Psychological correlates of walking speed in the visually impaired.

Recent attempts to extend mobility evaluation techniques to include the partially sighted as well as the totally blind have demanded the development of new measures. One of these, the percentage of preferred walking speed (PPWS) reflects the slower walking speed of visually impaired pedestrians. This reduction in speed may be due either to the impoverished visual information available for the control of locomotion, or it may be due to a strategic response to the stress associated with travel. Using a client-derived mood checklist, this latter hypothesis was confirmed. In contrast, visual status, as measured by both acuity and field loss, was unrelated to PPWS. This mobility index is an important addition to existing measures, which are concerned with safety, efficiency and visual function.