Myopes Show Greater Visually Induced Postural Responses Than Emmetropes

PURPOSE. The literature already establishes that vision plays a crucial role in postural control and that this visual dependence shows intra- and interindividual variability. However, does ametropia also have an effect on postural control? This question leads to our study, which aims primarily to determine if myopes and emmetropes behave differently in terms of postural control when subjected to visual stimulation, and secondarily, if this difference persists in the presence of barrel and pincushion distortions. The results could lead, among other things, to improved lens design. METHODS. Twenty-four subjects (12 myopes of -2.00 to -9.00 diopters [D] and 12 emmetropes of -0.50 to +0.50 D), between 19 and 35 years of age, participated in the study after comprehensive eye examinations were carried out. Of the 12 myopes, the preferred type of correction was divided equally within the group. While standing in front of a projection system and fixating on an immobile point, a checkerboard stimulus was displayed in their peripheral visual field, in either a static or dynamic state. Three conditions of optical distortion (plan, pincushion, and barrel distortions) were presented to the subjects. Their postural response was measured and recorded using a system of infrared cameras and optical sensors positioned on a helmet. RESULTS. The results show that postural instability induced by a dynamic peripheral stimulus is higher for myopes compared with emmetropes (ANOVA Refractive Error, F-1,F-22 = 5.92, P = 0.0235). When exposed to optical distortions, the two groups also have significant differences in postural behaviors (ANOVA Refractive Error* Optical Distortion, F-2,F-44 = 5.67, P = 0.0064). CONCLUSIONS. These results suggest that refractive error could be a factor in explaining individual variations of the role of vision in postural control.