An implant apparatus comprising a plurality of photo sensors, a plurality of micro electrodes, a plurality of guard rings surrounding the micro electrodes and circuitry coupled to the photo sensors and the micro electrodes are described. The photo sensors may receive incoming light. The circuit may drive the micro electrodes to stimulate neuron cells for enabling perception of a vision of the light captured by the photo sensors. The guard rings may confine electric flows from the micro electrodes to the targeted neuron cells. The apparatus may be implemented in a flexible material to conform to a shape of a human eyeball to allow the micro electrodes aligned with the neuron cells for the stimulation.