The aim of the project SoftRevision was to create a virtual reality software for the rehabilitation of
perceptual deficits acquired by a stroke incident. The term “neglect” describes the inability of patients to attend to objects to one part of the visual field located opposite to the side in which the stroke induced a brain damage. These patients are not blind in the neglected visual field but they cannot access the visual information at that side. For instance, they will not shift their gaze to that side even if a relative is sitting there.
The idea behind the project SoftRevision was to develop a rehabilitation method in which patients have to perform a simple task in virtual reality. In a virtual scene, presented in a head-mounted display, they had to pick up objects and had to put them in a box. While working on the task, the patients hold a virtual reality controller in their physical hands. The controller tracks the position of the hands and displays virtual hands at the corresponding locations in the virtual scene. The crucial manipulation of the software consists ion a mirror reversal between the real and the virtual hands. Patients thus had to move their left hand in order to control their right hand and vice versa. This manipulation allowed patients by visual guidance from the healthy visual side to shift their hands towards the impaired visual side, which they would avoid without the manipulation. By training to solve the task under this condition, patients might learn to move towards the impaired visual field even without the mirror reversal of the hands and thereby regain access again to their neglected visual field.
We were successful in developing a software application, supported by the company A4VR, based in Düsseldorf. We conducted a feasibility study in the Sankt Mauritius therapy clinic in Meerbusch in order to evaluate whether patients accepted the game. Indeed, they enjoyed playing the game and provided many useful comments that helped to develop an improved version of the software application. In an additional study, we tested the potential success of the software as a rehabilitation tool. We tested a group of patients over 10 separate sessions who played the game while their virtual hands were mirrored with respect to their physical hands. Before and after the series of testings, we estimated the neglect symptom strength with standardized neglect tests. We also tested a control group which played the game without the hand mirroring manipulation. We found that in both groups neglect symptoms were reduced after the 10 sessions of training. However, we did not find a statistically significant difference between the experimental and the control group. There is thus no evidence that allows us to argue that our software was responsible for the decrease in symptom strength. It might well be the case that the playing in virtual reality - even without the mirroring manipulation - led to the reduction in symptom strength. In order to evaluate this possibility more research is needed.
