Citation

Foster RJ, Whitaker D, Scally AJ, Buckley JG, Elliott DB. Invest. Ophthalmol. Vis. Sci. 2015; 56(5): 2950-2957.

Affiliation

Bradford School of Optometry and Vision Science, University of Bradford, Bradford, United Kingdom.

Copyright

(Copyright © 2015, Association for Research in Vision and Ophthalmology)

DOI

10.1167/iovs.14-16018

PMID

26024081

Abstract

PURPOSE: Falls on stairs are a significant cause of morbidity and mortality in elderly people. A simple safety strategy to avoid tripping on stairs is increasing foot clearance. We determined whether a horizontal-vertical illusion superimposed onto stairs to create an illusory perceived increase in stair-riser height would increase stair ascent foot clearance in older participants.

METHODS: Preliminary experiments determined the optimum parameters for the horizontal-vertical illusion. Fourteen older adults (mean age ± 1 SD, 68.5 ± 7.4 years) ascended a three-step staircase with the optimized version of the horizontal-vertical illusion (spatial frequency: 12 cycles per stair riser) positioned either on the bottom or top stair only, or on the bottom and top stair simultaneously. These were compared to a control condition, which had a plain stair riser with edge highlighters positioned flush with each stair-tread edge. Foot clearance and measures of postural stability were compared across conditions.

RESULTS: The optimized illusion on the bottom and top stair led to a significant increase in foot clearance over the respective stair edge, compared to the control condition. There were no significant decreases in postural stability.

CONCLUSIONS: An optimized horizontal-vertical visual illusion led to significant increases in foot clearance in older adults when ascending a staircase, but the effects did not destabilize their postural stability. Inclusion of the horizontal-vertical illusion on raised surfaces (e.g., curbs) or the bottom and top stairs of staircases could improve stair ascent safety in older adults.

Language: en