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

Abstract

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), J₀ and J₄₅ 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, J₀ and J₄₅ 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 J₀ and J₄₅ 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.].