1. A system for automatically registering and tracking a respective position of at least one eye ( 181 ; 182 ) of a subject ( 180 ), comprising: at least one imaging device ( 150 ) adapted to register sequential image data (D EYE ) representing the at least one eye ( 181 ; 182 ), at least one light source ( 140 ) arranged to illuminate the subject ( 180 ), each of the at least one light source ( 140 ) having a well-defined position relative to the imaging device ( 150 ), the at least one light source ( 140 ) is adapted to: vary a spatial location of an illumination area (A ILL ) towards which at least one light beam (L) from the at least one light source ( 140 ) is directed, receive a control signal (C ILL ), and direct the at least one light beam (L) towards an illumination area (A ILL ) specified by the control signal (C ILL ), and a processing unit ( 170 ) adapted to receive the image data (D EYE ), and based thereon produce a position estimate of the at least one eye ( 181 ; 182 ), wherein the processing unit ( 170 ) is adapted to produce the control signal (C ILL ) based on the position estimate of the at least one eye ( 181 ; 182 ) such that the illumination area (A ILL ) includes the position estimate.