A controlled trial of specific visual rehabilitation therapy in patients with hemianopic alexia

Patients with an acquired right-sided homonymous hemianopia often complain of persistent text reading problems (hemianopic alexics (HA)); they lack essential visual information from their right visual field to help guide efficient reading scanpaths. Our hypothesis was that a specific visual rehabilitation method aimed at improving reading saccades would improve both reading speeds and scanpaths in a group of HA when compared to a sham visual rehabilitation therapy. Eighteen patients with HA were entered into two groups: one practiced with specific reading tapes daily for eight weeks (tapes group) while the other had sham therapy (spot-the-difference group) for four weeks and then crossed-over to tapes for a further four weeks. The tapes group showed significant improvements in text reading speed (repeated measures ANOVA, p  =  0.015: size of effect 18% improvement), while the sham group did not improve over the first period (spot-the-difference therapy, p  =  0.138) but did when they crossed over to the tapes (p  =  0.007: size of effect 23% improvement). Measures of eye-movement behaviour were also commensurate with this behavioural improvement. This is the first study to demonstrate the effectiveness of a specific behavioural eye-movement based therapy in hemianopic alexia in the context of a controlled trial.