Alterations in Macular and Peripapillary Vessel Density Following Implantable Collamer Lens Surgery in Highly Myopic...

To investigate early postoperative microvascular and structural changes in the macular and peripapillary regions after posterior chamber phakic intraocular lens (ICL) implantation in high myopia.

This prospective cohort included 122 eyes of 61 patients with high myopia undergoing ICL implantation. Optical coherence tomography (OCT) and OCT angiography (OCTA) were performed preoperatively and at 1 day, 1 week, 1 month, and 3 months postoperatively. Outcomes included corrected distance visual acuity (CDVA), spherical equivalent (SE), intraocular pressure (IOP), axial length (AL), macular and peripapillary vessel density parameters, retinal thickness, choroidal thickness (CT), and choroidal vascularity index (CVI), analyzed globally and by sector.

At 3 months, SE and CDVA improved significantly (both P<0.05), while IOP remained stable (P>0.05). Global macular perfusion decreased, including total macular vessel density (MVD; Δ=-4.11, 95% CI -5.78 to -2.44; P<0.0001) and macular small-vessel density (MSmVD; Δ=-3.56, 95% CI -4.22 to -2.90; P<0.0001), with similar reductions across macular subregions. Layer-specific analysis showed reduced superficial vessel density (SVD; Δ=-3.61, 95% CI -4.51 to -2.70; P<0.0001), whereas deep vessel density (DVD) showed no significant global change (Δ=0.78, 95% CI -0.63 to 2.18; P=0.279), with regional heterogeneity. Peripapillary vessel density also decreased (OVD: Δ=-4.21, 95% CI -5.30 to -3.11; P<0.0001; OSmVD: Δ=-2.11, 95% CI -2.85 to -1.36; P<0.0001), with sectoral variation. AL was negatively correlated with several macular and peripapillary vascular parameters (all P<0.05). In an exploratory sub-analysis (32 patients, 64 eyes) with 2-year AL follow-up, mean AL change was not significant, but greater 3-month foveal CT reduction was associated with longer AL at 2 years (estimate=-0.003 mm/μm; P=0.008).

ICL implantation significantly improved visual and refractive outcomes and was accompanied by early macular and peripapillary microvascular and structural changes. Early postoperative CT changes may be associated with longer-term axial length outcomes.