Table 1.

Definition of the groups investigated in this study

Stage	Kmax	Morphological characteristics
Group I	<  48 dpt	Vogt’s striae, no corneal scars, corneal thickness ≥ 400 μm
Group II	48–53 dpt	No central scars, corneal thickness ≥ 400 μm
Group III	>  53 dpt	No central scars, corneal thickness ≥ 400 μm

Modified Krumeich classification system of keratoconus stages defined by the presented parameters