The development or re-establishment of movement in patients with abnormal vision

It is a most surprising fact that the study of movement in relation to vision has almost totally evaded scientific investigation up to a few years ago. As I stated in 1964, the problem presented itself to me as soon as I entered a school for the blind. Why, if blindness was their only handicap did these children present such a picture of physical abnormality, poor posture, awkward gait and a vast range of neurological symptoms reminiscent of almost every disease of the nervous system? In 1966, Dr. Irwin Siegel, consultant orthopaedist to the Chicago Institute for the Visually Handicapped wrote, "Two years ago I blindfolded myself and took a step-as an orthopaedist I had treated many posture problems, but always in sighted patients. The blindfold changed this, for with one step I entered a world where posture, balance and mobility were not governed by sight." If not by sight, then by what?