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Heather L. Whitaker, Neil O'Leary, David P. Crabb, Nicholas D. Smith, Aachal Kotecha; Reaching And Grasping In Glaucoma: The Effect Of Visual Field Defect Location. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5504.
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To investigate the effects of unilateral glaucomatous visual field (VF) defects on reaching and grasping.
In these preliminary analyses, we present data from 6 control and 11 glaucoma subjects with unilateral VF defects in one hemifield (6 with superior defects (GS),5 with inferior defects (GI)). 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 at 20cm or 40cm from the hand under 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. In addition, reaction times were measured using purpose written software.
Table 1 summarises the demographics and selected prehension results. Compared with controls and GS patients, GI patients had slower movement initiation (MO) and duration (DM), reaching dynamics (ttPD) and early grasp dynamics (ttPGA), under both binocular & monocular viewing conditions. Whilst control and GS patients had slower reaching dynamics under monocular conditions, these improved under binocular trials.
These early analyses suggest that patients with unilateral glaucomatous inferior VF defect have deficits in reaching and grasping behaviour under both monocular and binocular conditions compared with patients with superior defects. Further study is required to establish the effects of eye dominance, reaction time and other visual parameters on prehension kinematics.
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