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Dorothe A. Poggel, Bernhard Treutwein, Berhard A. Sabel, Hans Strasburger; Make the clocks tick right: Influence of computer-based vision restoration therapy on temporal-information processing in partially blind patients. Journal of Vision 2007;7(9):527. doi: 10.1167/7.9.527.
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Background: Patients with visual field loss after cerebral lesions show impaired temporal-information processing in partially defective but also in perimetrically intact visual field regions (Poggel et al., CNS 2006). We investigated effects of a computer-based training designed to restore light detection on dynamic visual field properties in partially blind patients. Methods: In nine patients with cerebral visual field loss, we measured double-pulse resolution thresholds (DPR, minimum perceivable duration of temporal gap between two light pulses) and simple reaction times (RT) across the visual field, before and after three months of Vision Restoration Therapy (VRT). Patient performance was compared to normative values (Toelz Temporal Topography study, Poggel & Strasburger, 2004). Results: Perimetrically determined light detection performance (i.e. intact visual field size) increased over the three-months training period (30 minutes of training per day). Averaged over the entire visual field, DPR remained constant, but there was a slight improvement of RT (−21ms; p=0.327). However, DPR (−15ms; p[[lt]]0.001) and RT (−111ms; p[[lt]]0.001) improved markedly in areas of residual vision, with effect size depending on the level of intactness of the respective visual field region. Compared to performance of healthy subjects, patients' DPR and RT were still impaired after training, with large inter-individual variability between patients, however. Conclusions: Training-induced improvement of light detection in patients with visual field loss thus generalizes to dynamic visual functions. Temporal-information processing improves relative to baseline, but not all patients reach normal level of performance. The results show improvements of residual visual impairment that remain unnoticed in perimetric testing.
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