1. A method of determining reflections of light to obtain coordinates of desired reflections from a predefined configuration of light, comprising: processing an image of an individual's cornea to determine multiple coordinates of reflections of light, respectively; iteratively: selecting from the coordinates a first and a second set of coordinates; computing from the first set of coordinates a transformation that transforms the first set of coordinates into first coordinates of a predetermined spatial configuration; and testing whether the transformation transforms also the second set into positions that match second positions of the predetermined configuration; selecting the coordinates of the desired reflections to be those first and second sets which are transformed into coordinates that match the first and second coordinates of the predetermined configuration.