Visual field restorative rehabilitation after brain injury

About 20%-30% of patients undergoing neurological rehabilitation report visual field defects, one of the most frequent of which is homonymous hemianopsia (loss of the same half of the visual field in both eyes). There is still no consensus as to whether homonymous hemianopsia is best treated in a restorative or compensatory manner. The aim of this review is to describe the effects of restorative rehabilitation, whose long-term efficacy is still being debated. We analyzed 56 articles describing the use of various techniques used to promote visual field recovery but concentrating on two approaches: "border training," which involves exercising vision at the edge of the damaged visual field, and "blindsight training," which is based on exercising unconscious perceptual functions in the mild of the blind hemifield where the scotoma is deep. Both techniques have been supported by functional imaging studies showing evidence of cortical rearrangement (plasticity) after rehabilitation. Although no formal meta-analysis was possible, the results of a semiquantitative evaluation suggested that the improvement in visual skills obtained is related to the type of training used: Border rehabilitation seems to improve the detection of visual stimuli, whereas blindsight rehabilitation seems to improve their processing. Finally, the addition of transcranial direct current stimulation seems to enhance the effects of visual field rehabilitation.