Patent ID: 8457753

Claim:
A visual prosthesis comprising: a video processing unit receiving video data from a source of video data; an electronics package communicably coupled to said video processing unit; an electrode array communicably coupled to said electronics package and configured to stimulate visual neural tissue according to data from said video processing unit; the electronics package configured to apply stimulation signs having a magnitude and polarity; the video processing unit configured to: determine an off cell threshold of the visual neural tissue in response to the electronics package applying stimulation signals having magnitude and polarity; determine a transition point of the visual neural tissue in response to the electronics package increasing the magnitude of current of the stimulation signal, wherein the transition point is defined by a stimulus magnitude where on cells begin to overwhelm off cells; and memory in said video processing unit configured to store a map of stimulation patterns including said off cell threshold and said transition point wherein the visual prosthesis is further configured to selectively stimulate off cells and on cells of a patient according to said video data and said map stored in said video processing unit thereby achieving greater contrast as compared with on cell stimulation alone.