Ocular biometry agreement among ZW-30, IOLMaster 700, and sirius in cataract patients

Accurate ocular biometry is crucial for the success of refractive cataract surgery. This study aims to assess the consistency and differences of a new biometer, the ZW-30, compared with the mainstream devices IOLMaster 700 and Sirius in patients with cataracts. A total of 307 patients with cataracts (603 eyes) were included. The anterior chamber depth (ACD), central corneal thickness (CCT), white-to-white (WTW) distance, pupil diameter (PD), flat K (K1), steep K (K2), corneal astigmatism (ΔK), total keratometry (TK), total corneal astigmatism (TCA), astigmatism axis, kappa angle (κ), axial length (AL), and lens thickness (LT) were measured using the ZW-30, IOLMaster 700, and Sirius. The consistency between devices was evaluated using Bland-Altman analysis, the correlation of parameters was assessed using Spearman correlation analysis, and inter-device agreement equations were established. Strong correlations (r ≥ 0.7) and no statistically significant differences in mean values (p > 0.05) were found for ACD, CCT, AL, LT, and anterior corneal curvature (K1/K2) among the three devices, but the 95% limits of agreement (LoA) exceeded the clinical threshold. Total corneal parameters (TK/TCA) and κ angle showed strong correlations (r ≥ 0.5) among the three devices, with significant inter-device differences in mean values (p < 0.05) and 95%LoA exceeding the clinical threshold. Corneal diameter (WTW) had a weak correlation (r = 0.48) between the ZW-30 and Sirius, and differences in PD measurement methods led to systematic bias. The ZW-30 is consistent with the IOLMaster 700 and Sirius in terms of group trends for basic biometric parameters (ACD/CCT/anterior corneal curvature), but significant individual differences exist (95%LoA exceeding the threshold). Total corneal parameters (TK/TCA) and κ angle require cross-validation with Sirius. WTW and PD are not interchangeable between devices due to differences in measurement principles. Cross-device parameter conversion should be avoided in clinical practice to ensure the accuracy of refractive surgery.