1. An eye tracking method for determining a position of an eye or a part of an eye in an image of an image sequence by performing a comparison between said image and a reference image, said process including: aligning a set of images of the eye or the part of the eye to a same retinal position by shifting one or more images of the set of images within one or more respective image planes; computing an enhanced reference image based on a combination of said set of aligned images; and determining said position of the eye or the part of the eye in said image of said image sequence by comparing said image of said image sequence and said enhanced reference image to yield a motion estimation between said reference image and said image of said sequence.