Region-Specific Retinal and Choroidal Biomarkers Associated with Visual Outcomes After Anti-VEGF Treatment in Center-Involved Diabetic Macular Edema

Objective: This investigation sought to: (1) characterize anti-vascular endothelial growth factor (VEGF) therapy-induced choroidal structural modifications in center-involved diabetic macular edema (CI-DME) utilizing swept-source optical coherence tomography (SS-OCT) imaging, and (2) assess the predictive capacity of choroidal morphometric indices for visual functional prognosis. Methods and Analysis: This retrospective cohort study encompassed CI-DME patients received intravitreal anti-VEGF injections. Structural parameters, including retinal thickness, choroidal thickness, and choroidal vascularity index (CVI), were measured by SS-OCT pre- and post-treatment. Statistical evaluations included paired t-tests, Wilcoxon tests, Elastic Net regression, sensitivity analyses and prognostic analysis. Subgroup analysis was stratified by baseline characteristics. Results: 58 eyes from 53 CI-DME patients were included. Following a single dose of anti-VEGF injection, logMAR BCVA improved significantly from 0.694 ± 0.342 to 0.614 ± 0.429 ( P = 0.0103). Total choroidal volumes within the ETDRS grid decreased by 0.065 mm 3 ( P = 0.031). Retinal thickness significantly declined in all nine ETDRS subfields ( P < 0.001), while choroidal thinning was most prominent in the central (mean deviation: – 17.42 μm, P < 0.001), nasal inner ring (mean deviation: – 15.10 μm, P = 0.0038), and nasal outer ring (mean deviation: – 11.83 μm, P = 0.0249) regions. Elastic Net regression and sensitivity analyses identified changes in central retinal thickness and nasal outer ring choroidal thickness as key imaging biomarkers associated with BCVA gains. Prognostic analysis revealed that baseline nasal inner ring retinal thickness showed most association with post-treatment central retinal thickness, whereas visual acuity outcomes were closely linked to age and baseline temporal outer ring retinal thickness. Exploratory subgroup analyses demonstrated that eyes with thicker retinas and thinner choroids at baseline, as well as younger patients, appeared to receive more favorable ocular structural and visual responses. Conclusion: SS-OCT imaging revealed region-specific changes of the retinal and choroidal thickness after anti-VEGF treatment, providing a practical reference for monitoring and tracking therapeutic response in CI-DME. Keywords: center-involved diabetic macular edema, anti-vascular endothelial growth factor therapy, swept-source optical coherence tomography, choroidal vascularity index