Comparison of anterior segment parameters in cataract patients with different axial lengths using IOL Master and Pentacam

To evaluate the agreement and clinical interchangeability of anterior segment parameters measured by Swept-Source Optical Coherence Tomography (SS-OCT, IOL Master 700) and Scheimpflug imaging (Pentacam HR) across a continuous spectrum of axial lengths (AL). This retrospective study consecutively included 294 cataract patients (294 eyes) divided into six AL subgroups. Central corneal thickness (CCT), anterior chamber depth (ACD), white-to-white (WTW) distance, and mean keratometry (Km) were measured under undilated conditions by a single technician. Relative reliability was evaluated using Intraclass Correlation Coefficients (ICC). Absolute agreement was analyzed using Bland-Altman limits of agreement (LoA) and compared against predefined clinical tolerance thresholds. One-way Analysis of Variance (ANOVA) was performed to determine whether inter-device measurement discrepancies (Δ) varied systematically across AL subgroups. Relative reliability was excellent for ACD, CCT, and Km (ICCs > 0.88), but moderate for WTW (ICC = 0.641). Bland-Altman analysis revealed consistent systematic differences. The 95% LoA widths for CCT (31.32 μm), WTW (0.826 mm), and Km (1.274 D) significantly exceeded a priori clinical thresholds. The LoA width for ACD (0.233 mm) marginally exceeded the strict threshold. Crucially, ANOVA demonstrated no statistically significant variations in measurement discrepancies across all six AL subgroups (all P > 0.05). Inter-device measurement biases between the IOL Master 700 and Pentacam HR are remarkably stable and are not exacerbated by extreme AL. These inherent biases stem from differing optical principles rather than patient-specific ocular geometries. Given that the LoA widths consistently exceed clinical tolerance thresholds, these devices are not clinically interchangeable for individual precise surgical planning.