Reading Performance After Vision Rehabilitation of Subjects With Homonymous Visual Field Defects

ObjectiveTo examine whether increased visual functioning after vision-restoration training (VRT) coincides with improved reading abilities.DesignProspective noncontrolled open-label trial.SettingControlled laboratory setting for all diagnostic procedures that were conducted before and after 6 months of home-based VRT with telemedicine support.PatientsEleven subjects who had experienced a posterior-parietal stroke and have homonymous visual field defects.InterventionsSix months of VRT (1 hour daily repeated light stimulation in the partially damaged visual field).Main outcome measurementsVRT outcome measures were the number of detected light stimuli in eye-tracker controlled high-resolution perimetry and the spared visual field within the affected hemifield up to the relative and absolute defect visual field border (square degrees). Enlargements of spared visual field within the affected hemifield were correlated with changes of reading speed after VRT.ResultsAfter VRT, the number of detected light stimuli increased by 5.02 ± 4.31% (mean ± SD; P = .03). The spared visual field up to the relative defect visual field border increased from 18.09 ± 32.35 square degrees before to 137.40 ± 53.32 after VRT (P = .006), as well as for the absolute defect visual field border from 36.95 ± 33.77 square degrees before VRT to 152.02 ± 49.70 after VRT (P = .005). Reading speed increased from 108.95 ± 33.95 words per minute before VRT to 122.26 ± 30.35 after VRT (P = .017), which significantly correlated with increased spared visual field up to the relative defect visual field border (r = 0.73, P = .016). Measures of eye movement variability did not correlate with VRT outcome.ConclusionsVRT improved visual fields in parafoveal areas, which are most relevant for reading. This finding cannot be explained by changes in eye movement behavior. Because of a significant association between improvements of parafoveal vision and reading speed, we propose that patients with homonymous visual field defects who have reading deficits may benefit from visual stimulation by training.