Blindness and Visual Impairment

Blindness is a difficult term to define because it represents a vast range of ability to perceive the outside world (Warren 1994). For example, the term legally blind describes many people, however only 25% of the legally blind see little or no light. Yet, of all the definitions of blindness, legal blindness is perhaps the most agreed upon. This definition encompasses people who, with correction, have a vision of 20/200 or less in their better eye or/and a visual field of less than 20°. While these criteria were developed for purposes of aid distribution, children with the same vision can have vastly different visual experiences. In schools, a visual acuity of 20/60–20/70 is required to receive special education and between 20/60 and 20/200 a child is said to be visually impaired.

Blindness can result from many factors. The most fundamental causes are seen most notably in third-world countries where things such as nutritional deficits, bacteria, and infections cause between one third...