Walking with prisms
Reviewed by Carmel Noonan

This study was undertaken to assess which tempero-spatial properties of gait are influenced by vertical yoked prism (VYP) wear and consider any adjustments to gait made to maintain stability both during and following VYP wear. Thirty-one healthy adults were recruited. Three prism conditions were tested: 5PD base up, 5PD base down, plano. The results showed significant changes in gait patterns while wearing base down prisms with slowed velocity, reduced cadence, shortened step length, increased double support phase and increased step tone variability. These effects were not seen in the base up condition. The only change seen for base up prisms was a narrowed step width. Many reported feeling taller with base down prisms and this could lead to fear of falling and therefore could result in moving with greater caution and hesitancy. Floor perception was of a slanting upwards and away floor with base down prisms and slanting downwards with base up prisms. No difference was seen for measures on repeated assessment after longer term wear apart from a small increase in step length.

The effects of vertical yoked prisms on gait.
Errington JA, Menant JC, Suttle CM, et al.
INVESTIGATIVE OPHTHALMOLOGY AND VISUAL SCIENCE
2013;54:3949-56.