The present invention relates to a method for testing a retinal implant. After an implantable device for interfacing with retinal cells is provided, an external stimulus is applied to the implantable device so that the implantable device transmits a first pulse to a processing device through a wireless interface. When a conversion unit is controlled to gradually decrease an output voltage until the implantable device outputs an output voltage lower than a reference voltage, the implantable device transmits a signal different from the first pulse to the processing device through the wireless interface. The processing device determines a current value of a pixel unit according to a time difference between the first pulse and the signal.
