1. A method of validating the identity of a person, said method comprising the steps of: capturing an image of at least part of a cornea of an eye of the person and deriving one or more geometric parameters for each of a plurality of points or areas across said part of the cornea; comparing each of the geometric parameters derived from the person's cornea with a corresponding reference geometric parameter for each of the points or areas of the cornea for that person; and validating the identity of the person based on the comparison of the geometric parameters for said points or areas.