Measurement of central corneal thickness using Orbscan 3, Pentacam HR and ultrasound pachymetry in normal eyes

Purpose To assess the agreement between Orbscan 3, Pentacam HR and ultrasound pachymetry (Palm Scan AP 2000) in measuring central corneal thickness. Methods Prospective observational cross-sectional study of ninety-two eyes of 48 patients with normal corneas was conducted. Central corneal thickness was measured via Pentacam HR, Orbscan 3 and ultrasound pachymetry. Bland-Altman analysis was used to demonstrate agreement between various methods. Results Ninety-two eyes of 46 subjects were enrolled. The mean age was 29.67 years (18-59). The average measurements of central corneal thickness were 545.73 +/- 29.35 mu m, 549.34 +/- 29.14 mu m and 545.78 +/- 31.48 mu m for the Pentacam HR, Orbscan and ultrasound pachymetry, respectively. The three devices measurements are closely correlated, with Pearson correlation coefficient ranging from 0.868 to 0.929. The 95 % limits of agreement were 25.2 to - 18 mu m between Orbscan and Pentacam central corneal thickness, 25.2 to - 25.7 mu m between Pentacam and pachymetry central corneal thickness and 34.4 to - 27.2 mu m between Orbscan and pachymetry central corneal thickness. Conclusion In spite of advancement of Orbscan 3, still there are wide agreement limits between CCT measurements obtained via Orbscan 3, Pentacam HR and ultrasound pachymetry; thus, interchangeable use in clinical practice is not recommended.