Sample size estimation For Phase I, a sample of 30 participants in each group will be stipulated to characterize differences in postural control and gait between individuals with congenital and acquired blindness. In Phase II, the same 60 participants will be randomly allocated into three groups (anodal tDCS over the somatosensory cortex, over the primary motor cortex, ando ver the visual cortex) to identify the area of the brain stimulated that results in the best effect on gait and postural control. Phase III corresponds to the randomized, controlled, double-blind, clinical trial, for which the sample size will be calculated considering the effects obtained in Phase II and both gait velocity and displacement of the center of pressure as the primary outcomes. The calculation will be performed considering the means and standard deviations obtained in Phase II, with a alpha of 0.05 and an 80% statistical power. The sample determined by the calculation will be increased by 20% to compensate for possible dropouts.