The study population comprised 62 sixty-two patients with myopia (62 right eyes), 32 men (32 eyes) and 30 women (30 eyes), aged 26.0 ± 4.6 years (range, 21 to 37 y). The preoperative characteristics are summarized in Table 1. All the surgeries were successful. In 3 eyes, the postoperative IOP at 2 h was 21 to 30 mmHg, which was controlled by carteolol eye drops until normal. There were 5 eyes with IOP larger than 30 mmHg and were immediately lowered to less than 15 mmHg via primary incision drainage. All the patients had IOP within the normal range at postoperative 4 to 6 h and all the follow-up visits. The UBM examination at 1, 3, and 6 months showed that the ICL V4c loops were in the ciliary sulcus without rotation or displacement. Slit lamp microscopy showed that the ICL V4c and lens surfaces were transparent. The UCVA of all the treated eyes reached or exceeded the preoperative BCVA. There was no significant difference in IOP or ECD between the baseline and 6 months after ICL V4c implantation (P > 0.05, Table 2). There were no complications such as cataract, glaucoma, or ICL deviation.

The baseline IOP was 15.97 ± 2.13 mmHg. IOP at 1 day, 1 week, and 1, 3, and 6 months after ICL V4c implantation were 16.02 ± 1.58, 16.13 ± 1.49, 16.18 ± 1.35, 15.97 ± 1.29, and 16.16 ± 1.08 mmHg, respectively. The difference was not statistically significant (F = 0.875, P = 0.504, Table 2).

The ECD showed no significant difference between the baseline (2989.30 ± 140.78 cells/mm2) and 6-month (2958.44 ± 126.78 cells/ mm2) measurements (F = 1.23, P = 0.204, Table 2).

The postoperative CACD measurements at 1 day, 1 week, and 1, 3, and 6 months were 3.01 ± 0.23, 3.00 ± 0.21, 3.01 ± 0.20, 3.02 ± 0.19, and 3.03 ± 0.19 mm, respectively, which were all significantly less than that of the baseline CACD (3.19 ± 0.21 mm; F = 11.10, P < 0.001, Table 2). However, postoperative CACD stayed stable 1 day after the operation as there were no significant differences among the postoperative timepoints at 1 day, 1 week, and 1, 3, and 6 months (P > 0.05, Table 2).

The postoperative ACV measurements at 1 day, 1 week, and 1, 3, and 6 months were 104.31 ± 21.20, 109.35 ± 22.17, 110.71 ± 21.52, 111.77 ± 21.08, and 111.04 ± 19.74 mm3, respectively, which were significantly lower than the baseline ACV of 210.30 ± 27.7 mm3 (F = 288.38, P < 0.001, Table 2). Although it significantly increased at one week compared with one day (P < 0.001), it stayed stable at 1, 3, and 6 months. (P > 0.05, Table 2).

The postoperative vault continued to reduce significantly at 1 day, 1 week, and 1, 3, and 6 months, with vault measurements of 665.32 ± 184.03 µm, 597.42 ± 166.33, 574.68 ± 159.43, 570.65 ± 150.52 µm, and 567.90 ± 152.32 µm, respectively (F = 52.10, P < 0.001). However, it stayed stable at 3 months and 6 months, showing no significant difference when compared with the measurement at 1 month.

The n-ACA and t-ACA were comparable at baseline (t = 1.17, P = 0.25; Table 3), and post-operative timepoints 1, 3, and 6 months (t = 0.16, P = 0.86; t = 1.91, P = 0.06; t = 0.47, P = 0.64, respectively). The t-ACA was significantly wider than the n-ACA at the post-operative timepoints 1 day (t = 8.70, P < 0.001) and 1 week (t = 4.66, P < 0.001).

Compared with the baseline measurement, the n-ACA and t-ACA were lower by 17.9° (44.1%) and 18.02° (43.78%), respectively, 1 day after the surgery. Although all the postoperative n-ACA and t-ACA measurements were significantly lower compared with the respective baseline measurements (F = 1279, P < 0.001; F = 239.2, < 0.001, Table 3), the postoperative measurements at 1, 3, and 6 months were similar. Figure 2 also showed that the measurements stayed stable 1 month after the operation.

The nasal and temporal anterior chamber angle (n-ACA and t-ACA) changes over time after implantable collamer lens with a central hole (ICL V4c) implantation and anterior segment parameters

The n-ACA measurements were positively associated with the preoperative n-ACA, CACD, and ACV at 1 day, 1 week, and 1, 3, and 6 months after the implantation, but no association with baseline AL and WTW, and postoperative vault. (Tables 4) The t-ACA measurements were also positively associated with the preoperative t-ACA, CACD, and ACV at 1 day, 1 week, and 1, 3, and 6 months after the implantation, but no association with baseline AL and WTW, and postoperative vault (Table 4).