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A. Kotecha, D. R. Melmoth, S. Grant, D. P. Crabb; Eye-Hand Co-Ordination Deficits in Glaucoma - An Exploratory Study. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1158.
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To examine whether patients with glaucoma exhibit differences in reaching and grasping (prehension) behaviour compared to normally-sighted controls.
Seven glaucoma patients and 4 controls with no ocular pathology participated.Infrared reflective markers were placed on the subject’s preferred hand for recording its movement in 3D-space using motion-capture units (ProReflex, Qualisys AB, Sweden). Subjects reached and grasped two cylindrical objects placed in 1 of 4 locations using 1 of 3 viewing conditions (binocular, left eye only, right eye only). Between 8 to 12 movements were performed under each condition, generating a minimum of 96 trials per subject. Various indices of prehension planning, execution and control were quantified.Visual fields (VF) were measured using standard automated perimetry (HFA; Zeiss-Humphrey Instruments) generating monocular mean deviation (MD) and pattern standard deviation (PSD) scores. Eyes were classed as ‘better eye’ or ‘worse eye’ based on MD score. Binocular VF sensitivity was estimated using the integrated visual field (IVF) score [Crabb DP et al, Br J Ophthalmol 82(11): 1236-1241,1998].Differences in prehension movement between patients and controls in each viewing condition were compared, with strict control fror multiple comparisons (defined as p<0.0001).
Table 1 summarises the demographics and selected prehension results. When compared with control subjects at each viewing condition, patients showed significantly slower movement initiation (MO), reaching dynamics (PV, ttPD) and early grasp dynamics (ttPG), suggesting this group had difficulties with object location. However, examination of the spatial aspects of the grasp (PGA, GOC), indicated no differences in the estimation of object size between subject groups.
This study provides some evidence that glaucoma patients with asymmetrical field loss and relatively minor binocular field loss show deficits in prehension behaviour compared with control subjects with normal VFs. Further study is required to assess the associations between field loss location on prehension kinematics.
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