Improving Peripheral Reading With Noninvasive Transcranial Electrical Stimulation of Early Visual Areas

Purpose: Noninvasive transcranial electrical stimulation (tES) of the primary visual cortex can reduce crowding in peripheral vision. We investigated the effect of two tES protocols, visual cortex transcranial direct current stimulation (tDCS) and transcranial random noise stimulation (tRNS), on reading using peripheral vision, a task that is limited by visual crowding. Methods: A double-blind, placebo-controlled experimental design was used. Forty-one heathy adults with normal visual acuity completed one active and one sham tES session. During each session, English sentences were presented one word at a time 10 degrees below fixation. The proportion of words read correctly was assessed before, during, after and 30 minutes after real or sham tDCS (n = 21) or tRNS (n = 20). Results: The tRNS elicited a small but significant performance benefit (P = 0.035), whereas tDCS had no effect. Strong within-session learning effects were observed for all conditions (P = 0.001). Conclusions: These results add to a growing body of evidence indicating that noninvasive stimulation of the visual cortex can enhance visual processing and may have applications in vision rehabilitation. Translational Relevance: Noninvasive brain stimulation may enhance how the brain processes visual input from a diseased eye, complementing standard eye-based treatments of retinal and macular diseases.