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dc.contributor.authorHeasley, Karen*
dc.contributor.authorBuckley, John*
dc.contributor.authorScally, Andy J.*
dc.contributor.authorTwigg, Peter C.*
dc.contributor.authorElliott, David B.*
dc.date.accessioned2014-07-18T16:29:52Z
dc.date.available2014-07-18T16:29:52Z
dc.date.issued2004
dc.identifier.citationHeasley K, Buckley JG, Scally AJ, Twigg P and Elliott DB (2004) Stepping up to a new level: effects of blurring vision in the elderly. Investigative Ophthalmology and Visual Science. 45(7): 2122-2128.en_US
dc.identifier.urihttp://hdl.handle.net/10454/6406
dc.description.abstractPURPOSE. To determine the effects of blurring vision on whole-body center-of-mass (CM) dynamics and foot-clearance parameters in elderly individuals performing a single step up to a new level. METHODS. Twelve healthy subjects (mean age, 72.3 ±4.17 years) performed a single step up to a new level (heights of 73 and 146 mm). Trials were undertaken with vision optimally corrected and with vision diffusively blurred by light-scattering lenses (cataract simulation). CM and foot-clearance parameter data were assessed by analyzing data collected by a five-camera, three-dimensional (3-D) motion analysis system. RESULTS. When vision was blurred, subjects took 11% longer to execute the stepping task (P < 0.05), mediolateral displacement of the point of application of the ground reaction force vector (i.e., weighted average of all pressures over the area in contact with the ground; the so called center of pressure, CP) decreased from 37.6% of stance width to 28.3% (P < 0.01), maximum distance between the mediolateral position of the CM and CP decreased by 9.8 mm (P < 0.01), and toe clearance (distance between tip of shoe and edge of step) increased in both the horizontal (28%) and vertical (19%) direction (P < 0.05). CONCLUSIONS. These findings suggest that when vision was blurred, subjects used a twofold safety-driven adaptation: First, to increase dynamic stability they ensured that the horizontal position of their CM was kept close to the center of the base of support and second, they increased horizontal and vertical toe clearance while swinging their lead limb forward to reduce the risk of tripping.en_US
dc.language.isoenen_US
dc.subjectBlurring vision; Elderly; Center-of-mass (CM); Dynamics; Foot-clearance parameters; Stepping; Dynamic stability; Toe clearance; Trippingen_US
dc.titleStepping up to a new level: effects of blurring vision in the elderlyen_US
dc.status.refereedn/aen_US
dc.typeArticleen_US
dc.type.versionNo full-text available in the repositoryen_US
dc.identifier.doihttps://doi.org/10.1167/iovs.03-1199


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