Optometry and Vision Sciences - Theses
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ItemThe effects of ageing and visual field loss on visuomotor control( 2012)Aspects of visual localisation, such as foveal hyperacuity, decline with age. However, the effect of ageing on the visual localisation judgements required for goal-directed reaching movements has not been studied. It is also unknown whether pointing precision to such visual stimuli are altered with ageing. Further, the effects of visual impairment on these tasks are not understood. This thesis aimed to investigate the effects of ageing and compromised peripheral visual function on visual localisation and pointing precision. The first part of this thesis aimed to investigate the effects of ageing on visual localisation and pointing precision (Chapter 4). Experiment 1 consisted of a cohort of younger and older observers performing visual localisation and pointing tasks. The results suggest that both the visual localisation and pointing systems remain largely intact with ageing. However, the visual localisation precision of older adults was more affected by the removal of visual references than younger observers. These findings are encouraging for older adults; especially with the increasingly active part they play in the workforce, and society at large. In order to further probe the state of the older visuomotor system, the second part of this thesis investigated the pointing and visual localisation precision of older observers with compromised visual status (Chapter 5). Older adults with glaucoma, a chronic eye disease that results in reduced visual field sensitivity, were used as the model for compromised visual status in Experiment 2. Results suggest that patients with glaucoma show a reduced ability to locate objects both visually and manually. However, perimetry – a clinical measure of visual field sensitivity – provides only a small indication of the degree of this difficulty. Observers with glaucoma also showed a reduced benefit of binocularity compared with their older controls for visual localisation tasks, suggesting that reduced visual field sensitivity may inhibit aspects of binocular processing.