Comparison of Anterior Segment Measurements With a New Swept-source Optical Coherence Tomography Biometer and a Scheimpflug-Placido Topographer

Purpose To assess the agreement of anterior segment measurements between a new swept-source optical coherence tomography biometer (ZW-30; TowardPi Medical Technology) and a Scheimpflug-Placido topographer (Sirius; Costruzione Strumenti Oftalmici) in normal eyes. Methods In this prospective study, measurement agreement was assessed in 56 right eyes of 56 healthy patients. One experienced operator obtained three consecutive measurements with both devices randomly. The comparative parameters were central corneal thickness (CCT), anterior aqueous depth (AQD), anterior chamber depth (ACD), mean keratometry, astigmatism magnitude (AST), J 0 and J 45 power vectors, and corneal diameter (CD). The paired t -test was used to compare the difference between the two devices. Pearson's correlation analysis and Bland-Altman plots with 95% limits of agreement (LoA) were calculated to evaluate agreement. Results The paired t -test showed statistically significant differences in all parameters ( P < .05). Correlation analysis showed high correlation, Bland-Altman plots indicated moderate to high agreement between the two devices. The 95% LoA of CCT, AQD, ACD, mean keratometry, AST, J 0 and J 45 power vectors, and CD ranged from −4.36 to 19.83 µm, −0.11 to 0.04 mm, −0.12 to 0.03 mm, −0.50 to 0.12 D, −0.29 to 0.39 D, −0.20 to 0.14 D, −0.17 to 0.13 D, and 0.18 to 0.80 mm, respectively. Conclusions Anterior segment measurements from the new SS-OCT biometer and the Scheimpflug-Placido topographer demonstrated high agreement in AQD, ACD, AST, and J 0 and J 45 power vectors. However, for CCT, mean keratometry, and CD, the moderate inter-device agreement suggests that results should be interpreted with caution when making comparisons. [ J Refract Surg . 2025;41(5):e413–e420.]