Serum Vitamin D Levels as Predictors of Response to Intravitreal Anti-VEGF Therapy in Diabetic Macular Edema: A Clinical Correlation Study

Our study explored the role of serum 25-hydroxyvitamin D [25(OH)D] levels as an indicator of response to intravitreal anti–vascular endothelial growth factor (anti-VEGF) therapy in patients with diabetic macular edema (DME), highlighting functional and anatomical outcomes linked to systemic biomarker profiles. In a cohort of treatment-naive diabetic patients, vitamin D status was correlated with post-treatment changes in central macular thickness (CMT) and best-corrected visual acuity (BCVA), illustrating layered therapeutic responses among deficient, insufficient, and sufficient vitamin D groups. Functional gains, measured as improvements in decimal BCVA, and anatomical improvements, defined by CMT reduction via spectral-domain optical coherence tomography (SD-OCT), were primarily detected in patients with sufficient vitamin D levels. Remarkably, patients with serum 25(OH)D ≥ 30 ng/mL revealed complete dual-response rates, while those in the deficient group manifested partial therapeutic efficacy, supporting the immunoangiogenic modulatory role of vitamin D. Statistical associations exposed a tight linear connection between baseline and final visual acuity and a pronounced inverse relationship between CMT and final vision, suggesting that vitamin D may play a role in treatment-mediated structural recovery. These results may imply that low vitamin D levels lead to subclinical endothelial dysfunction and impaired retinal barrier repair, possibly through dysregulated anti–vascular endothelial growth factor (anti-VEGF) signaling, chronic inflammation, and oxidative stress. Our findings underscore the need for and importance of further research of vitamin D status as an adjunctive biomarker in the clinical approach of personalized DME and validates the potential of circulating vitamin D evaluation in therapeutic classification and predictive eye care.