Comparison of Color Light-Emitting Diode Corneal Topographer and Dual Rotating Scheimpflug-Placido Topographer

Abstract

Purpose: To compare measurements of anterior and posterior keratometric values, using a color light-emitting diode corneal topographer and a dual rotating Scheimpflug-Placido topographer.

Methods: Anterior and posterior corneal index measurements were performed using a color light-emitting diode corneal topographer (Cassini) and a dual rotating Scheimpflug-Placido topographer (Galilei G4) and then compared. The paired t-test, intraclass correlation coefficients (ICCs), and Bland-Altman plots were used to evaluate the agreement between measurements.

Results: Sixty postrefractive surgery eyes and 60 normal eyes were evaluated. Both the color light-emitting diode corneal topographer and the dual rotating Scheimpflug-Placido topographer provided highly repeatable corneal measurements (ICC > 0.969). The agreement levels between the 2 devices for anterior corneal power, astigmatism magnitude, and J0 and J45 values were ICC > 0.906 for the total group. However, the ICC values for posterior corneal power, astigmatism magnitude, and J0 and J45 values were lower than 0.681 for the total group.

Conclusions: The anterior keratometric values obtained by the color light-emitting diode corneal topographer and the dual rotating Scheimpflug-Placido topographer showed high agreement levels, but the posterior keratometric values showed lower agreement levels.

Figure 1

Bland–Altman plots showing the agreement between the posterior corneal index measurements from the 2 systems. The bold lines represent the mean difference between the 2 methods. The broken lines represent the 95% limits of agreement. (a) Normal group posterior simK, (b) refractive group posterior simK, (c) normal group posterior astigmatism magnitude, (d) refractive group posterior astigmatism magnitude, (e) normal group posterior J0, (f) refractive group posterior J0, (g) normal group posterior J45, and (h) refractive group posterior J45 (color LED, color light-emitting diode corneal topographer; DRSP, dual rotating Scheimpflug–Placido corneal topographer).