A person is considered LEGALLY blind when the best corrected visual acuity is 20/200, or the person's visual field is 20 degrees or less. It is not true that all blind persons have absolutely no sight; in fact, most blind persons have some remaining vision. A person may be considered blind when he/she can no longer drive safely, has difficulty reading a newspaper, or cannot see objects to the side.
Key Definitions of Statistical Terms - American Foundation for the Blind