Estimating Implantable Collamer Lens Vault From Scheimpflug-Derived Postoperative Anterior Chamber Volume Change in Chinese Eyes

Purpose: To compensate for Pentacam's (Oculus Optikgeräte GmbH) flaw in Implantable Collamer Lens (ICL; STAAR Surgical) vault assessment, which is the difficulty to clearly detect the ICL itself, for the improvement of Pentacam's performance in the follow-up after ICL implantation. Methods: One hundred fourteen eyes that had ICL implantation at Beijing Fenglian Eyecare Beau Care Clinic were pre-screened from January to December 2024 and were randomly divided into the formula establishment group (76 eyes) and the formula validation group (38 eyes). A regression formula was worked out with the perioperative variables measured by Pentacam to best correlate with postoperative ICL vault measured by anterior segment optical coherence tomography (AS-OCT) using Pearson correlations and multiple linear regressions in the formula establishment group, and it was then tested in the validation group. Results: ICL vault showed significant positive linear correlations with anterior chamber volume change (ΔACV) ( r = 0.845, P < .001), anterior chamber depth ( r = 0.441, P < .001), and white-to-white distance ( r = 0.342, P < .01). However, there was no linear correlation between ICL vault and ICL size/direction/anterior chamber angle ( P > .05). The estimation formula was: ICL vault (μm) = 1,710.94 – 157.81 × ICL size (mm) +13.20 × ΔACV (μL). The validation results showed that the mean absolute error, median absolute error, and root mean square error were 82.27, 77.54, and 99.31 μm, respectively. Conclusions: This study established the ICL vault estimation formula based on ΔACV measured by Pentacam to best correlate with vault measured by AS-OCT. It compensates for Pentacam's flaw in ICL vault assessment, which is the difficulty to clearly detect the ICL itself, and is especially valuable when AS-OCT is unavailable.