Figure 6.

Keratoconus Screening Indices in Sirius topographic Map. Symmetry index front & back (SIf, SIb) measures vertical asymmetry, positive values indicate an inferior hemisphere steeper than the superior, negative values indicate superior hemisphere steeper than the inferior. Keratoconus Vertex front& back (KVf and KVb)-highest point of ectasia on the anterior and posterior elevation maps. Baiocchi-Calossi-Versaci front & back (BCVf) and (BCVb) -presence of ectasia through analysis of coma and trefoil components of Zernike's decomposition of elevations in zones where keratoconus statistically arises