Development and validation of virtual prism adaptation therapy

Hemispatial neglect is common after stroke and associated with poor functional recovery and social return. Among various possible treatments for neglect, prism adaptation therapy has been known to be effective to promote the recovery from neglect. However, the conventional prism therapy using a prism glass and real object has a few shortcomings. Prism lens has to be changed to adjust the degree of deviation by the prism and the hand trajectory has to be masked during therapy. To solve these problems in conventional prism therapy, we developed virtual prism adaptation therapy using immersive virtual reality and depth-sense camera. This system was applied to 4 healthy people to validate it. The experiment consisted of 4 phases, which were non-prism, 5-min-prism (10-degree deviation), 5-min-prism (20-degree deviation) and 5-min-non-prism (post-adaptation). The median values of pointing deviations for 30-second-block in each phase were plotted. Deviations to right side were observed during prism phase and left side deviations were observed during the post-adaptation phase, which is similar phenomenon compared to the conventional prism therapy. The virtual prism adaptation therapy could be a low-cost system to solve the problems in conventional prism adaptation therapy. Further research in more healthy people and patients is required.