A method and apparatus (100) for processing an image to determine one or more parameters of a contact lens suitable for a human or animal subject. The image comprises a plurality of pixels forming an image of at least part of one eye of the subject. The apparatus comprises: an iris detector (116) configured to determine a diameter of an iris of the subject a cornea determiner (118) configured to determine a diameter of a cornea of the subject based on the determined diameter of the iris and a contact lens determiner (120) configured to determine one or more parameters of contact lens for the subject based on the determined cornea diameter.
