Diagnostic capacity of the keratoconus match index and keratoconus match probability in subclinical keratoconus

PURPOSE: To evaluate the diagnostic capacity of the Ocular Response Analyzer's keratoconus match index (KMI) and keratoconus match probability (KMP) classification in keratoconussuspect eyes. SETTING: Department of Ophthalmology, University Clinics Saarland, Homburg, Germany. DESIGN: Comparative case series. METHODS: The KMI and KMP parameters in keratoconus-suspect eyes and normal eyes (control group) were compared. The quantitative keratoconus percentage index was calculated for all suspect eyes. According to the thinnest corneal thickness (TCT), keratoconus-suspect eyes were divided into 2 subgroups: subgroup 1 (TCT <520 mu m) and subgroup 2 (TCT >520 mu m). The KMI's overall predictive accuracy was assessed using receiver operating characteristic (ROC) curves. The relationship between KMI and a series of Scheimpflug-derived keratoconus-related indices was evaluated using Spearman analysis. RESULTS: The mean KMI was 0.41 +/- 0.29 (SD) in the keratocon us-suspect group (50 eyes) and 0.94 +/- 0.29 in the control group (50 eyes) (P<.001). Nonsignificant KMI differences were detected between the keratoconus-suspect subgroups (subgroup 1, 27 eyes; subgroup 2, 23 eyes) (P=.059). Nonsignificant correlations were found between Scheimpflug indices and the KMI. The KMP identified 27.65% of control eyes as keratoconus suspect and 10.71%, 28.57%, and 3.57% of keratoconus-suspect eyes as being normal, having mild keratoconus, or having moderate keratoconus, respectively. The ROC analysis for the KM! indicated a predictive accuracy of 94% (cutoff point 0.72). CONCLUSIONS: The KMI seems to be a valuable index in the early diagnosis of keratoconussuspect eyes. The KMP identified a significant percentage of topographically defined keratoconus-suspect eyes as normal or keratoconic. (C) 2014 ASCRS and ESCRS