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Jean-Marie Hanssens, Melody Moulin, Remy Allard, Jocelyn Faubet; The impact of aging on postural reactivity generated by simulated ophthalmic lenses distortions. Journal of Vision 2009;9(8):1130. doi: 10.1167/9.8.1130.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The purpose of this study was to determine whether aging could have a significant impact on postural control in presence of dynamic optical distortions.
Methods: We used a full immersive virtual environment to simulate dynamic distortions normally produced by ophthalmic lens corrections for myopes and hyperopes. Two young and senior groups were tested and asked to stand still with feet together and arms crossed. Their task was to track a red ball with their eyes that was moving on the horizontal axis without moving the head. While tracking the ball, a dynamic distortion model was applied to the background room represented in a form of a grid. Body sway amplitude was calculated from the electromagnetic trackers positioned on the body.
Results: The data show that young subjects had a clear postural reactivity as a function of both negative and positive distortions. The body sway increased as a function of amplitude of the distortion demonstrating that it was the distortion itself that was generating postural reactivity. For the older observers, impact of distortion on postural reactivity was clearly lower than for young. Further, sway of older group was significantly lower regardless of distortion amplitude.
Conclusions: This is the first clear evidence that simulated ophthalmic lenses distortions have significant effects on postural control. Target pursuit tasks such as the one used here are often performed in naturalistic contexts. The present results have implications for understanding the different tolerances often expressed by older and younger observers to ophthalmic lens distortions. This would imply that new lens wearers of the older age group should have higher tolerances than new wearers from the younger age group. This aging effect could be due to the reduced resources of older observers for processing simultaneous sources of information (ball tracking vs. perceptual motion of background grid).
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