Inter-Eye Vault Differences of Implantable Collamer Lens Measured Using Anterior Segment Optical Coherence Tomography

Purpose The distance between an implantable collamer lens (ICL) and the crystalline lens, namely vault, is a space regulated by the interaction of the ICL and the anatomical structures of the eye. This study analysed the differences in vault size between fellow eyes with similar anterior segment biometry. Patients and methods A retrospective case series analysed 109 cases of patients bilaterally implanted with EVO-V4c. Patients were analysed pre- and postoperatively using anterior segment optical coherence tomography. The range of vault inter-eye differences was defined as the 95% confidence interval of the differences. Bivariate correlation was applied to seek for associations between vault inter-eye differences with biometric and lens parameters (angle-to-angle, anterior chamber depth, crystalline lens rise, central corneal thickness, central keratometry, ICL spherical equivalent, horizontal compression, postoperative pupil diameter and vault). Results Mean vault inter-eye differences were similar between fellow eyes (26.0 ± 122.5 µm). The 95% confidence interval range of the differences was ±240.1 µm, nearly 50% of the cases presented vault inter-eye differences higher than 100 µm. The vault of the first operated eye explained 81% of the variance in the second eye vault. Vault inter-eye differences were positively correlated with the level of horizontal compression and with vault magnitude. Conclusion Vaults measured in fellow eyes may present considerable differences, which can reach 25% of the common vault range. This reflects some degree of baseline variability in the vault. Clinically, these differences assume special relevance in cases where low or high vaults are expected.