SummaryToday, different measurement techniques are used in clinical routine for detection and monitoring of keratoconus and progression of the disease. In this talk we describe topo‐ and tomographical paramenters for centered or decentered corneal ectasia in terms of central and classical keratoconus. We demonstrate how to evaluate progression of keratoconus and side asymmetry in bilateral keratoconus. With the use of modern tomographical instruments, ophthalmologists are able to differentiate entities such as central or classical keratoconus.