Citation

Timmis MA, Johnson L, Elliott DB, Buckley JG. Invest. Ophthalmol. Vis. Sci. 2010; 51(8): 3903-3908.

Affiliation

Division of Medical Engineering, School of Engineering Design & Technology, University of Bradford, Bradford, United Kingdom.

Copyright

(Copyright © 2010, Association for Research in Vision and Ophthalmology)

DOI

10.1167/iovs.09-4987

PMID

20207976

Abstract

Purpose: Epidemiological research has shown that multifocal spectacle wearers (bifocal and progressive addition lenses, PALs) are more than twice as likely to fall compared with non-multifocal spectacle wearers with this risk further increasing when negotiating stairs. The present study investigated whether step/stair descent safety is improved by using single-vision distance lenses. Methods: From a stationary standing position on top of a block, twenty long-term multifocal wearers stepped down (from different block heights) onto a lower level wearing either bifocal, PALs or single-vision distance lenses. Results: Use of single-vision distance spectacles lead to an increased single-limb support time, a reduced ankle and knee angle and vertical centre-of-mass velocity at contact with the lower level, and a reduced ankle angular velocity and vertical centre-of-mass velocity during initial landing (p < 0.03). These findings indicate that landing occurred in a more controlled manner when wearing single-vision distance spectacles, rather than tending to 'drop' onto the lower level as occurred when wearing bifocals or PALs. Conclusion: Use of single-vision distance spectacles lead to improvements in landing control, consistent with individuals being more certain regarding the precise height of the lower floor level. This was attributed to having a view of the foot, step edge and immediate floor area that was not blurred, magnified or doubled and that did not suffer from image jump or peripheral distortions. These findings provide further evidence that use of single-vision distance lenses in everyday locomotion may be advantageous for elderly multifocal wearers who have a high risk of falling.

Language: en