Table 2.

Multivariate topographic indices in keratoconus.

Multivariate indices	Description	Probable keratoconus	Clinical keratoconus
KISA% index	(K) × (I–S) × (AST) × (SRAX)	60–100%	>100% [22]
Keratoconus severity index KSI)	Neural network using ten different topographic indices	15–30%	>30% [18]
Keratoconus prediction index (KPI)	Uses a combination of indices: SimK1, K2 Sim, UPS, DSI, OSI, CSI, IAI and AA, and a linear discriminant function	Not designed for detecting suspects	>0.23 [19]
Modified Rabinowitz/McDonnell index	Calculated from K central and I–S values	Not designed for detecting suspects	Maps with central corneal power >47.2 D and/or an I–S value >1.4 D [23]