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Relationship between central and peripheral visual tendencies and center of balance responses to yoked prism

1 May 1994


Peripheral vision has been shown to help stabilize subjects on a balance task more than central vision. Lenses and prisms have been shown to affect a person's center of balance. A study by Jeske demonstrated significant shifts in center of balance upon the application of yoked prism. The question posed by this study is, " do subjects who tend to pay more attention to peripheral visual information respond differently to 12 prism diopters of vertically yoked prism than do those subjects who pay more attention to central visual information?" Replication of the results found by Jeske was also attempted. Subjects were 25 non-optometry students. The subject's tendency to pay attention to peripheral or central visual information was measured using a combination of the scores on a distance maddox rod phoria, peripheral visual response speed as measured by the Wayne Peripheral Awareness Tester and Trainer, and score on the rod and frame apparatus. The subject's center of balance response to vertically yoked prism was measured using the BALANCE SYSTEM: from the Chattecx corporation. It consists of a computerized balance platform from which footplates take rapid samples of percent of body weight shift based on an X-Y coordinate system. The X values quantified leftward or rightward center of balance position (X COB). The Y values quantified the forward or rearward center of balance positions (YCOB). Postural sway, dispersion, was also measured (PS). No significant differences were found between the prism conditions in the XCOB or PS analysis. Significant differences were seen in the YCOB variable when the base-down yoked prism condition was compared to the base'"UP prism condition. The central or peripheral processing characteristics did not show a significant relationship to YCOB response to yoked prism. Effects of refractive error and habitual standing posture on YCOB response to yoked prism was also measured. The myopes and the emmetropes responded significantly (p < 0.05) more to the base-up prism than did the hyperopes, and the hyperopes and emmetropes responded signiticantly (p < 0.05) more to the base-down yoked prism. Signiticant differences (p < 0.05) between subjects with a forward habitual posture and those with a rearward habitual posture were found for the base-down and baseup conditions, as well as the post base-up condition. Jeske's study was only partially replicated. The center versus peripheral processing characteristics are not predictors of an individual's response to yoked prism. Better predictors of center of balance response to yoked prism are refractive error and habitual standing posture.


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