An eye tracker includes at least one illuminator for illuminating an eye, at least two cameras for imaging the eye, and a controller. The configuration of the reference illuminator(s) and cameras is such that, at least one camera is coaxial with a reference illuminator and at least one camera is non-coaxial with a reference illuminator. The controller is adapted to select one of the cameras to be active to maximize an image quality metric and avoid obscuring objects. The eye tracker is operable in a dual-camera mode to improve accuracy. A method and computer-program product for selecting a combination of an active reference illuminator from a number of reference illuminators, and an active camera from a plurality of cameras are provided.