Repeatability of OPD-Scan III and its agreement with Pentacam in measuring keratometry, astigmatism and axis in patients with cataract and moderate to high astigmatism

Abstract

Purpose To assess accuracy of OPD-Scan III in measuring keratometry, astigmatism and axis in patients with cataract and moderate to high astigmatism Materials and Methods Measurements were taken with OPD-Scan III and Pentacam in cataract patients with keratometric astigmatism (KA) more than 0.75 D. Keratometry in the steepest axis (Ks) and flattest axis (Kf), KA and axis, which are power vector components of astigmatism (J0 and J45), were evaluated. Intraclass correlation coefficients (ICCs) were used to assess repeatability. The Wilcoxon test was used to assess differences, the Spearman correlation was used to assess correlations, and the Bland-Altman method was used to assess agreement. Results Seventy eyes of 63 patients were included to analyze the repeatability of the two devices. The ICCs of Ks, Kf, KA, axis, J0 and J45 were 0.991, 0.995, 0.946, 0.883, 0.946 and 0.892, respectively, with OPD-Scan III. Seven hundred and thirty-two eyes of 516 patients were included to analyze the difference, correlation and agreement of the two devices. There were significant differences between the two devices in terms of Ks, Kf, axis, J0 and J45 (all p < 0.01). There were significant correlations between the two devices in each parameter (all p < 0.01). The 95% limits of agreement (LOAs) for Ks, Kf, KA, astigmatic axis, J0 and J45 were (-0.34, 0.44) D, (-0.24, 0.38) D, (-0.46, 0.48) D, (-10.20, 12.92)°, (-0.24, 0.24) D, and (-0.27, 0.35) D respectively.The 95% LOAs for the degree of IOL caculated according to parameter measured by OPD-Scan III and Pentacam was (-0.32, 0.22) D. Conclusions OPD-Scan III has a high accuracy for measuring keratometry, but its accuracy for measuring astigmatism and axis is poor in eyes with moderate to high astigmatism.