Multifocal Spectacles Increase Variability in Toe Clearance and Risk of Tripping in the Elderly

Abstract

Because of increased within-subject variability in vertical toe clearance when wearing multifocal spectacles, elderly individuals may be at greater risk of falling when negotiating steps and stairs if they do not also consistently increase margins of safety (mean vertical toe clearance). This suggests that some elderly who are at high risk of falling may benefit from wearing single-distance vision rather than multifocal spectacles when walking.

The role of tread fixations in the visual control of stair walking

“…However, the data also suggest that foveal information on stair treads was not imperative for safe stair walking, since a substantial 28% (stair descent, two treads a time) to 34% (stair descent, one tread a time) of the treads that was stepped on, was never fixated. While the importance of accurate visual information on the stepping surface has been demonstrated in other studies [1][2][3][4][5][6][7], the present findings suggest that foveal monitoring of future foot landing areas is not a prerequisite for safe foot placement on the staircase. Instead, the online guidance of foot placement may rely on the combined use of foveal and perifoveal sources of visual information.…”

“…Previous studies on stair walking have made clear that both foot placement and balance control depend on vision, and that stair walking under suboptimal visual conditions results in altered balance control [1,2] and changes in foot placement strategies [3][4][5][6][7]. To understand how vision contributes to stair walking, it is important to know which elements in the environment provide the essential visual cues, and how this information is transformed into adequate gait behavior.…”

Altered vision destabilizes gait in older persons

“…This interpretation is in accordance with a study by Marigold and Patla [14] in which reduction of the lower visual field affected footfall parameters in young healthy adults. Similar problems can arise when older persons use multi-focal glasses, which increases fall risk during gait [27].…”

Visual loss and falls: a review

“…Multifocal glasses have also been shown to affect toe clearance and risk of tripping. 60 It may be that impaired distance contrast sensitivity and depth perception through the near portion of multifocal glasses is a mechanism for this effect. 44 Balance relies on the co-ordination of stimuli from the visual and vestibular system, with proprioception, muscle strength and reaction time also contributing.…”