â– LECTURE OVERVIEW: Diabetic Retinopathy is a microvascular complication of chronic diabetes, classified into Non-Proliferative (NPDR) and Proliferative (PDR) phases.
â– PATHOPHYSIOLOGIC MECHANISMS:
1. Sorbitol Depletion: Chronic hyperglycemia drives intracellular aldose reductase to convert glucose to sorbitol. Sorbitol accumulation causes osmotic stress, selectively destroying pericytes.
2. Microaneurysms: Loss of supporting pericytes weakens capillary walls, leading to microaneurysms and leakage.
3. Systemic Retinal Ischemia: Progressive capillary closures cause retinal ischemia.
4. VEGF Surge: Ischemic retinocytes synthesize and secrete high-yield levels of Vascular Endothelial Growth Factor (VEGF).
5. Neovascularization: Excess VEGF drives neovascularization—the growth of fragile, abnormal new blood vessels over the optic disc and retina.
6. Hemorrhage and Traction: These fragile vessels are prone to rupture, leading to vitreous hemorrhage and subsequent fibrous scarring that can cause tractional retinal detachment.
â– PROGNOSTIC CRITERIA & TIMELINE:
Patient outcome scales correlate heavily with diagnostic staging at presentation, age, pre-existing comorbidities, and biological markers of cellular dividing rates.
â– SYSTEMIC HOMEOSTATIC REMODELING:
Prolonged pathologic strain causes adjacent cardiovascular, renal, or endocrine systems to remodel dynamically to maintain overall tissue perfusion.
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🌟 Dynamic Clinical Key:
To prevent blindness, patients with proliferative diabetic retinopathy are treated with intravitreal anti-VEGF monoclonal antibodies (e.g., Bevacizumab, Ranibizumab) and pan-retinal photocoagulation (PRP) to ablate outer ischemic areas and reduce VEGF release. Regularly reassess clinical parameters to adjust long-term therapy. Intercept compensatory loops early before they turn into independent pathologic drivers.