Eye detection is used as the basis for providing power management or other variations of operational parameters of a controlled device. The system includes an imager and eye detection processing which cooperate to detect light received from a person's eye. The eye detection processing generates an output that can be used for determinations regarding presence of one or more persons or presence of a specific person. This output is used as the basis for switching the controlled device between at least two power consumption states. Eye detection may also be used to allow a person to actively adjust operational conditions of the controlled device, since unnatural eye blinking patterns may be associated with particular commands.