Definitions of Blindness

The term "legally blind" refers to people who are partially sighted as well as those who are totally blind. Eighty-five percent or more of the legally blind population has some vision; those remaining are totally blind, "seeing" nothing but darkness.

Legal blindness can be defined in two ways:

Visual acuity of 20/200 or less with the best possible correction. Visual acuity is defined as the ability to distinguish object detail and shape.
A visual field of 20 degrees of less in the better eye. Visual field is defined as the extent of space visible as the eye looks straight ahead.