1. A system for controlling one or more functions of one or more medical devices, the system comprising: an operator tracking unit arranged to track the eyes of the operator; an evaluation device arranged to evaluate the determined eye tracking; a control device arranged to control the function of the medical device; and an operating mode selector for selecting between four or more operating modes, at least one operating mode being of maximum safety which requires activating the operating mode selector and activating the operator eye tracking for the emission of radiation, at least one operating mode being fully automatic which requires only eye tracking for the emission of radiation, at least one operating mode being a deactivation mode which requires only activating the operating mode selector for the emission or stopping of radiation, and at least one operating mode being eye tracking that activates the emission of radiation, which continues until it is disconnected by activating the operating mode selector, or automatically when the operator's eyelids are closed.