An eye-tracking system includes light-sensing units, each light-sensing unit including at least three light sensors and converging lens to converge light signals towards one or more of at least three light sensors; and processor(s) configured to: collect sensor data from individual light sensors, sensor data being indicative of respective light intensities of light signals sensed by individual light sensors; determine direction from which light signals are incident upon light-sensing unit, based on differences in light intensities of light signals; determine orientation of user's eye relative to given light-sensing unit, based on direction from which light signals are incident upon light-sensing unit and light intensities of light signals; and determine gaze direction of user's eye, based on orientation of user's eye and position of light-sensing unit relative to user's eye.