Comparison of corneal topographic indices of keratoconus versus normal eyes by using pentacam imaging

Purpose To compare the corneal topographic indices of keratoconus versus normal eyes by using pentacam imaging. Methods One hundred and fifty patients (300 eyes) from keratoconus clinic based on inclusion criteria and 149 nominees (298 eyes) for refractive surgery with normal cornea were selected from the Noor Eye Hospital, Tehran, Iran. Pentacam scheimflug measurements were performed for both groups based on standard measurement factors. Pentacam topography indices were recorded for each case. Results Average of topographic indices were evaluated and compared between two groups with T-test. The difference between two groups was significant. Effective indices in discrimination suspect from normal were evaluated by logistic regression. Sensitivity and specificity of indices were plotted by ROC curve. In order to diagnose suspect keratoconus, index of height decentration (IHD) and index of height asymmetry (IHA) had the most sensitivity and specificity values. Conclusions The results of this study showed that the index of IHD and IHA were the most sensitive and specific criteria in the diagnosis and discrimination between keratoconus and normal eyes. Based on sensitivity and specificity criteria, the given cut-points for each indices play an important role in detecting subclinical keratoconus from normal eyes.