Total blindness is a rare occurrence among the blind population. In fact, a person who is legally blind may still have some usable vision. Rather than a specific eye condition, blindness constitutes a level of visual acuity resulting from any number of visual disorders that affect varying types of vision (such as central or peripheral). Legal blindness is defined in clinical terms as having central visual acuity of 20/200 or less in the better eye with the best possible correction and/or a visual field of 20 degrees or less.