Anterior vault as a risk stratification marker for trabecular-iris angle reduction after implantable collamer lens implantation

To evaluate the clinical utility of the anterior vault (AV), as measured by anterior segment optical coherence tomography (AS-OCT), as a risk stratification marker for a postoperative trabecular–iris angle (TIA) ≤ 20° following Implantable Collamer Lens (ICL) implantation. Additionally, this study investigated postoperative alterations in iridocorneal angle dynamics after ICL placement. This retrospective, observational study was conducted at a single private hospital and included 185 eyes from 185 patients who underwent ICL implantation between January 2018 and December 2023. The primary endpoint was to evaluate the discriminative performance of AV for identifying eyes with postoperative TIA500 ≤20°. Secondary outcomes included preoperative and postoperative parameters associated with eyes at risk of developing postoperative TIA ≤ 20°. Postoperative nasal and temporal TIA500≤20º occurred in 29(15.7%) and 38(20.5%) eyes, respectively. In the nasal quadrant, multivariate analysis identified the white-to-white/anterior-chamber depth (WTW/ACD) ratio (OR: 35.66; 95%CI: 6.14–93.86; p = 0.0031), nasal AOD500 (OR: 0.09; 95%CI: 0.02–0.27; p = 0.0077), nasal TIA500 (OR:0.85; 95%CI: 0.78–0.93; p = 0.0002), and AV (OR:0.06; 95%CI: 0.01–0.31; p = 0.0007) as independent factors associated with postoperative TIA500≤20°. In the temporal quadrant, AV (OR: 0.10; 95%CI: 0.02–0.39; p = 0.0010) and preoperative temporal TIA500 (OR: 0.84; 95%CI: 0.78–0.91; p < 0.0001) were significantly associated with post-ICL angle narrowing. The negative predictive values (NPVs) for excluding a postoperative TIA ≤ 20° were high within this cohort’s prevalence parameters. In the nasal quadrant, NPVs ranged from 93.5% (AV) to 95.6% (preoperative-nasal TIA), while in the temporal quadrant, preoperative-temporal TIA showed the highest NPV at 97.8%, compared to 87.2% for AV. This study identified AV, WTW/ACD ratio, and preoperative angle metrics as key markers associated with postoperative TIA500 ≤20° after ICL implantation. AV proved to be a simple, clinically valuable marker to enhance risk stratification.