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Matthew A. Timmis, Daryl Tabrett, Mike Parker, Kez Latham, Shahina Pardhan; Adaptations In Obstacle Negotiation Among Patients With Central Visual Impairment: Indications Of A Cautious Stepping Strategy. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3149.
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Vision is a significant predictor of falls in the elderly, most commonly occurring during step/stair and obstacle negotiation. The risk of falling is significantly higher among visually impaired individuals compared to normal vision adults of a similar age. To date, there has been no detailed analysis assessing whether differences exist in stepping strategy among patients with central visual impairment and normal vision when required to negotiate an obstacle during ongoing gait.
Following strict inclusion criteria pertaining to ocular comorbidity, health, fitness and physical activity, nine participants with central visual impairment (VI; age 76 ± 9 years; height 1.6 ± 0.1 m; BMI 24.9 ± 2.4) and nine participants with normal vision (age 75 ± 5 years; height 1.7 ± 0.1 m; BMI 25.7 ± 3.5) were deemed suitable for the study. Participants repeatedly walked up to and stepped over one of two different sized obstacles (5 cm low; 10 cm high).
The VI group statistically significantly increased the vertical distance that the lead and trail foot was lifted over the obstacle (p < 0.024, Fig. 1) and had statistically significantly lower horizontal velocity in the lead and trail foot when negotiating the low obstacle only (p < 0.021) compared to normals.
Adaptations in step ascent control among the VI group are indicative of a cautious stepping strategy to reduce the risk of tripping/falling, which is attributed to the degraded or impoverished central visual field information.
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