1. A method for measuring stable and reproducible electrode-tissue impedance, comprising preconditioning of an electrode-tissue interface, and a stimulation system for a visual prosthesis generating a stimulation signal to precondition the electrode-tissue interface, comprising: a computer; software, loaded in the computer, adapted to perform a stimulating method for a visual prosthesis having a plurality of electrodes; a video processing unit; and an implanted neuron-stimulator.