Agreement of IOL power and axial length obtained by IOLMaster 500 vs IOLMaster 500 with Sonolink connection

Background The accurrate and expedient ocular biometry is essential for modern cataract surgery. IOLMaster 500, one of the most popular partial coherence interferometry (PCI) device, has been widely used. However, with the PCI device, it is difficult to obtain the axial length through densely opaque media. With the current version of IOLMaster 500, a unique feature is added to link with the Synergy immersion A-scan ultrasound (sonolink connection). In case of failure to measure axial length by IOLMaster 500, the axial length can be obtained by ultrasound, and then transferred to IOLMaster 500 for the IOL power calculation. This study aims to compare the results and evaluate the agreement between IOL power and axial length obtained by IOLMaster 500 and IOLMaster 500 with sonolink connection. Methods A prospective study of 60 eyes in 60 mild-to-moderate cataract patients was conducted under Institutional Ethics Committee approval. Keratometry (K) and axial length (AL) of all eyes were measured using IOLMaster 500 (Carl Zeiss, Germany), then IOL power was generated using Holladay 1 formula (group 1). After 5 min, the K measurements were repeated with IOLMaster 500 and the AL were measured again using the Synergy A-scan ultrasound (Accutome, USA). Then, the AL data were transferred to IOLMaster 500 via the sonolink connection to generate the IOL power using the same setting (group 2). The IOL power and AL were compared between the two groups, and the agreement was evaluated using intraclass correlation coefficient (ICC) and the Bland–Altman method. Results The mean IOL power in group 1 was 21.04 + 2.36 D and group 2 was 21.03 + 2.36 D. The mean AL in group 1 was 23.35 + 0.86 mm and in group 2 was 23.36 + 0.86 mm. There was no statistically significant difference in IOL power and AL between the two groups. The agreements in IOL power and AL between both groups were high (ICCs = 0.997 for IOL power and 0.993 for AL) Conclusions The IOL power and AL derived from both groups were similar. The agreements between them were high.