Corneal differences between healthy and subclinical patients assessed using two different corneal tomographers

PURPOSE: To analyze subclinical keratoconus topography indexes using Pentacam and Orbscan-II measurements to identify evidences for seeking sensitive indexes to screen and diagnose subclinical keratoconus. METHODS: Fifty healthy participants (50 eyes) and 40 patients with subclinical keratoconus (40 eyes) were included. Seven common parameters including corneal thickness at the thinnest point; minimum curvature of the front surface (minimum simulated keratometry value, SimK's Min); maximum curvature of the front surface (maximum simulated keratometry value, SimK's Max); the frontal corneal surface best-fit spherical radius of the curvature; the back corneal surface best-fit spherical radius of curvature; the anterior corneal surface height (anterior Diff value); and the posterior corneal surface height (posterior Diff value) measured by Pentacam and Orbscan-II between normal and subclinical keratoconus eyes were compared. RESULTS: Statistical differences between the healthy and subclinical keratoconus groups (p<0.01) were found in all corneal parameters measured using both devices. Differences in the minimum curvature of the front surface (SimK's Min), thinnest point, anterior Diff value, and posterior Diff value were significant between Pentacam and Orbscan-II in the subclinical keratoconus group (p<0.05). CONCLUSION: The findings of this study identify the differences between normal and subclinical keratoconus eyes at the minimum curvature of the front surface, maximum curvature of the front surface, frontal corneal surface best-fit spherical radius of curvature, back corneal surface best-fit spherical radius of curvature, Anterior Diff value, and Posterior Diff value measures using Orbscan II and Pentacam that can help eye care practitioners clinically diagnose subclinical keratoconus.