Repeatability of Swan600 and Its Agreement with Lenstar LS900 for Ocular Biometry in Children

Background/Objectives: To evaluate the repeatability of the Swan SW600 optical biometer and its agreement with the Lenstar LS900 in measuring ocular biometric parameters in children and adolescents. Methods: This prospective study included 778 children and adolescents aged 3–18 years. Parameters included axial length (AL), corneal radii in the flattest and steepest meridians (R1 and R2), central corneal thickness (CCT), anterior chamber depth (AD), lens thickness (LT), white-to-white distance (WTW), and axial length-to-corneal radius ratio (AL/CR). Repeatability of Swan SW600 was assessed using within-subject standard deviation (Sw), coefficient of repeatability (CoR), coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Agreement between devices was evaluated using paired t tests, ICC, and Bland–Altman analysis. Results: Swan SW600 repeatability was excellent for AL, R1, R2, CCT, AD, and AL/CR (ICC = 0.9918–0.9999) and lower for LT (ICC = 0.9060) and WTW (ICC = 0.8452). Agreement with Lenstar LS900 was strongest for AL (mean difference −0.050 ± 0.041 mm; 95% LoA −0.131 to 0.031 mm; ICC = 1.000), R1 (ICC = 0.986), R2 (ICC = 0.980), and AL/CR (ICC = 0.993). CCT and AD showed good agreement (ICC = 0.877 and 0.895), whereas LT showed lower agreement (ICC = 0.689). WTW showed poor agreement (ICC = 0.288). Age-stratified analyses showed consistently high agreement for AL, R1, R2, and AL/CR across all age groups, including children aged 3–6 years, whereas agreement for CCT, AD, LT, and WTW was more variable. Conclusions: The Swan SW600 demonstrates high repeatability and close agreement with the Lenstar LS900 for AL, corneal radii, and AL/CR in children and adolescents, including preschool-aged children; however, the weaker agreement observed for LT and particularly WTW suggests that these parameters should be interpreted with caution.