The Effects of Vertical Yoked Prisms on Gait

Abstract

Citation: Errington JA, Menant JC, Suttle CM, Bruce J, Asper LJ. The effects of vertical yoked prisms on gait. Invest Ophthalmol Vis Sci. 2013;54:3949-3956. DOI:10.1167/ iovs.12-10955 PURPOSE. To investigate the influence of base down (BD) and base up (BU) yoked prism wear on gait.METHODS. Gait was assessed in 31 young healthy adults (mean age, 24.0 6 5.1 years) during and after wearing 5 prism diopter ( D ) BU yoked prisms, 5 D BD yoked prisms, and plano (PL) (zero power; control condition) lenses, worn in a pseudorandom order. Velocity; cadence; step length; double support phase; step width; and variability in step time, step width, step length, and swing time were measured as participants walked at a freely chosen walking speed along a 5.3-m electronic mat placed in the center of a 7.5-m walkway. Gait parameters were analyzed for each viewing condition before, during, and after prism wear.RESULTS. BD yoked prisms, when compared with PL, led to slower velocity, lower cadence, decreased step length, and increased step time variability (P 0.001) These gait parameters did not significantly differ between BU yoked prisms and PL lenses (P > 0.05). Measurements taken immediately on removal did not differ from those taken after a time delay of 5 minutes.CONCLUSIONS. BD yoked prisms affected gait in young healthy adults walking across an unobstructed path at their freely chosen walking speed, in that participants adopted a slower, apparently more cautious gait pattern; BU yoked prisms did not significantly affect gait. The effect of BD prism on gait may be due in part to a perception of increased height.

Negligible Impact on Posture From 5-Diopter Vertical Yoked Prisms

“…As discussed earlier, Sheedy and Parsons 13 found a small degree of head extension after 2 weeks of 4-D yoked prism base-down wear, suggesting that yoked prisms might have had a greater effect on head and body posture in the present study if they had been worn for a longer period. In a previous study, 18 we found an effect of 5-D base-down yoked prisms on gait after only 7 minutes, which suggests that an effect on posture would be expected within a short period, but it remains possible that we would see an effect after a longer period of prism wear.…”

“…The participant's task was to stand still for 30 seconds while viewing a cross marked on a wall in the participant's straightahead line of sight, at a distance of 1.40 m. Within each of the three lens conditions, marker coordinates were measured before (PRE, no goggles or lenses; the control condition) lens wear; immediately on lens wear (ON), at 10, 20, and 30 minutes of wearing the lenses; and immediately after lens removal (OFF). A total period of 30 minutes of prism wear was chosen on the basis of previous work 18,19 in which a significant effect of yoked prism was found after short periods.…”

Aplicação De Prismas Gêmeos Em Terapias Optométricas

“…Os indivíduos apresentaram mudanças em sua marcha, diminuindo seus passos e sendo mais cautelosos em sua caminhada quando estavam utilizando os prismas de base inferior, o qual não se apresentou mudança significativa quando eles se encontravam usando os prismas gêmeos de base superior. Se levantou a hipótese de mudança no andar devido a percepção de aumento da altura (Errington et al, 2013).…”

Development of a Reference Spatiotemporal Gait Data Set for Indian Subjects: A Pilot Study

“…Spatiotemporal gait measures were obtained using a BTS Bioengineering GAITLAB©, the setup of which was equipped with six infrared cameras, a force plate measuring kinetic data and a 7.5 meter walkway. [3] A computer was connected to the BTS Bioengineering Smart-DX Engine and ran the BTS Smart Clinic software that comprised an equipment connection diagnostic tool, a capturing tool and a cataloging application where sociodemographic data and anthropometric measures were collected and stored. Axes and wand calibrations were run multiple times to ensure optimal calibration and reliable data.…”