Electric Stimulation of Neurons and Neural Networks in Retinal Prostheses

A computational model is presented that can be used as a tool in experimental research in retinal implants. In this model a target volume (i.e., a probe cylinder approximating a bipolar cell) in the retina is chosen, and the passive Heaviside cable equation is solved inside the target volume to calculate the depolarization of the cell membrane. The depolarization as a function of time indicates that shorter signals stimulate better, as long as the current does not change sign during stimulation of the retina. The model is equally applicable to epiretinal, subretinal, and suprachoroidal vision implants.