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.