A new formula based on new parameters for predicting postoperative vault after posterior chamber intraocular lens implantation: a retrospective study

BACKGROUND: To investigate the parameters influencing vault after posterior chamber intraocular lens implantation, thereby establishing a formula to predict the vault after operation. METHODS: In this retrospective study, 61 patients (122 eyes) who underwent implantable collamer lens (ICL) implantation were enrolled consecutively from the Qingdao Eye Hospital of Shandong First Medical University, China, between August 2020 and October 2021. Comprehensive optometry, axial length, curvature, anterior chamber depth (ACD), lens thickness (LT), white-to-white distance (WTW), corneal thickness, sulcus-to-sulcus distance (STS), the distance between the sulcus-to-sulcus plane and the anterior crystalline lens surface (STSL), ciliary-to-ciliary distance (CTC) and the distance between the ciliary-to-ciliary plane and the anterior crystalline lens surface (CTCL) were recorded preoperatively. The vault was measured by ultrasound biomicroscopy at 1 month after operation. The correlation among vault, preoperative parameters and ICL size was analyzed. The accuracy and reliability of the prediction formula were verified by analyzing the postoperative correlation coefficient of actual and predicted vaults of the contralateral eye and through the Bland-Altman consistency test. RESULTS: Parameters significantly influencing the vault at 1 month after operation are ACD (r=0.260, P=0.004), LT (r=−0.338, P<0.001), WTW (r=0.240, P=0.03), STSL (r=−0.394, P<0.001), CTC (r=−0.199, P=0.03), CTCL (r=−0.328, P<0.001), ICL size (r=0.224, P=0.01) and ICL power (r=−0.231, P=0.01). The regression formula was as follows: vault (mm) = −2.179 − 0.227 * CTC (vertical) − 0.783 * CTCL (mean) + 0.472 * ICL size (fitting R=0.853, R2=0.727, adjusted R2=0.705). The predicted vault was 0.50±0.18 mm, and the actual vault was 0.56±0.24 mm. The Bland-Altman scatter plot showed a satisfactory agreement between actual and predicted vaults (−0.06 mm, 95% limits of agreement: −0.45 to 0.32 mm). CONCLUSIONS: ACD, LT, WTW, STSL, CTC, CTCL, ICL size and ICL power were the factors affecting vault after ICL implantation. The prediction formula with the new parameter CTCL was accurate and reliable.