A 40-year-old farmer presents with a corneal ulcer after injury with a vegetable matter. Slit-lamp examination reveals a gray-white infiltrate with feathery margins, satellite lesions, and an endothelial plaque. Smear with KOH mount shows septate hyphae. The most appropriate initial treatment is:

• A Topical natamycin 5% every 1 hour ✓
• B Topical voriconazole 1% every 1 hour
• C Topical fluconazole 0.3% every 2 hours
• D Topical amphotericin B 0.15% with systemic itraconazole

Explanation

The clinical scenario — agricultural/vegetable matter injury, feathery margin infiltrate, satellite lesions, endothelial plaque — is characteristic of filamentous fungal keratitis (typically Fusarium or Aspergillus). The gold-standard first-line topical treatment is natamycin 5% suspension, which is effective against filamentous fungi (Fusarium, Aspergillus) due to its polyene mechanism binding ergosterol. Voriconazole is preferred for Aspergillus and in natamycin-resistant cases. Fluconazole has poor activity against filamentous fungi; amphotericin B is better suited for Candida and Aspergillus.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.