ABSI Z80.23-2018 applies to instruments, systems and methods that are intended
to measure the shape of the cornea of the human eye over a majority of its area. The measurements
of the anterior and/or posterior surface in local areas may be of curvature and/or three dimensional
topographical measurements of the surface. The measurements may be used to derive
more global parameters used to characterize the surfaces. Instruments classified as ophthalmometers
or keratometers are not covered by this standard.