AIM:To investigate the safety and efficacy of selecting implantable collamer lens(ICL)size for postoperative vaults using sulcus to sulcus(STS)and other data measured by ultrasound biomicroscopy(UBM), and to explore the relevant factors affecting vaults.

METHODS: Prospective case observational study. A total of 95 patients(188 eyes)with ametropia who underwent ICL size optimization and 90 patients(174 eyes)without ICL size optimization, from January to December 2022 and underwent regular follow-up for 6 mo were selected. Patients were divided into an optimized group and a standard group based on whether ICL size optimization was performed. The patients were followed up at 1 d, 1 wk, 1, 3, and 6 mo, and uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), refraction state, intraocular pressure(IOP), corneal status, anterior chamber depth(ACD), angle opening, vaults and corneal endothelial cell count were collected.

RESULTS: No significant difference in spherical equivalent, UCVA and BCVA was found between the two groups(all P >0.05). The safety index was 1.21±0.24 and 1.19±0.21 at 6 mo for the two groups, respectively, while the efficacy index were 1.18±0.22 and 1.07±0.26. The vaults at 6 mo for the two groups was 407.77±159.31 and 467.16±250.07 μm, respectively. In the optimization group, 92.0% of eyes achieved the desired vaults postoperatively, while 74.1% of eyes in the standard group reached the desired vaults. Both groups exhibited a slight downward trend in vaults over time, with no significant differences between the two groups(F=3.478, P=0.063). However, the standard group experienced 6 eyes of ICL replacement and 2 eyes of ICL removal due to acute angle-closure glaucoma induced by angle closure.

CONCLUSION: Selecting the ICL size and determining the implantation orientation based on sulcus to sulcus(STS)and other data measured by UBM provides good safety, efficacy, and predictability for postoperative vaults.