Retinal Outcomes in Diabetes: Antihyperglycemic Therapy, EWDR, and Perioperative Considerations

Diabetic retinopathy (DR) is a common cause of vision loss in diabetes, and it often progresses without early symptoms. DR reflects injury of the retinal neurovascular unit (NVU), which includes neurons, Müller glia, astrocytes, endothelial cells, pericytes, and immune cells. Chronic hyperglycemia drives oxidative stress, advanced glycation end products-receptor for advanced glycation end products (AGE-RAGE) signaling, mitochondrial injury, and low-grade inflammation. These changes disrupt endothelial junctions, promote leukostasis, weaken pericyte support, increase basement membrane thickening, and lead to capillary dropout and hypoxia. Hypoxia-related signaling increases anti-vascular endothelial growth factor (VEGF) activity, which raises vascular leakage and supports neovascular disease. Glial stress and microglial activation add cytokines and reactive oxygen species, and neural dysfunction can appear early and can weaken neurovascular coupling. Modern diabetes care changes the short-term risk landscape because potent therapies can lower HbA1c quickly. Large and rapid HbA1c reductions can trigger early worsening of diabetic retinopathy (EWDR), mainly in patients with high baseline HbA1c and moderate-to-severe baseline DR. Semaglutide's retinopathy complication signal in SUSTAIN-6 fits an EWDR-like pattern that tracks with rapid glycemic improvement in vulnerable eyes. In parallel, surgery adds acute stress, inflammation, glucose swings, hemodynamic shifts, and medication interruptions. These factors can worsen microvascular instability during recovery. Current perioperative guidelines and regulatory recommendations describe glucose targets and medication safety considerations, including preoperative interruption of SGLT2 inhibitors to reduce euglycemic ketoacidosis risk; however, the retina-specific implications of these measures remain indirect. This review summarizes current evidence linking NVU biology, EWDR risk, and perioperative diabetes-related factors. It discusses how these factors may interact in patients with diabetes and how they may influence retinal outcomes. The review is intended to synthesize current evidence and mechanistic interpretations rather than to provide formal clinical practice recommendations.