Drug delivery to the eye still is a challenge due to its intricate anatomical structure. Posterior segment delivery is much more challenging due to the acellular nature of the vitreous humor and the longer diffusion distance to the retina. Iontophoresis is a noninvasive technique that facilitates the movement of charged drug molecules into tissues by an electric field. Using iontophoresis, it is possible to achieve therapeutic concentrations faster by modulating the intensity and duration of the applied current. Transscleral iontophoretic delivery is gaining pace and is considered as an alternative for a safe and more effective treatment to retinal disorders. This chapter intends to highlight various aspects of iontophoresis, with a special emphasis on transscleral delivery of drugs and drug-loaded nanocarrier systems for treating disorders in the back of the eye. Finally, a section on toxic effects of iontophoresis to various ocular tissues is included. © Springer International Publishing AG, part of Springer Nature 2018. All rights reserved.