Prediction of Footplate Position after Implantable Collamer Lens Implantation Based on Iris and Ciliary Body Morphologies

Purpose: To investigate the factors affecting footplate position and its influence on vault characteristics following implantable collamer lens (ICL) implantation. Setting: Hunan Provincial People’s Hospital, Changsha, China. Design: Retrospective case series. Methods: This study included 124 patients (124 eyes). Ultrasound biomicroscopy (UBM) was performed to assess the iris and ciliary body morphologies and observe the footplate position. Using multiple linear regression, the relationship between various ocular and ICL parameters and the vault as well as the factors affecting the footplate distance (FD) were analyzed. Based on the FD, three groups were formed: group 1 (<500 µm), group 2 (500–1000 µm), and group 3 (>1000 µm). The distribution of the vault range after surgery was observed for the three groups. Results: Ciliary sulcus angle and FD significantly impacted the vault (adjusted R 2 =0.190, F=6.763, P<0.001), with FD being the most important factor influencing the vault (Beta=−0.383, P<0.001). Postoperative UBM revealed that the footplate was located at different positions in the posterior chamber, with the majority (52%) being located on the ciliary body. The average size of the four footplate orientations was 0.88±0.24 mm. Multiple linear regression analysis revealed that ciliary body thickness (CBT), iris curvature (IC), and ICL iris contact length (IRCL) significantly influenced the FD (adjusted R 2 =0.373, F=11.432, P<0.001). The vault range differed significantly among the three groups (X 2 =32.33, P<0.001). Conclusions: Different postoperative ICL footplate positions significantly affect the vault. CBT, IC, and IRCL can alter the position of the footplate from the expected position. This study provides reference for ICL size selection and vault prediction.