The Evaluation of Enhanced Ectasia Display Mode in Screening for Keratoconus

ABSTRACT

PURPOSE: To estimate the utility of the enhanced ectasia display mode of Pentacam in discriminating keratoconus and keratoconus suspect from normal cornea. METHODS: Corneal topography was measured using the Pentacam in keratoconus, keratoconus suspect and a normal control group. A best-fit sphere (BFS) and an enhanced best-fit sphere (EBFS) were used as reference surfaces for corneal elevation measurements, and measured values from both the anterior and posterior surfaces were compared among the three groups. Receiver operating characteristic (ROC) curves were used to identify the optimal posterior corneal elevation cutoff points for maximal sensitivity and specificity in discriminating keratoconus and keratoconus suspect from the normal control group. RESULTS: Mean anterior and posterior corneal elevation were statistically higher in keratoconus than in keratoconus suspect and normal corneas. The optimal cutoff point of posterior elevation was 23 micrometer for the keratoconus group, and this value was associated with a sensitivity and a specificity of 96.7% and 98.6%, respectively for keratoconus. The optimal cutoff point of enhanced posterior elevation was 43 micrometer for the keratoconus group, and this value was associated with a sensitivity and a specificity of 96.7% and 95.5%, respectively. CONCLUSIONS: The enhanced ectasia display mode showed similar diagnostic power to that of the conventional elevation map, and the former could be more useful in a clinical setting due to the pronounced visualization of corneal elevation.