The effects of compensatory scanning training on mobility in patients with homonymous visual field defects:A randomized controlled Trial

Background: Homonymous visual field defects (HVFD) are a common consequence of postchiasmatic acquired brain injury and often lead to mobility-related difficulties. Different types of compensatory scanning training havebeen developed, aimed at decreasing consequences of the HVFD by changing the use of eye movements.Aim: The aim of the present study is to examine the effects of a compensatory scanning training program (IH-CST) using horizontal scanning on mobility-related activities and participation in daily life.Method: The main interest of this study was to assess the effectiveness of training on mobility-related activities and participation in daily life. Visual scanning tests, such as dot counting and visual search, and the control measuresvisual functions and reading were included as well. First, it was examined how performance on scanning and mobility-related measures was affected in 49 patients with HVFD by comparing scores with scores of a healthy control group (n=25). Second, the effect of training was assessed using an RCT design, in which performance of 26 patients before and after training was compared to performance of 23 patients in a waiting list control group.Results: After training, self-reported improvements were found, accompanied by objective improvements in detecting peripheral stimuli and avoiding obstacles during walking, especially in dual task situations in which a second task limits the attentional capacity available for compensatory scanning. IH-CST only improved mobility-related activities in which detection of peripheral stimuli is important, while no improvement was found on tests that require other visual skills, such as reading, visual counting and visual search. Conclusion: This is the first RCT to evaluate the effects of a compensatory scanning training that is based on a systematic horizontal scanning rhythm (IH-CST). The results suggest that different types of compensatory scanning strategies are appropriate for different types of activities