## Fungal Corneal Ulcer — Key Characteristics **Key Point:** Fungal corneal ulcers are notoriously slow-growing, indolent infections that progress over days to weeks, NOT hours. This is a critical distinguishing feature from bacterial ulcers. ### Clinical Course & Progression | Feature | Bacterial Ulcer | Fungal Ulcer | |---------|-----------------|---------------| | **Onset** | Acute (24–48 hrs) | Insidious (days to weeks) | | **Progression** | Rapid, may perforate in 48–72 hrs | Slow, indolent; perforation rare unless neglected | | **Margin** | Sharp, well-demarcated | Feathery, with satellite lesions | | **Stromal involvement** | May be rapid | Deep stromal invasion common | | **Hypopyon** | Common, may be large | Present but often less prominent | ### Management & Drug Choice **High-Yield:** Natamycin (pimaricin) 5% is the **first-line topical antifungal** for filamentous fungi (Aspergillus, Fusarium). Amphotericin B is reserved for Candida or when natamycin fails. **Clinical Pearl:** Fungal ulcers are often misdiagnosed as bacterial initially because they respond poorly to antibiotics. The key clinical clue is the **indolent course over 1–2 weeks** with minimal discharge and a feathery, irregular margin. ### Epidemiology & Risk Factors - **Filamentous fungi** (Aspergillus, Fusarium): agricultural trauma, plant material contact - **Candida species**: immunocompromised (HIV, diabetes, prolonged topical steroids) - **Geographic variation**: tropical and subtropical regions (India, Africa) **Warning:** Topical corticosteroids accelerate fungal ulcer progression and are contraindicated until the infection is controlled. ### Why Option 1 Is Incorrect Fungal corneal ulcers progress **slowly over days to weeks**, not rapidly with perforation in 48 hours. Rapid perforation is characteristic of aggressive bacterial ulcers (especially Pseudomonas). This slow progression is why fungal ulcers are often missed on initial presentation.
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