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Sheema A. Khan, Greg A. Richardson, David F. Garway-Heath, Gary S. Rubin, Aachal Kotecha; Postural Stability In Patients With Glaucomatous Visual Field Loss. Invest. Ophthalmol. Vis. Sci. 2012;53(14):204.
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To examine if there are differences in postural stability between glaucoma patients and age-similar controls.
Glaucoma patients (G) were recruited from the clinics of Moorfields Eye Hospital, London, UK and control subjects (C) from the local community. Visual tests included logMAR vision, stereoacuity and standard automated perimetry (HFA; Zeiss-Humphrey Instruments) generating monocular mean deviation (MD) scores, from which binocular integrated visual field scores (IVF) were generated. Postural stability was measured using a force plate (Bertec 4060, Bertec Corporation, Columbus, OH) which measures the coordinates of the centre of foot pressure (CoP). Subjects were asked to fixate on a distant target. Each subject underwent three 30 second recordings of postural stability under each of 4 conditions; eyes open and closed on a firm surface and eyes open and closed on a foam surface. Global sway velocities (V) were calculated from the coordinates of the CoP. Median V values for each condition were calculated for each subject. The visual contribution to sway was calculated using the Romberg quotient RQ =V(eyes closed [foam])/V(eyes open [foam]). Data were compared using Mann-Whitney U test.
Demographic data and V results are presented in table 1. There were no significant differences in V between groups. However, there was a significant difference in RQ between groups (median RQ [interquartile range]:G 1.6 [1.2 - 1.9]; C 2.2 [1.7] - 2.5; z-stat = 3.0, p = 0.02). There was a weak, non significant relationship between RQ and IVF, such that those with a worse IVF had a lower RQ.
These interim analyses suggest that the visual contribution to postural balance during quiet stance is reduced in glaucoma patients compared with age-matched controls. This suggests that glaucoma patients may rely more on their vestibular and somatosensory systems to maintain balance.
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