1. A system for tracking an eye, comprising: an optical device with a light emitting source and an optical system, wherein the light source is configured for illuminating the eye and the optical system is configured for providing multiple-images of the eye; an optoelectronic device for acquiring an image of the eye collected by the optical system; an image processor for isolating reflections of source illumination in the image and for isolating features of the pupil and extra-pupillary eye structure in the image, wherein isolating features comprises determining the position of such in the image and categorizing as to structure type, where the features are at least those of a pupil; a pupil-reconstructor for constructing a model of the pupil within the eye, wherein the model of the pupil is constructed from model parameters derived from pupil image features; a feature-matcher for matching extra-pupillary image features to a common template located by the model of the pupil; a feature-locater for locating matched features from multiple images in a coordinate system common to the optical device; and a gaze processor for estimating the visual line-of sight for the eye in the said coordinate system; wherein the multiple images are stereo-views about an optical axis of the system with centering on the eye-orbit.