Precision Phosphene Control Through Cutaneous Facial Electrical Stimulation

The application of weak pulsating electrical currents across the facial skin produces visual experiences called phosphenes. Through the precise control of the visuo-spatial orientation of phosphenes, information can be directly sent into the visual field as a means of visual guidance for the partially-blind. In a human trial (8 healthy individuals), the participants were asked to draw their visual percepts, while having eight select regions of their face electrically stimulated. The phosphene drawings were evaluated using various metrics such as sensitivity, specificity, and mass centroid. Out of the eight proposed stimulation sites, four stimulation sites (templar, left transorbital, left infraorbital, and transnasal configurations) produced the most reproducible phosphenes, with average sensitivity and specificity scores of 68.8% and 96.1% respectively. To the best of our knowledge, this was the first time that spatially resolved phosphenes were stimulated through cutaneous electrical stimulation, without any surgical intervention.