A method of determining the position of eyeballs within an image, the method including the steps of: (a) capturing a time series of image frames illuminated in a predetermined temporal manner by at least two spaced apart light sources, by at least one imaging sensor; (b) processing the image frames to determine specular reflection locations in the image frames; and (c) utilising the time series evolution of the location of the specular reflections to isolate corneal reflections from the determined specular reflection locations.