Repeatability and Agreement of 2 Scheimpflug Analyzers in Measuring the Central Corneal Thickness and Anterior Chamber Angle,Volume,and Depth

Abstract

Purpose

To evaluate the repeatability and agreement of 2 Scheimpflug tomographies (Pentacam HR, Oculus GmbH; Sirius, CSO Inc.) in measuring the central corneal thickness (CCT) and depth (ACD), volume (ACV), and angle (ACA) of the anterior chamber.

Methods

Three consecutive measurements were performed in one eye of each subject, with both instruments. The following were evaluated: CCT, ACD, ACV, and ACA. Repeatability was assessed by the Friedman test and agreement was assessed by 4 different Wilcoxon tests for paired data.

Results

The study enrolled 30 patients. With Sirius tomography the Friedman test p values for testing homogeneity across measurements was with respect to CCT 0.320, ACD 0.315, ACV 0.171, and ACA 0.020; and with Pentacam CCT 0.191, ACD 0.010, ACV 0.704, and ACA 0.150. The Wilcoxon test p values for testing the measurement homogeneity between the corneal tomography Sirius and Pentacam showed the following: ACD 0.000, ACD 0.000, ACV 0.853, and ACA 0.000.

Conclusions

The measurements may be considered substantially stable for each corneal tomography and each variable, but the 2 corneal tomographies do not produce statistically equivalent measurements.