ISO 19980:2005 is applicable to instruments, systems and methods that are intended to measure the surface shape of the cornea of the human eye. It is not applicable to ophthalmic instruments classified as ophthalmometers. ISO 19980:2005 defines certain terms that are specific to the characterization of the corneal shape so that they may be standardized throughout the field of vision care and have common meaning for all those who have occasion to participate in this area. ISO 19980:2005 specifies minimum requirements for instruments and systems that fall into the class of corneal topographers. It specifies tests and procedures that will verify that a system or instrument complies with the standard and so qualifies as a corneal topographer in the meaning of this International Standard. It specifies certain tests and procedures that will allow the verification of capabilities of systems that are beyond the minimum required for corneal topographers.