A method for detecting a pupil in an image of an eye, comprises analyzing the image, exploiting an expected shape of the pupil, to identify portions of the image that are candidate portions of the pupil. A first region of the image, which corresponds to a lower part of the pupil, is analyzed in preference to a second region of the image, which corresponds to an upper part of the pupil, so as to reduce or avoid errors arising from artifacts that tend to be present in said second region of the image. A computer or processor program and an apparatus for performing the method are also disclosed.