Predictors of 1-year fibrosis in treatment-naïve neovascular age-related macular degeneration: the role of baseline OCTA-derived MNV vessel density.

BACKGROUND: To investigate baseline and post-loading optical coherence tomography angiography (OCTA) characteristics associated with 1-year fibrosis in treatment-naïve neovascular age-related macular degeneration (nAMD), and to evaluate whether baseline clinical variables combined with OCTA-derived biomarkers could improve fibrosis prediction. METHODS: This retrospective, single-center study included treatment-naïve nAMD eyes with type 1 or type 2 macular neovascularization (MNV) that completed a 3 + PRN anti-VEGF loading regimen and had at least 12 months of follow-up. High-quality OCTA images were required at baseline and at the post-loading visit, defined as within 1 week after completion of the three-injection anti-VEGF loading phase. OCTA quantitative parameters, including fractal dimension, branch points, endpoints, segments, and MNV vessel density, were measured within the manually delineated MNV region of interest. Baseline clinical and imaging characteristics were compared between fibrosis and non-fibrosis groups. Univariate and multivariable logistic regression analyses were performed to identify factors associated with 1-year fibrosis, and receiver operating characteristic (ROC) curves were used to assess predictive performance. RESULTS: A total of 72 patients (88 eyes) were included, of which 31 eyes developed fibrosis at 1 year and 57 did not. Compared with the non-fibrosis group, eyes that developed fibrosis had worse baseline best-corrected visual acuity (BCVA), greater baseline central macular thickness (CMT), and a higher prevalence of subretinal hyperreflective material (SHRM), retinal hemorrhage, type 2/mixed MNV, high pigment epithelial detachment, and intraretinal fluid. At baseline, the fibrosis group showed significantly higher MNV vessel density, whereas MNV fractal dimension showed a borderline difference. At the post-loading visit, MNV fractal dimension, MNV branch points, MNV endpoints, MNV segments, and MNV vessel density were all significantly higher in the fibrosis group. However, within-group comparisons between baseline and the post-loading visit revealed no significant changes in OCTA parameters in either group. In multivariable analysis, baseline BCVA (OR 1.162, 95% CI 1.024-1.319; P = 0.020), baseline CMT (OR 1.032, 95% CI 1.001-1.064; P = 0.043), and baseline MNV vessel density (OR 1.073, 95% CI 1.009-1.142; P = 0.025) remained independently associated with 1-year fibrosis, whereas SHRM did not. The combined model achieved the best predictive performance, with an area under the ROC curve of 0.787 (95% CI 0.688-0.874). CONCLUSIONS: Eyes with treatment-naïve nAMD that developed fibrosis within 1 year had worse baseline disease status and distinct OCTA microvascular characteristics. Baseline BCVA, baseline CMT, and baseline MNV vessel density were independently associated with fibrosis. Integrating conventional clinical and structural features with OCTA-derived MNV vessel density may provide complementary information for fibrosis risk stratification in nAMD.