Computer-based training of stimulus detection improves color and simple pattern recognition in the defective field of hemianopic subjects

In a previously conducted randomized placebo-controlled trial, we were able to demonstrate significant visual field enlargement induced by restitution therapy in patients with cerebral lesions [Kasten, E., Wuest, S., Behrens- Bamann, W., & Sabel, B. A. (1998c). Computer-based training for the treatme nt of partial blindness. Nature Medicine, 4 1083-1087.]. Visual field train ing was performed on a computer monitor for 1 hr per day over a period of 6 months. Since the procedure included only stimulation with white light, in the present study we investigated if this simple detection training had a transfer effect on color or form recognition in the trained area (i.e., in the absence of modality specific training). Answering this question would b e crucial for planning optimal restitution therapy: In case there is no tra nsfer of training effects to other visual modalities, a specific treatment of each visual function must be performed in order to achieve maximum benef it. Therefore, we analyzed the data from 32 patients with visual field defe cts who had participated in the original trial and whose form and color rec ognition had been investigated. The experimental group (n = 19, restitution training) experienced not only an increase of 12.8% correctly detected sti muli (PeriMa program, p <.05), but also an improvement of 5.6% in pattern r ecognition (PeriForm) and of 6.1% in color perception (PeriColor), respecti vely. In contrast, the placebo group (n = 13, fixation training) showed no significant changes from baseline to final outcome in any of the visual mod alities (PeriMa: 0.3%; PeriForm: -0.3%; PeriColor: 0.4%). Conventional peri metry yielded an increase of 7.8% detected stimuli in the experimental grou p, but only of 1.2% in the placebo group (p <.05). For form recognition and color perception, the differences between the results of the experimental and the placebo groups narrowly missed significance. However, correlations of diagnostic results showed that mainly those patients who had achieved vi sual field enlargement also improved in color and form perception: r =.67 ( P <.05) between PeriMa and PeriForm and r =.32 between PeriMa and PeriColor . We conclude that visual restitution training using a simple white light s timulus has at least some influence on improving other visual functions suc h as color and pattern recognition. This result supports the "bottleneck th eory" of visual restitution, i.e., training effects can be explained as a p rocess of perceptual learning and increased processing of information by re sidual structures surviving lesions of the primary visual pathways.