Diabetic Retinopathy

Intro & Pathophysiology - Sweet Retinal Damage

• Diabetic Retinopathy (DR): Most common microvascular complication of Diabetes Mellitus (DM). A leading cause of preventable blindness in working-age adults globally.
• Pathophysiology: Driven by chronic hyperglycemia.
  • Key mechanisms:
    • Polyol pathway: Aldose reductase converts glucose to sorbitol → osmotic stress, cellular damage.
    • Advanced Glycation End-products (AGEs): Accumulate, causing vascular dysfunction, ↑permeability.
    • Protein Kinase C (PKC) activation: Stimulates VEGF, promoting angiogenesis and leakage.

⭐ Pericyte loss is the earliest detectable histological change in diabetic retinopathy.

• Consequences: Breakdown of Blood-Retinal Barrier (BRB), capillary non-perfusion, retinal ischemia/hypoxia, leading to VEGF upregulation.

Classification & Features - Retina's Red Alerts

• Non-Proliferative DR (NPDR): No neovascularization.
  • Mild: ≥1 Microaneurysm (MA).
  • Moderate: MAs, dot/blot hemorrhages (H), hard exudates (HE), Cotton Wool Spots (CWS). Not severe NPDR.
  • Severe (4-2-1 Rule): Any 1 of:
    • Severe H/MA in 4 quadrants.
    • Venous beading (VB) in ≥2 quadrants.
    • IRMA (Intraretinal Microvascular Abnormalities) in ≥1 quadrant.
  • Very Severe: ≥2 criteria for severe NPDR.
• Proliferative DR (PDR): Neovascularization (NV) present.
  • NVD (NV of Disc) / NVE (NV Elsewhere).
  • Complications: Vitreous hemorrhage, Tractional Retinal Detachment (TRD).
• Diabetic Macular Edema (DME): Macular thickening/exudates. Commonest cause of vision loss. Can occur at any stage.

  ⭐ Neovascularization (NVD/NVE) is the hallmark of Proliferative Diabetic Retinopathy (PDR). oka

Diagnosis & Investigations - Eye Detective Tools

• Dilated Fundoscopy: Essential first step. Identifies microaneurysms, hemorrhages, hard exudates, cotton wool spots, IRMA, NVD, NVE.
• Key Imaging Modalities:
  • Fundus Photography: Baseline documentation; monitors progression.
  • Optical Coherence Tomography (OCT): Gold standard for DME detection & quantification; measures central macular thickness.
  • Fluorescein Angiography (FFA): Visualizes retinal circulation; detects leakage, macular ischemia, neovascularization. Critical for PDR.
  • OCT Angiography (OCT-A): Non-invasive; details microvasculature; alternative to FFA.
• Systemic Evaluation: Crucial for management: HbA1c, blood pressure, lipid profile, renal function.

⭐ Fluorescein Angiography (FFA) is crucial for detecting neovascularization and macular ischemia.

Management - Sight-Saving Tactics

• Core Aim: Prevent vision loss; stabilize/improve sight.
• Systemic Control: Essential foundation.
  • Glycemic (HbA1c < 7%), BP (< 140/90 mmHg), Lipid optimization.
• Ocular Therapies: Tailored to severity.
  • Laser Photocoagulation:
    • PRP (Pan-Retinal): For PDR, severe NPDR. Reduces neovessels.
    • Focal/Grid: For specific DME (less common).
  • Anti-VEGF Injections: (Ranibizumab, Aflibercept)
    • First-line for center-involving DME. Reduces permeability.
    • Adjunct for PDR.
  • Intravitreal Steroids: (Dexamethasone implant) Refractory DME; pseudophakic.
  • Pars Plana Vitrectomy (PPV):
    • Non-clearing vitreous hemorrhage.
    • Tractional RD involving macula.

⭐ Pan-Retinal Photocoagulation (PRP) is the gold standard treatment for high-risk PDR.

Screening & Prevention - Vision Vigilance Now

• Regular dilated fundus examination is paramount.

  ⭐ Annual dilated eye exam recommended for all diabetics: at diagnosis for Type 2 DM, and 5 years after diagnosis for Type 1 DM.

• Primary Prevention Pillars:
  • Intensive glycemic control (Target HbA1c < 7%).
  • Optimal blood pressure management (Target < 140/90 mmHg).
  • Dyslipidemia correction.
• Counsel on early symptom recognition and treatment adherence.

High‑Yield Points - ⚡ Biggest Takeaways

• Diabetic Retinopathy (DR): leading cause of new blindness in working-age individuals.
• Duration of diabetes: most significant risk factor for DR development.
• Microaneurysms are the earliest sign of NPDR; also see hemorrhages, exudates, CWS.
• PDR is marked by neovascularization (NVD/NVE), risking vitreous hemorrhage and TRD.
• Macular Edema (CSME): can occur at any stage, primary cause of visual impairment.
• Pan-Retinal Photocoagulation (PRP): standard treatment for high-risk PDR.
• Anti-VEGF injections: vital for macular edema and adjunctive in PDR.