Figure 2.

(a) Diagrammatic representation of the exclusion zone calculated in the Belin/Ambrósio Enhanced Ectasia Display which is determined by the magnitude of astigmatism and not selected by the operator. Anterior & Posterior elevation data relative to the 'enhanced reference surface” calculated by determining the BFS from central 8.0 mm zone after excluding all the data from a 3.5-4 mm optical zone centered on thinnest pachymetry of cornea. (b) Diagrammatic representation showing the difference in elevation values between the standard Best Fit Sphere and the enhanced Best Fit Sphere in normal and ectatic corneas, thereby enhancing the subtle elevation changes of early ectasia which can be missed by using the standard best fit sphere