Agreement of four biometers measuring corneal astigmatism parameters in cataract eyes with low astigmatism

Abstract Background To investigate the agreement of corneal astigmatism measurements in eyes with low corneal astigmatism using four devices: Pentacam, Sirius, IOLMaster 700, and iTrace. Methods This prospective observational study enrolled104 cataract eyes with corneal astigmatism ≤ 1.5D. All four devices were used to measure keratometry (Kf, Ks, Km), power vectors (J₀, J₄₅), and astigmatism classifications. The results were compared using the Friedma n t est, Lin's concordance correlation coefficient (CCC), Cohen's kappa, and Bland-Altman analysis. Results Significant inter-device differences were found for Kf, Ks, and Km (all P < 0.001), but not for J₀ or J₄₅. Excellent CCC (> 0.95) was observed among Pentacam, Sirius, and IOLMaster 700 for keratometry, whereas comparisons with iTrace yielded lower CCC (0.784–0.853). For J₀ and J₄₅, CCC values were poor (≤ 0.135), with wide 95% limits of agreement. Agreement for astigmatism type and magnitude classifications was moderate (kappa: 0.352–0.573), with significant systematic asymmetry only between Pentacam and iTrace (McNemar-Bowker, P = 0.006). Conclusions Pentacam, Sirius, and IOLMaster 700 are interchangeable for anterior keratometry in low-astigmatism eyes, but their wide limits of agreement for vector parameters suggest a caution in toric IOL planning. iTrace shows systematic discrepancies and should not be used interchangeably without recalibration.