An eye tracking system includes an eye camera and a scene camera for supplying video data to interlace electronics indicative of an image of the user's eye and an image of the scene observed by the user. A frame grabber is provided for digitizing the video data and for separating the eye and scene data into two processing channels, and a spot location module determines the location of a reference spot formed on the user's eye. The module includes an adaptive threshold and spot identification sub-modules for indicating parts of the eye camera image which have higher brightness, and for selecting a valid reference spot. A pupil location module determines the user's line of gaze, and a display for indicating the user's point of regard from the user's line of gaze determined by the pupil and spot location modules.