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Meghan Riley, Kristin Kelly, Tim Martin, Mary Hayhoe, Krystel Huxlin; Homonymous hemianopia alters distribution of visual fixations in 3-dimensional virtual environments. Journal of Vision 2007;7(9):289. doi: 10.1167/7.9.289.
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© ARVO (1962-2015); The Authors (2016-present)
Homonymous hemianopia, a consequence of unilateral damage in early visual cortex, is associated with abnormal gaze distributions. However, to date, hemianopic saccade and fixation patterns have been investigated with search tasks and static, two-dimensional displays. The goal of this study was to assess whether abnormal hemianopic gaze patterns also occur when visual tasks are performed under more naturalistic circumstances. We compared fixation patterns of four, long-standing hemianopes with those of four visually-intact controls when immersed in a virtual, three-dimensional environment. Eye position was recorded and categorized under both static and ambulatory conditions. For all conditions tested, hemianopes fixated significantly more frequently into the half of the virtual field of view corresponding to their blind hemifield. But while fixation distributions and dynamics were fairly similar between the two subject groups when subjects were stationary, hemianopic fixation distributions were significantly narrower than those of controls in the walking condition. Our results suggest that hemianopes' compensatory eye movements towards the impaired hemifield when examining static, two-dimensional images also occur in a naturalistic, three-dimensional environment. However, the abnormally narrow range of exploratory fixations observed under ambulatory conditions suggests a potentially maladaptive strategy that could explain many of the difficulties experienced by this patient population when immersed in dynamic, real-life environments.
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