Analysis of anterior chamber angle structural changes and associated factors after implantable collamer lens with central-port implantation

Abstract:

AIM: To analyze changes in the anterior chamber angle structure in patients with implantable collamer lens with central-port(ICL V4c)implantation, and to investigate their associations with preoperative anterior segment anatomical parameters.

METHODS: Retrospective case study. Patients with myopia or myopia combined with astigmatism who underwent ICL V4c implantation in the Refractive Surgery Center of the Department of Ophthalmology, the 2^nd Affiliated Hospital of Harbin Medical University between July 2024 and November 2024 were recruited. Preoperative and postoperative uncorrected visual acuity, best-corrected visual acuity, intraocular pressure, anterior chamber angle(ACA), white-to-white distance(WTW), anterior chamber depth(ACD), angle to angle distance(ATA), horizontal sulcus-to-sulcus distance(HSTS), vertical sulcus-to-sulcus distance(VSTS),crystalline lens rise(CLR), pupil diameter(PD), iris thickness at 750 μm from the scleral spur(IT750),maximal iris thickness(ITM), iris curvature(I-Curv), and iris cross-sectional area(I-Area), angle opening distance(AOD750), thetrabecular-iris angle(TIA750)and the trabecular-iris space area(TISA750)in the temporal, nasal, superior, and inferior directions,as well as the vault at various postoperative time points were measured.

RESULTS: The study involved 40 patients(79 eyes)with myopia or myopia combined with astigmatism who underwent ICL V4c implantation(10 males and 30 females)with the mean age of 24.73±3.79 y. Compared with preoperative measurements, at 1 mo postoperatively, the AOD750, TIA750, and TISA750 parameters at the four angles(temporal, nasal, superior, and inferior)all showed a significant reduction(P<0.01). Statistically significant differences in vault were observed at postoperative 1d(0.49±0.1), postoperative 1 wk(0.43±0.14), and postoperative 1 mo(0.41±0.14)(all P<0.001). Correlation analysis indicated that the postoperative state of the anterior chamber angle was jointly influenced by anterior chamber parameters(ACD, ATA, HSTS、VSTS), iris morphology(I-Area, IT750), pupil size(PD), and surgical factors(ICL size, early vault), and that the combination of influencing factors varied across different orientations. Regression analysis showed that ACD was positively correlated with all postoperative anterior chamber angle parameters(P<0.05). IT750 exhibited negative correlations with the temporal and inferior angles(P<0.05). I-Area was positively correlated with temporal AOD750 and TISA750(P<0.05), and PD had negative correlations with temporal TIA750 and nasal AOD750(P<0.05).

CONCLUSION: Postoperative anterior chamber angle narrowing is a common phenomenon after ICL V4c implantation. The degree of change exhibits a significant correlation with multiple preoperative anterior segment anatomical parameters. Preoperative comprehensive assessment of ACD, PD, and IT750 may facilitate the evaluation of the risk of postoperative angle changes and the enhancement of surgical safety.