1. A method for measuring stable and reproducible electrode-tissue impedance, comprising: providing a stimulation system including 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 including at least one electrode; preconditioning the electrode-tissue interface by delivering a first stimulation signal, including charge balanced biphasic square wave current pulses for a duration suitable to precondition the electrode interface to the electrode, the duration being between 1 second and 10 minutes; stopping preconditioning at the end of the duration; measuring an impedance on the electrode at similar electrode-tissue interface conditions to the preconditioning step, after said preconditioning step within a predetermined delay; transmitting the impedance wirelessly to a computer; and estimating perceptual thresholds based on the impedance.