Improving visual rehabilitation strategies in patients with macular degeneration by combining perceptual learning with tRNS

Macular degeneration (MD) is the leading cause of legal blindness in people over 65 years old. This disease involves a progressive loss of central vision, forcing patients to rely on their residual peripheral vision to process their visual environment. In order to decrease their visual impairments, readaptation strategies such as perceptual learning (PL) have shown promising results in enhancing their residual visual functions. However, it requires prolonged training and evidence of generalization to untrained visual functions is limited. Recent studies suggest that combining transcranial random noise stimulation (tRNS) with PL produces faster and larger visual improvements in participants with normal vision. Thus, this approach might hold the key to improve PL effects in MD. To test this, two groups of MD participants were trained on a contrast detection task with (n  =  5) or without (n  =  7) concomitant occipital tRNS. The training consisted of a lateral masking paradigm in which the participant had to detect a central low contrast Gabor target. Transfer tasks, including contrast sensitivity, near and far visual acuity, and visual crowding, were measured at pre , mid- and post-tests. Combining tRNS and perceptual learning led to greater improvements in the trained task, evidenced by a larger increment in contrast sensitivity and reduced inhibition at the shortest target to flankers’ distance. The overall amount of transfer was similar between the two groups. These results suggest that coupling tRNS and perceptual learning has promising potential applications as a clinical rehabilitation strategy to improve vision in MD patients.