Repeatability and comparability of corneal thickness measurements obtained from Dual Scheimpflug Analyzer and from ultrasonic pachymetry

Abstract

Background: To assess the repeatability and comparability of central corneal thickness (CCT) measurements obtained from the Galilei Dual Scheimpflug Analyzer (Galilei-DSA) and from ultrasonic pachymetry (USP) in normal eyes and in eyes following laser refractive surgery.

Methods: In this prospective observational study, 77 eyes of 39 patients with normal corneas and 39 eyes of 20 patients with prior laser refractive surgery were enrolled. All 116 eyes had three repeated measurements of central CCT with the Galilei-DSA first and then with USP by the same examiner. Reliability of both devices was assessed statistically, and CCT measurements by each were compared.

Results: The mean CCT measurement of normal eyes was 549.2 ± 30.5 μm and 548.5 ± 33.1 μm by the Galilei-DSA and USP respectively; the difference between the two modalities was -0.7 ± 7.1 μm (P = 0.365). In post-refractive surgery eyes, the mean CCT measured by the Galilei-DSA and USP was 500.4 ± 44.8 and 494.3 ± 50.3 respectively; the difference between the two devices was -6.2 ± 9.9 μm (P < 0.001). For the three repeated measurements, the mean standard deviation was 2 μm with the Galilei-DSA and 1.8 μm with USP in normal eyes, and 2.4 μm with the Galilei-DSA and 1.9 μm with USP in post-refractive surgery eyes.

Conclusion: The Galilei-DSA has high repeatability and excellent to moderate agreement with ultrasonic pachymetry when measuring CCT in normal and post-refractive surgery eyes.