An artificial retinal system includes an external optical device having an image generator and a background light generator, and a retinal implant chip having a solar cell and a stimulus generator. The stimulus generator is disposed to receive a target image projected by the image generator and a background light provided by the background light generator, and receives the electrical power from the solar cell. The stimulus generator includes an image sensing stimulator operable to convert the target image into electrical stimuli, and a contrast enhancer for reducing effect of the background light on the electrical stimuli.