Figure 1.

Contact lens-related warpage (top) and keratoconus (bottom) are not distinguishable by anterior topography (i.e., mean power map) when both show inferior focal steepening. They can be differentiated by the OCT epithelial map, which shows matching focal thickening in warpage and thinning in keratoconus. The pachymetry map shows focal thinning in keratoconus, but not in warpage. The warpage map is the product of the PD maps of anterior topography and epithelial thickness. The warpage map is predominantly positive (red/yellow) for the warpage case (top) and predominantly negative (blue/green) for the keratoconus case (bottom). The ectasia map is the product of fitted Gaussian waveforms for the PD maps of anterior topography and pachymetry. It shows clear cone-like pattern in keratoconus, which is absent in warpage.