A 38-year-old man presents with progressive loss of central vision and metamorphopsia. Fundoscopy reveals a yellowish subretinal lesion with drusen at the macula. Visual acuity is 6/24. Which investigation is most appropriate to confirm the diagnosis and assess disease severity?

Explanation

## Clinical Scenario Analysis The patient presents with classic features of **age-related macular degeneration (AMD)**: - Progressive central vision loss - Metamorphopsia (distorted vision) - Drusen and subretinal lesions on fundoscopy - Reduced visual acuity ## Investigation of Choice: OCT with Fundus Autofluorescence **Key Point:** OCT is the gold standard for diagnosing and staging AMD because it provides high-resolution cross-sectional imaging of retinal layers and reveals the exact location and extent of macular pathology. **High-Yield:** Fundus autofluorescence (FAF) imaging complements OCT by: - Identifying areas of retinal pigment epithelium (RPE) dysfunction - Detecting geographic atrophy progression - Predicting conversion from dry to wet AMD - Assessing disease activity and prognosis ## Why OCT + FAF Is Superior | Feature | OCT | FAF | B-scan | Perimetry | ERG | |---------|-----|-----|--------|-----------|-----| | **Macular detail** | Excellent | Good | Poor | N/A | N/A | | **Layer-by-layer anatomy** | Yes | No | No | No | No | | **Drusen characterization** | Yes | Yes | No | No | No | | **Choroidal neovascularization** | Excellent | Good | Poor | No | No | | **RPE changes** | Yes | Yes | No | No | No | | **Guides treatment** | Yes | Yes | No | No | No | **Clinical Pearl:** OCT is now the standard imaging modality for AMD diagnosis, monitoring response to anti-VEGF therapy, and detecting complications like choroidal neovascularization (CNV) or geographic atrophy. ## Diagnostic Algorithm ```mermaid flowchart TD A[Suspected AMD on fundoscopy]:::outcome --> B{Confirm diagnosis & assess severity?}:::decision B -->|Yes| C[OCT + Fundus Autofluorescence]:::action C --> D{Dry or Wet AMD?}:::decision D -->|Dry| E[Monitor with FAF & OCT]:::action D -->|Wet/CNV| F[Anti-VEGF therapy]:::action B -->|Assess functional loss| G[Goldmann/Humphrey perimetry]:::action B -->|Assess retinal function| H[ERG]:::action ``` **Mnemonic:** **OCTFAF** = OCT + FAF for AMD diagnosis - **O**ptical coherence tomography - **C**ross-sectional layers - **T**hickness measurement - **F**undus **A**utofluorescence - **F**or disease activity