Blindness Education

Blindness, complete or almost complete absence of the sense of sight. It may be caused by any obstacle to the rays of light on their way to the optic nerve, or by disease of the optic nerve or tract, or of that part of the brain connected with vision. It may be permanent or transient, complete or partial, or in effect only in low-light conditions (night blindness). The World Health Organization defines “profound blindness” as the inability to count fingers at a distance of 3 m (10 ft) or less. Visual defects are one of the most common causes of disability in the world.

Different eye conditions create different problems. Very few blind people see nothing at all; a minority can distinguish light from dark but nothing else; the majority possess varying degrees of useful vision. Some have no central vision; others have no side vision. Some see everything as a vague blur; others see a patchwork of blank and defined areas. Some see best in sunlight, others prefer twilight. All this means that no two blind people see the world in the same way, so some blind people can see enough to read this encyclopedia, though they might have difficulty crossing the road.

The first printing in raised letters on paper was introduced by Haüy in 1784. He used the italic style of type, embossing the paper with large and small letters set in movable type by his pupils; other styles of type were tried later. Because of the large size of type required, however, the books produced were bulky and expensive. The only system of line type (type characters consisting of embossed lines) in current use is based on outlines of the roman letters; it was invented by William Moon in England in 1847.

In 1821 a French army captain, Charles Barbier, invented a system of point type, a code based on groups of dots. Louis Braille adapted Barbier’s system, using groups of one to six dots. A conference of workers for blind people held in London in 1932 to standardize point systems adopted an alphabet known as Standard English Braille, which is the original Braille alphabet with a few modifications. The Braille system is now used throughout the English-speaking world and has been adapted to most other languages, including Chinese. Braille also devised a system of point characters for musical notation.

Among the early appliances to aid blind people in writing was the grooved tablet, a sheet of metal or board grooved in small squares. The paper was placed on the tablet, and the pencil, guided by the grooves, indented the paper, forming a large, square handwriting that could be distinguished by both sight and touch. Modern methods include the use of the typewriter for correspondence with people who can see and the use of tablets for guiding the writer in the formation of Braille characters. In addition, the Hall Braille writer, a modification of the typewriter, embosses Braille characters on the paper instead of printing visible letters.

Deaf blind people, with or without the ability to speak, have other special needs; their rehabilitation usually requires home teachers.