Neurovascular unit uncoupling in diabetic retinopathy: molecular mechanisms and stage-adapted therapeutic strategies

Diabetic retinopathy (DR) is a major neurovascular complication of diabetes and remains a leading cause of vision loss among working-age adults worldwide. Although DR has traditionally been classified as a microvascular complication, it is now increasingly recognized as a neurovascular degenerative disorder involving coordinated injury to neuronal, glial, vascular, and extracellular matrix components of the retinal neurovascular unit (NVU). The NVU provides the structural and functional basis for coupling neuronal activity to local blood flow and for maintaining retinal immune and barrier homeostasis. In diabetes, chronic hyperglycemia, oxidative stress, inflammation, metabolic dysregulation, impaired vascular endothelial growth factor (VEGF)/angiopoietin-Tie (Ang/Tie) signaling, abnormal intercellular communication, and epigenetic memory progressively disrupt the coordinated interactions among NVU components, leading to neurovascular uncoupling. This concept helps explain why retinal functional abnormalities and neurodegenerative changes may precede clinically visible vascular lesions. In this review, we summarize cell-specific NVU alterations and the molecular mechanisms that drive neurovascular uncoupling in DR. We also discuss how this framework may support earlier diagnosis, mechanism-based phenotyping, and stage-adapted treatment strategies. Established therapies, including anti-vascular endothelial growth factor (anti-VEGF) agents, corticosteroids, and angiopoietin-2 (Ang-2)/Tie-2-directed vascular stabilization, are considered together with investigational approaches targeting oxidative stress, inflammation, neuroprotection, metabolic reprogramming, epigenetic regulation, and drug delivery. Reframing DR as a diabetes-driven disorder of early NVU uncoupling may help shift clinical thinking from late vascular rescue toward mechanism-based neurovascular protection, precision phenotyping, and stage-adapted intervention.