Apparatus is provided including an external device including, a mount, which is placed in front of an eye of a subject. A power source is coupled to the mount and emits energy toward the eye. An intraocular device is implanted entirely in the subjects eye, and includes a control unit, a plurality of stimulating electrodes, and an energy receiver, which receives the energy from the power source and generates a voltage drop in response. A plurality of photosensors detect photons and generate a signal in response. Driving circuitry is coupled to the energy receiver and to the photosensors, and drives the electrodes to apply electrical charges to a retina in response to the signals from the photosensors. The external device modulates the emitted energy, and the control unit demodulates the modulated energy to regulate an operation parameter of the intraocular device. Other embodiments are also described.
