Electric Stimulation of the Retina

Two computational models to be used as tools for experimental research on the retinal implant are presented. In the first model, the electric field produced by a multi-electrode array in a uniform retina is calculated. In the second model, the depolarization of the cell membrane of a probe cylinder is calculated. It is shown how these models can be used to answer questions as to cross talk of activated electrodes, bunching of field lines in monopole and dipole activation, sequential stimulation, etc. The depolarization as a function of time indicates that shorter signals stimulate better, as long as the current does not change sign during stimulation.