Buckley John G, Heasley Karen, Scally Andy, Elliott David B
Department of Optometry, University Bradford, Richmond Building, West Yorkshire, UK.
Gait Posture. 2005 Oct;22(2):146-53. doi: 10.1016/j.gaitpost.2004.08.006.
Visual impairment is an important risk factor for falls, but relatively little is known about how it affects stair negotiation. The present study determined how medio-lateral (ML) dynamics of stepping and single limb support stability when stepping up or down to a new level were affected by blurring the vision of healthy elderly subjects. Twelve elderly subjects (72.3 +/- 4.2 years) were analysed performing single steps up and single steps down to a new level (7.2, 14.4 and 21.6 cm). Stepping dynamics were assessed by determining the ML ground reaction force (GRF) impulse, lateral position of the centre of mass (CM) relative to the supporting foot (average horizontal ML distance between CM and CP during single support) and movement time. Stability was determined as the rms fluctuation in ML position of the centre of pressure (CP) during single support. Differences between optimal and blurred visual conditions were analysed using a random effects model. Duration of double and single support, and the ML GRF impulse were significantly greater when vision was blurred, while the average CM-CP ML distance and ML stability was reduced. ML stability decreased with increasing step height and was further decreased when stepping down than when stepping up. These findings indicate that ML balance during stepping up and down was significantly affected by blurring vision. In particular, single limb support stability was considerably reduced, especially so during stepping down. The findings highlight the importance of accurate visual feedback in the precise control of stepping dynamics when stepping up or down to a new level, and suggest that correcting common visual problems, such as uncorrected refractive errors and cataract may be an important intervention strategy in improving how the elderly negotiate stairs.
视力障碍是跌倒的一个重要风险因素，但对于它如何影响上下楼梯的过程，人们了解得相对较少。本研究确定了通过模糊健康老年受试者的视力，对上、下到新高度时的跨步中外侧（ML）动力学以及单腿支撑稳定性有何影响。分析了12名老年受试者（72.3±4.2岁）进行上、下到新高度（7.2、14.4和21.6厘米）的单步动作。通过确定ML地面反作用力（GRF）冲量、质心（CM）相对于支撑脚的横向位置（单支撑期间CM与压力中心（CP）之间的平均水平ML距离）和移动时间来评估跨步动力学。稳定性被确定为单支撑期间压力中心（CP）的ML位置的均方根波动。使用随机效应模型分析最佳视觉条件和模糊视觉条件之间的差异。当视力模糊时，双支撑和单支撑的持续时间以及ML GRF冲量显著增加，而平均CM-CP ML距离和ML稳定性降低。ML稳定性随着步高的增加而降低，并且下楼梯时比上楼梯时进一步降低。这些发现表明，上下楼梯时的ML平衡受到视力模糊的显著影响。特别是，单腿支撑稳定性显著降低，尤其是在下楼梯时。这些发现凸显了准确的视觉反馈在精确控制上、下到新高度时的跨步动力学中的重要性，并表明纠正常见的视觉问题，如未矫正的屈光不正和白内障，可能是改善老年人上下楼梯方式的重要干预策略。
