High myopia with shallow anterior chamber depth (ACD less than 2.8 mm) is not rare. This observational study aims to evaluate visual outcomes after implantation of the Visian Implantable Collamer Lens with a central hole (ICL V4c) in these patients. Methods: A prospective cohort of consecutive 51 eyes of 31 patients (20 to 42 years old) was followed for at least 12 months (average 15.35 ± 4.90 months, rangers from 12 to 25 months). The preoperative ACD was 2.74 ± 0.04 mm (2.65 to 2.79 mm).

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... rected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), intraocular pressure (IOP), manifest refraction, vault, and endothelial cell density (ECD) were measured during the follow-ups after surgery. Results: All surgeries were performed safely and no complication was observed during the follow-up. At the last follow-up, the safety index (postoperative CDVA / preoperative CDVA) was 1.33 ± 0.60 and the efficacy index (postoperative UDVA / preoperative CDVA) was 1.14 ± 0.54. After the surgery, no eye had decreased CDVA and 59% (30 eyes) of the eyes gained at least one line. Forty-seven eyes (92%) were within ± 1.0 D and 35 eyes (69%) were within ± 0.5 D of the attempted refraction. The mean postoperative vault was 380.00 ± 152.84 µm (90 to 700µm). The ECD was reduced by 8.38 ± 0.06% as compared to the preoperative value (p < 0.001). No significant change was observed in IOP (p = 0.061) at the last follow-up. Ultrasound Biomicroscopy (UBM) showed none of the eyes had trabecular-iris angle closed. Conclusions: In this prospective observational study, ICL V4c implantation in patients with high myopia and shallow ACD achieved satisfying and stable visual outcomes. Its long-term safety and stability require further investigation. Trial Registration: This trial was retrospectively registered on 05/08/2018 under the number (ChiCTR1800017594) Background Since approved by the FDA in 2005, implantation of Implantable Collamer Lens (ICLTM, STAAR Surgical, Nidau, Switzerland), a posterior chamber phakic intraocular lens, has been demonstrated a safe and effective way to correct high myopia [1, 2] . Advantages of ICL implantation include faster visual recovery, more stable refraction, and better visual quality than corneal refractive surgery [3] [4] [5] . However, an anterior chamber depth (ACD) no less than 2.80 mm is usually recommended [6] and