Provided is a method of determining a gaze point of an eye watching a visual display controllable by a display signal. The method comprises generating a display signal using a graphics card in order for the visual display to produce a screen pattern; receiving a signal encoding an image of the eye including a corneo-scleral reflection of the screen pattern; and determining, based on in part the geometry of said reflection, a gaze point of the eye, wherein said determining a gaze point includes utilizing the graphics card as a parallel processor.The image of the eye may be received directly at the graphics card. The graphics card may extract image features in the eye images. Reference illuminators may be used, and the screen pattern may be interlaced with a distinctive reference pattern.Further provided are a gaze-tracking system and a personal computer system adapted to determine a gaze point of a viewer.