VISUAL-FIELD ENLARGEMENT AFTER COMPUTER-TRAINING IN BRAIN-DAMAGED PATIENTS WITH HOMONYMOUS DEFICITS - AN OPEN PILOT TRIAL

Brain damage is often accompanied by homonymous hemianopia, but few th erapeutic approaches exist for visual field deficits. In this open pil ot study we describe a computerized training program which may possibl y reduce the size of the 'blind' visual field in patients with homonym ous visual field deficits. Various stimuli to test light perception an d discrimination of colors and shapes were presented on a monitor whic h permitted the examination or training of the central section of the visual field up to about 25 degrees vertical and 40 degrees horizontal eccentricity. Eleven patients trained at home for 1 h each day for a total of 80-300 h. Their results were compared with those of three pat ients who opted not to participate in the training procedure or those with very little therapy. These latter subjects had a slight decrease in the visual field size after about 1 year. In contrast, the treatmen t group displayed a reliable enlargement of visual field size. This wa s revealed by a significant improvement in the detection of small ligh t stimuli, an increase in the ability to discriminate colors and a min or, but notable, improvement of shape discrimination in the blind area s of the visual field. Additional training of shape recognition led to further improvement of shape discriminations, even when the patients trained with very different kinds of shapes, e.g. lines or letters. Ou tcome depended on age of the patients and the size of the lesion, but it was independent of on-set of treatment and cause of the lesion. Onl y two of the 11 patients with treatment showed no significant improvem ent. This study suggests that regular home training of the 'blind' vis ual field with computer-controlled stimuli may lead to improvement in vision. However, because of the following methodological limitations r esults are only preliminary: (1) the trial did not contain a true plac ebo group, (2) the patients were not assigned randomly to a control or treatment condition, (3) the lack of defined inclusion criteria consi derably increased the variance in neuropsychological performance, (4) because the experimental design was not double blind, experimenter bia s cannot be ruled out, and (5) the conditions of the home training cou ld not be standardized. The results warrant a larger randomized, doubl e-blind controlled trial.