Age-Related Macular Degeneration

AMD Basics - Dotty Vision Drama

• Leading cause of irreversible blindness in elderly (>60 yrs).
• Types:
  • Dry (Non-exudative/Atrophic): 80-90%; geographic atrophy.
  • Wet (Exudative/Neovascular): 10-20%; choroidal neovascularization (CNV).
• Risk Factors: Age, smoking, genetics (CFH, ARMS2), HTN, ↓antioxidants.

⭐ Drusen accumulation between the RPE and Bruch's membrane is the earliest clinically detectable feature of AMD.

Pathophysiology - RPE's Ruin

• Chronic oxidative stress & inflammation primarily target the Retinal Pigment Epithelium (RPE).
• RPE dysfunction: Impaired phagocytosis of photoreceptor outer segments, ↑ intracellular lipofuscin, cytokine release, oxidative damage.
• Bruch's membrane: Thickens, accumulates lipids & collagen (basal laminar and linear deposits), ↓ nutrient & waste transport.
• Drusen formation: Extracellular debris (lipids, proteins) accumulates between RPE & inner collagenous layer of Bruch's; soft drusen indicate higher risk.
• Dry AMD (Non-exudative): Leads to geographic atrophy (RPE & photoreceptor cell death).
• Wet AMD (Exudative): Characterized by Choroidal Neovascularization (CNVM) through breaks in Bruch's membrane.

⭐ VEGF (Vascular Endothelial Growth Factor) is a key mediator in the development of choroidal neovascularization (CNVM) in wet AMD.

Clinical Features - Signs & Symptoms

• Symptoms:
  • Gradual, painless, progressive bilateral ↓ central vision.
  • Metamorphopsia (Amsler grid distortion): straight lines appear wavy.
  • Central or paracentral scotoma (blind spot).
  • Difficulty with reading, recognizing faces, needing brighter light.
• Signs (Dry AMD):
  • Drusen (key finding):
    • Hard: small, yellow, well-defined.
    • Soft: larger, paler, indistinct borders (higher risk for CNV).
  • RPE changes: hyperpigmentation or hypopigmentation.
  • Geographic Atrophy (GA): advanced, sharply demarcated RPE/choriocapillaris atrophy.
• Signs (Wet AMD):
  • Choroidal Neovascularization (CNV) evidence.
  • Subretinal/intraretinal fluid, hemorrhage; lipid exudates.
  • Disciform scar (fibrovascular, end-stage).

⭐ Sudden onset of metamorphopsia or a central scotoma often indicates conversion to wet AMD.

Diagnostic Workup - Eye Spy Tech

• Fundoscopy: Drusen, RPE changes, exudates, hemorrhage.
• Amsler Grid: Metamorphopsia, scotoma screening.
• OCT (Optical Coherence Tomography): Detects fluid (SRF/IRF), drusen, RPE integrity; monitors therapy.
• FFA (Fundus Fluorescein Angiography): CNVM (classic/occult) detection, leakage patterns.
• ICG (Indocyanine Green Angiography): Occult CNVM with blood/pigment; choroidal circulation.

⭐ Fundus Fluorescein Angiography (FFA) is the gold standard for visualizing and classifying CNVM patterns, while OCT is crucial for detecting and monitoring fluid.

Management - Fighting Blindness

• Overall Goals: Preserve/improve vision, slow AMD progression.
• General Measures:
  • Smoking cessation (critical).
  • Healthy diet (green leafy veg, fish).
  • UV protection.
• Dry AMD (Non-neovascular):
  • Observation (early).
  • AREDS2 (intermediate/advanced): Vit C (500mg), E (400IU), Lutein (10mg), Zeaxanthin (2mg), Zinc (80mg), Copper (2mg). 📌 LZ-CEZ (Lutein, Zeaxanthin, Vit C, Vit E, Zinc).
• Wet AMD (Neovascular):

  ⭐ Intravitreal anti-VEGF injections (e.g., Ranibizumab, Bevacizumab, Aflibercept) are the mainstay of treatment for neovascular (wet) AMD.

  • Photodynamic Therapy (PDT) with Verteporfin: Adjunctive, specific cases (e.g., PCV).
  • Thermal Laser: Rare, extrafoveal CNVM.
• Low Vision Rehabilitation: Essential for advanced AMD.

High‑Yield Points - ⚡ Biggest Takeaways

• AMD is a leading cause of irreversible vision loss in individuals >50 years.
• Dry AMD: Characterized by Drusen (yellow deposits) and geographic atrophy. More common.
• Wet AMD: Involves Choroidal Neovascularization (CNV), leading to exudation and hemorrhage. More severe.
• Metamorphopsia (distorted vision) is a key symptom, detected by Amsler grid.
• Anti-VEGF injections are first-line treatment for Wet AMD.
• Major risk factors: Age, smoking, positive family history, hypertension.