27]

In 1987, it was estimated that 598,000 people in the United States met the legal definition of blindness.[28] Of this number, 58% were over the age of 65.[28] In 1994-1995, 1.3 million Americans reported legal blindness.[29]

Useful Links

Perkins Learning

Fantastic practical ideas for sensory support and teaching

National Blind Childrens Society

The National Blind Children's Society's objective is to enable blind and partially sighted children and young people to achieve their educational and recreational goals.


The RNIB is the largest UK charity for the blind and partially sighted. They provide an extensive website concerned with visual impairment and blindness for all ages.


The Royal National College for the blind is an beacon FE college for the visually impaired.


Support for parents of visually impaired children


Association for Education and Rehabilitation of the Blind and Visually Impaired


The National Federation of the Blind is the largest US support organisation for the visually impaired

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