Effect of anterior segment structure on vault and position after implantable collamer lens implantation

Purpose: To evaluate the effect of anterior-segment structure on vault and position after implantable collamer lens (ICL) implantation using ultrasound biomicroscopy. Methods: The retrospective case-control study included insufficient vault eyes (750 µm). The preoperative biometric parameters of the anterior-segment structure and basic data between the three groups were analyzed using one-way analysis of variance. Results: There were significant differences (P < 0.05) between the three groups in maximum ciliary body thickness (CBTmax), iris-zonule distance (IZD), and trabecular-ciliary angle (TCA). The vault gradually decreased as CBTmax decreased and TCA increased. In the pairwise comparison, the CBTmax comparison between the insufficient vault (750 µm) group was statistically significant (P = 0.024, 95% CI: −0.17–0.017 µm); the TCA comparison between the insufficient vault (750 µm) group was statistically significant (P = 0.005, 95% CI: 1.78°–12.15°); The IZD comparison between the insufficient vault (750 µm) group was statistically significant (P = 0.037, 95% CI: 0.0027–0.1119 µm). The analysis of 284 ICL haptics locations showed that there were 16.67%, 32.69%, and 70.83% haptics located in the ciliary sulcus in three groups, respectively. Conclusion: The vault and ICL haptics position are related to anterior-segment structure. A thinner and posteriorly positioned ciliary body would increase the risk of low vault and fewer ICL haptics located in the ciliary sulcus after ICL implantation. This provides guidance for the selection of the ICL size and placement position before surgery.