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Caitlin Murphy, Janette Chu, Eoghan Landy, Jean-Christophe Campbell, Amy Phan, Olga Overbury; The Influence of Fixation Stability on Balance in Patients with a Central Scotoma. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5037.
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© ARVO (1962-2015); The Authors (2016-present)
Vision is second only to the vestibular system in terms of its contribution to balance. Research has shown that visually impaired people (VIPs) often have problems in this domain. Some major visual disorders damage the central retina. To compensate for the loss of a functioning fovea, those affected use their remaining peripheral retina to accomplish daily tasks. This sometimes results in the formation of an unstable, non-central fixation point. The purpose of this study was to determine if reduced balance in VIPs is related to unstable fixation.
Individuals with a visual acuity of 20/200 or better and a diagnosis of a retinal disorder, were recruited for this study. There were 44 participants (23 M and 21 F) ranging in age from 47 to 89 years. Fixation stability was determined using the Mirametrix Eye Tracker and participants were then divided into two groups: stable fixation and poor fixation. Functional balance was measured using the Timed Get-Up-and-Go (TUG) and the Berg Balance Scale (BBS). Balance confidence was assessed using the Activities-Specific Balance (ABC) Scale. The examiners conducting the balance tests were masked to the fixation status of the participants.
Performance on the TUG test was significantly different between the groups, with the poor-fixation group having a slower TUG time than the stable-fixation group, t (42) = 1.7263, p < .05. Clinically, taking more than 13.5 seconds to complete the task indicates an increased risk of falls. The poor fixation stability group had a mean score of 14.3 seconds. There was no significant difference in functional balance between the stable- and unstable-fixation groups as determined by the BBS. Subjects with poor fixation stability scored lower on the ABC scale compared to the stable fixation group, t (42) = -1.856, p < .05. However, their scores were not low enough to have any clinical significance.
Based on the TUG, VIPs with unstable fixation are at a higher risk of falls compared to those with stable fixation. Although there is a statistically significant difference between the two groups on the ABC scale, it is not great enough to conclude that those with poor fixation are at risk of falls.
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