Background: Multiple studies on recovery of hemianopsia after CVA report visual field enlargements after stimulation of the visual field border area. These enlargements are made evident by the difference between pre- and post-training measurements of the visual field. Up to now, it is not known how the visual field enlargement develops.
Aim: To study how the enlargement develops as a function of time.
Methods: 11 subjects were trained by stimulating the border area of their visual field defect using a Goldmann perimeter. We assessed the visual field border location with dynamic Goldmann perimetry before, after and during training (after each 10th training session). To monitor eye fixation, a video-based eye-tracker was used during each complete perimetry session.
Results: We found that visual field enlargement during training is actually a gradual shift of the visual field border, which was independent of the type of stimulus-set used during training. The shift could be observed while eye fixation was good.
Conclusion: Visual detection training leads to a decrease of detection thresholds in the affected visual field areas and to visual field enlargement. Training effects can be generalized to important daily-life activities like reading.