Rehabilitation of homonymous scotomata in patients with postgeniculate damage of the visual system: saccadic compensation training

Abstract

A systematic training procedure for patients with disturbed visual search was evaluated in 92 patients with postchiasmatic visual field disorders (VFD) and 30 VFD patients with additional leftsided visual neglect (VFD +). Visual fields and areas of visual search via saccadic eye movements in the scotomatous field (search field) were mapped perimetrically in all patients before and after training and after a follow-up interval (mean follow-up interval: 22 months). A significant increase of more than 20° of visual angle was found in visual search field in the scotomatous field during training. Search field remained stable at follow-up in both patient groups. In contrast, only minor, though significant increases in visual field size were obtained during search field training in some patients. Multiple baseline designs in 5 patients revealed that search field enlargements were training dependent and not related to spontaneous recovery, adaptation to test procedures or measurement variability. VFD + Neglect patients needed some 25% more therapy sessions than VFD patients to achieve the same amount of increase in visual search field. Frequent head movements had a deleterious effect on training progress. It is concluded that the presented training procedure can lead to a significant and stable improvement in visual search within 15 to 25 training sessions and hence to a better compensation of visual deficits in daily living in most patients with VFD and/or visual neglect.