Clarification of Perceived Phosphenes Positions by tACS considering Electrical Current flow and Exposed Visual Retinae

Phosphene is a phenomenon that human can perceive a flash of light in the brain when the human's visual pathway is stimulated electrically or magnetically. Therefore, blind people can also perceive phosphenes even though their crystalline lenses are not functioning. There are great hopes that phosphenes can be used as visual information for a walking support system for blind people. However, the phosphenes induction mechanism has not as yet been clarified since the mechanism of the conventional theory is inconsistent with real experimental results in terms of the perceived phosphenes position. In this paper, a new hypothesis on the phosphenes induction mechanism, which focuses on exposed visual retinae and the stimulated area by electrical current, is posited based on the anatomical characteristics of eyeball. Through experimental evaluation, our hypothesis is successfully verified.