Long-term clinical observation on the safety and stability of implantable collamer lens with a central hole (ICL V4c) with unexpected vault

Objective  To evaluate the long-term safety and effectiveness of conservative observation in patients with unexpected vault (in this study, the unexpected vault ranges were defined as 760-1 230 μm and 160-249 μm) after posterior chamber implantable collamer lens (ICL) V4c with central hole implantation.

Methods  A retrospective cohort study was performed. A total of 57 patients (80 eyes) with unexpected vault after ICL V4c with central hole implantation in Dalian Third People’s Hospital from June 2015 to April 2020 were enrolled and managed with conservative follow-up. According to the vault at 1 month postoperatively, the patients were divided into the low vault group (<250 μm) of 14 patients (17 eyes) and the high vault group (>750 μm) of 43 patients (63 eyes), with a 5-year follow-up. The surgical safety and effectiveness index were evaluated at 1, 3, and 5 years after surgery. The changes in visual acuity, intraocular pressure, corneal endothelial cell density (ECD) and vault were compared between the two groups, and the influencing factors of postoperative vault were analyzed. This study was conducted in accordance with the principles of the Declaration of Helsinki. The research protocol was approved by the Ethics Committee of Dalian Third People’s Hospital (No. 2023-086-004), and written informed consent was obtained from all patients prior to surgery.

Results  At 1, 3, and 5 years after surgery, the effectiveness index and safety index were all greater than 1 in both groups. There was no significant overall difference in uncorrected visual acuity at different time points after surgery between the low vault group and the high vault group (Wald χ ² _group=1.146, P=0.284; Wald χ ² _time=8.921, P=0.063). There were statistically significant overall differences in ECD at different time points in the two groups ( F _time=12.671, P=0.001). In the high vault group, the ECD at 1 day, 1 month, 6 months, 1 year, 3 years and 5 years after operation were significantly lower than that before operation, the ECD at 1 month, 6 months, 3 years and 5 years after operation were all lower than that at 1 day after operation, and the ECD at 3 years and 5 years after operation was lower than that at 1 month after operation (all P<0.05). In the low vault group, the ECD at 1 month, 6 months, 1 year, 3 years and 5 years after operation were significantly lower than that before operation and 1 day after operation (all P<0.05). There were statistically significant differences in vault between the two groups at different time points after operation ( F _group=378.580, P=0.001; F _time=93.560, P=0.001). In the high vault group, the vault after operation decreased with time, and the pairwise differences were statistically significant (all P<0.05). In the low vault group, the vault at 1 month, 6 months, 1 year, 3 years and 5 years after operation were lower than that at 1 day after operation, the vault at 6 months, 1 year, 3 years and 5 years after operation were lower than that at 1 month after operation, and the vault at 1, 3 and 5 years after operation were lower than that at 6 months after operation, with statistical significances (all P<0.05). Multiple linear regression analysis results showed that lens thickness (LT) ( β=-524.798, P=0.001), horizontal sulcus-to-sulcus (STS)-(white-to-white) WTW ( β=-158.707, P<0.001), preoperative (anterior chamber volume) ACV ( β=-3.790, P=0.021), preoperative (anterior chamber depth) ACD ( β=729.715, P<0.001) and ICL size ( β=222.324, P=0.047) were the influencing factors of vault. The regression equation was vault=-472.311-524.798×LT-158.707×horizontal STS-WTW-3.790×preoperative ACV+ 729.715×preoperative ACD+ 222.324×ICL size ( R ²=0.412, F=7.150, P=0.001).

Conclusions  ICL V4c with central hole implantation in patients with unexpected vault ranges without secondary surgical adjustment shows good effectiveness, safety, and long-term stability. LT, ACV, ACD, horizontal STS-WTW, and ICL size are factors that influence whether the arch height of ICL is in the ideal range after surgery.