Comparison of angle-to-angle distance using three devices in normal eyes.

Abstract

To compare the angle-to-angle (ATA) distance, and the repeatability and the reproducibility of these measurements among the three devices. We performed the ATA measurements in 26 healthy subjects using anterior segment optical coherence tomography (CASIA2, Tomey, Japan), the Scheimpflug camera (Pentacam HR, Oculus, Wetzlar, Germany), and the combined Placido-ring corneal topography and Scheimpflug camera (TMS-5, Tomey). We also compared the repeatability and the reproducibility of the ATA measurements among these three devices. The ATA in the CASIA2 group was significantly larger than that in the Pentacam group (Bonferroni test, p = 0.002), or that in the TMS-5 group (p < 0.001). The coefficient variation of the first and second ATA measurements for a single examiner was 0.44% in the CASIA2 group, followed by 0.84% in the TMS-5 group, and 1.92% in the Pentacam group. The coefficient variation of the ATA measurements for two examiners was 0.61% in the CASIA2 group, followed by 0.97% in the TMS-5 group, and 1.84% in the Pentacam group. The ATA distance measured with the CASIA2 was ~0.40 and 0.56 mm larger than that with the Pentacam and the TMS-5, respectively. The CASIA2 provided the highest repeatability and reproducibility of the ATA measurements, followed by the TMS-5, and the Pentacam. These three instruments cannot be used interchangeably in terms of ATA measurements.