Clinical Outcomes And Vault Prediction Accuracy After Implantable Collamer Lens (Icl) Implantation With Anterior Chamber Predictors Of Toric Icl Rotation

To evaluate short-term refractive and vault outcomes of Implantable Collamer Lens (ICL; STAAR Surgical, California, USA) implantation and to identify anterior chamber parameters predictive of postoperative rotational instability in toric ICL eyes.

SNU Eye Clinic, Seoul, Republic of Korea

This retrospective study included patients who underwent ICL implantation between March and August 2025 with ≥ 1 month follow-up, horizontal orientation targeting emmetropia, anterior chamber depth (ACD) ≥ 2.8 mm, and no pathology. Biometry was obtained using Pentacam (Oculus, Germany) and CASIA2 (Tomey, Japan), including white-to-white (WTW), ACD, angle-to-angle (ATA), anterior chamber width (ACW), and crystalline lens rise (CLR). ICL size was determined using CASIA2-based NK and KS formulas targeting approximately 500 μm of vault. Postoperative refraction, vault, vault prediction error (PE), absolute PE, and complications were analyzed. Reoperation cases for rotation were compared with uneventful cases to identify biometric predictors.

A total of 415 eyes received toric ICLs and 72 eyes received non-toric ICLs. At 1 month postoperatively, both groups achieved excellent refractive outcomes with stable vaults (528 ± 147 and 514 ± 168 μm, respectively). Absolute PE was lower with the KS formula than with the NK formula in both toric (113 ± 94 vs 153 ± 113 μm) and non-toric eyes (121 ± 106 vs 164 ± 120 μm). Reoperation for toric ICL rotation was required in 19 eyes. These eyes had significantly greater anterior segment parameters (AOD, TISA, ATA, and ACD) and lower CLR than those without reoperation. Greater vertical–horizontal discrepancies in ATA and ACW were also observed, indicating increased rotational instability.

ICL implantation showed excellent short-term refractive and safety outcomes, with the KS formula demonstrating superior vault prediction accuracy compared to the NK formula. Larger anterior chamber dimensions and significant vertical-horizontal asymmetry were associated with postoperative toric ICL rotation. In eyes at higher rotational risk, consideration of one size larger ICL and/or vertical orientation may enhance rotational stability without compromising vault safety.