Comparison of Horizontal Corneal Diameter Measurements Using the Orbscan IIz and Pentacam HR Systems

Abstract

Purpose: To compare 2 automated devices for measuring the horizontal corneal diameter [white-to-white (WTW) distance]. Methods: In this prospective comparative case series, the WTW distance was measured by independent examiners using the Pentacam HR and the Orbscan IIz in 101 eyes of 101 healthy refractive surgery candidates. Statistical evaluation was performed using the paired t test, Pearson correlation, and the Bland–Altman method for comparison of measurement techniques. Results: The mean WTW distance measurements were 11.76 ± 0.38 mm as obtained with the Pentacam HR and 11.66 ± 0.37 mm as obtained with the Orbscan IIz (P < 0.001). The measurements were highly correlated (Pearson correlation coefficient = 0.948; P < 0.001). The 95% limits of agreement for the Pentacam HR versus the Orbscan IIz were −0.14 to 0.33 mm. Conclusions: The observed differences in WTW distance readings between the Pentacam HR and the Orbscan IIz are not clinically relevant, and the 2 devices could be used interchangeably in clinical practice.