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Diabetic Retinopathy

Diabetic Retinopathy: Pathogenesis and clinical findings Authors: Graeme Prosperi-Porta Lucy Yang Reviewers: Stephanie Cote Usama Malik Mao Ding Johnathan Wong* * MD at time of publication Family history of T1DM Genetics: (DR3, DR4, DQ non-asp genes) Ethnicity: White youth, African American, Hispanic, Asian-Pacific Islanders, and American Indigenous Type 1 Diabetes Mellitus (T1DM) (see Diabetes Mellitus, Type I for pathogenesis) Type 2 Diabetes Mellitus (T2DM) (see Diabetes Mellitus, Type II for pathogenesis) Polycystic Ovarian Syndrome Family history of T2DM History of Gestational Diabetes ↑ Body Mass Index ↑ Age Ethnicity: Indigenous Americans, African American, Hispanic Poor glycemic control Chronic high blood sugaràinflammatory response ↑ cytokines and growth factors including vascular endothelial growth factor (VEGF) Vascular permeability Retinal neovascularization Vascular endothelial dysfunction: basement membrane thickening, vascular cell death, vascular occlusion from platelet aggregation Retinal hypoxia Outpouchings of the weakened capillary walls or endothelial buds attempting to re-vascularize the ischemic retina Weakened blood-retinal barrier (BRB) allows for rupture into the deeper retinal layers Lipid deposits with sharp margins due to lipoproteins & other proteins leaking through the damaged blood-retinal barrier Nerve fiber layer infarcts from occlusions of the precapillary arterioles Retinal hemorrhages occur in the more superficial nerve layer Focal areas of saccular venous bulges due to significant retinal ischemia & endothelial wall weakening and damage Diabetic Retinopathy (DR) A complication of diabetes due to chronic hyperglycemia resulting in abnormal permeability and ischemia of retinal vessels Micro-aneurysms Dot/blot hemorrhages Hard exudates (yellow opaque solids on retina) Cotton-wool spots (cloudy translucent patches on retina) Flame hemorrhages (multiple opaque red patches) Venous beading (veins with areas of narrowing forming bead-like segments) Traction retinal detachment Bleeding into the vitreous humor Pericyte death, breakdown of endothelial tight junctions & basement membrane thickening damages blood-retinal barrier Damaged blood- retinal border leaks fluid into the retinal tissues Macular edema (swelling of macula) Mild Non-proliferative DR Moderate Non-proliferative DR Severe Non-proliferative DR Proliferative DR Presence of neovascularization Localized retinal ischemia causes upregulation of vascular endothelial growth factor causing fine, irregular & easily friable neovascularization in the disc, macula, and/or retina Neovascularization (fine loop networks of new blood vessels) Neovascular membranes in vitreous gel form vitreoretinal adhesions and contract Fragile vessels extending into the vitreous humor Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published June 28, 2017, updated May 18, 2023 on www.thecalgaryguide.com