Comparison of biometry measurements and intraocular lens formula accuracy of two swept-source optical coherence tomography biometers

To evaluate the agreement between biometry measurements obtained using two swept-source optical coherence tomography (SS-OCT) devices - IOLMaster 700 and Eyestar 900, and to compare the predictive accuracy of multiple intraocular lens (IOL) power formulas using data derived from both biometers in a Southeast Asian population undergoing cataract surgery. This was a retrospective, single-centre study conducted on 189 eyes from 126 patients in Singapore. Biometry measurements including axial length (AL), flat anterior keratometry (K1), steep anterior keratometry (K2), flat posterior keratometry (PK1), steep posterior keratometry (PK2), lens thickness (LT), anterior chamber depth (ACD), central corneal thickness (CCT) and white-to-white (WTW) obtained from both the IOLMaster 700 and Eyestar 900 were analyzed for statistical differences, correlation, and agreement. A subset of 70 eyes was further analyzed to evaluate the predictive accuracy of thirteen traditional and modern IOL formulas using measurements from IOLMaster 700 and Eyestar 900. Statistically significant differences were observed between devices for AL, K1, PK1, PK2, LT, ACD, CCT, and WTW (p < 0.05), though most were not clinically relevant except for PK1 and PK2 (mean difference of 0.4D). Strong correlations (ρ/r = 0.924–0.999, p < 0.001) were found for all parameters except WTW which demonstrated moderate correlation (ρ = 0.757, p < 0.001). Bland-Altman plots revealed excellent agreement for AL, K1, K2, ACD, and LT. WTW showed good agreement, while CCT had moderate agreement with some outliers. PK1 and PK2 demonstrated poor agreement with consistent systematic bias. The centroid difference in keratometric astigmatism as well as posterior corneal astigmatism were both low. Using IOLMaster 700 and Eyestar 900 data, modern IOL formulas consistently outperformed traditional ones. The Cooke K6 formula had the lowest MAE (0.254 and 0.251, respectively), followed by EVO 2.0 and PEARL-DGS. Statistical analyses demonstrated superior accuracy and precision for modern formulas (Cooke K6, EVO 2.0, Kane, Olsen PhacoOptics) compared to traditional formulas like Hoffer Q and Holladay I. The predictive performance was consistent across both devices, supporting the interchangeability of measurements from both devices for standard eyes. The IOLMaster 700 and Eyestar 900 demonstrated high agreement and correlation in most biometry parameters, except for posterior keratometry. Both devices yielded similar high accuracy in IOL power prediction, particularly with modern formulas. • Biometry measurements between IOLMaster 700 and Eyestar 900 in Southeast Asian cohort • High agreement and strong correlations were observed except for posterior keratometry • Modern IOL formulas showed superior accuracy and precision across both devices • Findings support the interchangeability of biometry parameters in standard eyes