Comparison of normal and keratoconic corneas by Galilei Dual-Scheimpflug Analyzer

Abstract

Background and objective: To determine the efficacy of different Galilei Scheimpflug-Analyzer (GSA) parameters in discriminating between keratoconic and myopic eyes.

Patients and methods: GSA measurements were obtained for 67 patients (67 eyes) with keratoconus and 151 patients (151 eyes) with myopia or myopic astigmatism. Several parameters, provided by the software or derived from the elevation maps, were evaluated and compared for the two groups.

Results: Between the two groups, statistically significant differences were observed for all corneal parameters obtained by GSA (P<0.001) except for the anterior chamber depth (P=0.149). ROC analysis determined that posterior corneal elevation was the best predictive parameter (area under the curve: 0.99). The posterior corneal elevation, at a cut-off value of 18.5μm, had 98.5% sensitivity and 98.3% specificity in discriminating keratoconus from myopic eyes.

Conclusion: Elevation, pachymetric and keratometric parameters measured by the GSA, as well as the specific predictive GSA software parameters can effectively distinguish advanced keratoconus from myopic corneas. Also, keratoconus that is easily diagnosed by other means can be diagnosed easily by GSA software parameters.

Keywords: Anterior segment imaging; Clinical examination; Galilei; Keratoconus; Scheimpflug.