Purpose <p>To evaluate the long-term changes in retinochoroidal structure and perfusion status in highly myopic eyes following ICL V4c implantation, using ultra-widefield swept-source optical coherence tomography angiography (UWF-SS-OCTA) combined with a three-dimensional modelling algorithm.</p> Design <p>Prospective cohort study.</p> Subjects <p>Sixty-six highly myopic patients (132 eyes) underwent ICL V4c implantation surgery and completed one year of follow-up.</p> Methods <p>Retinal and choroidal parameters, including retinal thickness (RT), capillary plexus density, foveal avascular zone (FAZ), retinal curvature, choroidal thickness (CT), and three-dimensional choroidal vascularity index (3D-CVI), were measured preoperatively and at multiple postoperative time points using UWF-SS-OCTA integrated with advanced 3D analytic techniques. Repeated measures mixed-effects models were applied to compare the pre- and postoperative parameters and test the correlations between parameters.</p> Results <p>The surgical outcomes are satisfactory with a stable safety profile and no major complications. RT and retinal vascular density exhibited transient changes in one month postoperatively, and gradually recovered (<i>p</i> &lt; 0.05). Choroidal parameters, including CT and 3D-CVI, demonstrated a progressive and sustained postoperative increase across the 1-year follow-up, with the most pronounced changes observed in the foveal and perifoveal zones (<i>p</i> &lt; 0.001). Factors of surgical duration and axial length showed significant correlation to the retinochoroidal responses (<i>p</i> &lt; 0.05).</p> Conclusion <p>Our analysis based on UWF-SS-OCTA demonstrated that ICL implantation can cause the recoverable changes of retinal structure and perfusion status, and the sustained remodeling of choroidal vascular conditions one year postoperatively in high myopia.</p> <p>Trial registration number : ChiCTR2500108664, registered at the Chinese Medical Research Registry.</p>