## Histopathology of Dry AMD **Key Point:** Drusen are the pathognomonic hallmark of dry age-related macular degeneration, representing focal accumulations of lipid and protein material between the retinal pigment epithelium (RPE) and Bruch's membrane. ## Drusen Composition & Classification Drusen consist of: - Lipid (cholesterol, cholesteryl esters, phospholipids) - Protein (apolipoprotein B, complement components C3, C5, immunoglobulins) - Oxidized lipid products **High-Yield:** Hard drusen are small (<63 μm), discrete, and associated with minimal visual risk; soft drusen (>63 μm) are confluent, poorly demarcated, and carry higher risk of progression to advanced AMD. ## Distinction from Wet AMD | Feature | Dry AMD | Wet AMD | |---------|---------|----------| | **Pathology** | Drusen, RPE atrophy | Choroidal neovascularization | | **Prevalence** | ~85% of AMD cases | ~15% of AMD cases | | **Progression** | Slow, gradual | Rapid, acute | | **Exudates** | Absent | Present (hard exudates, blood) | **Clinical Pearl:** Geographic atrophy (sharply demarcated areas of RPE and photoreceptor loss) represents the end-stage of dry AMD and is associated with progressive central vision loss. [cite:Robbins 10e Ch 29] 
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