Unilateral application of cathodal tDCS reduces transcallosal inhibition and improves visual acuity in amblyopic patients

Amblyopia is a neurodevelopmental disorder characterized by visual acuity and contrast sensitivity loss, refractory to pharmacological and optical treatments in adulthood. We studied the response of the visual cortex to transcranial Direct Current Stimulation (tDCS) applied over the primary visual area (V1) contralateral to the “lazy eye”. Visual acuity (logMAR) was assessed before (T0), immediately after (T1) and 60′ following the application of cathodal tDCS (2.0 mA, 20′). At each time point, Visual Evoked Potentials (VEPs) triggered by grating stimuli of different contrasts (K90%, K20%) were recorded in both hemispheres and compared to those obtained in healthy volunteers. Cathodal tDCS improved visual acuity (Holm–Sidak, p