A 52-year-old farmer from rural Maharashtra presents with a 5-day history of painful left eye with photophobia and foreign body sensation. He reports a thorn prick injury while working in the field 2 weeks ago. On examination, visual acuity is 6/36, and slit-lamp shows a central corneal infiltrate with feathery margins and satellite lesions. KOH mount of corneal scrapings reveals septate hyphae. What is the most appropriate initial management?

Explanation

## Fungal Corneal Ulcer — Diagnosis and Management ### Clinical Presentation The patient presents with classic features of fungal keratitis: - **Risk factor:** Agricultural trauma (thorn prick) — organic material inoculation - **Timeline:** Indolent course over 2 weeks (slower than bacterial) - **Morphology:** Feathery infiltrate margins with satellite lesions — pathognomonic for fungal infection - **KOH mount finding:** Septate hyphae confirms filamentous fungal infection (likely *Aspergillus* or *Fusarium*) ### Correct Management: Topical Natamycin + Oral Fluconazole **Key Point:** Natamycin is the gold-standard topical antifungal for corneal ulcer because it: - Achieves high corneal penetration without systemic absorption - Has broad-spectrum coverage (Aspergillus, Candida, Fusarium) - Avoids systemic toxicity - Dosing: Every 1–2 hours initially (6 times daily minimum) **Clinical Pearl:** Oral fluconazole is added as adjunctive therapy because: - Provides systemic antifungal cover - Achieves therapeutic aqueous humor levels - Reduces risk of dissemination or recurrence - Particularly important in immunocompromised patients or deep stromal involvement **High-Yield:** Fungal keratitis often requires prolonged treatment (4–6 weeks) and close monitoring for perforation risk. ### Differential Antifungal Agents | Agent | Route | Indication | Limitation | |-------|-------|-----------|------------| | **Natamycin** | Topical | First-line for filamentous fungi | Polyene; poor aqueous penetration | | **Fluconazole** | Oral/IV | Adjunctive; Candida | Azole; good penetration | | **Itraconazole** | Oral | Alternative for Aspergillus | Erratic absorption; hepatotoxicity | | **Amphotericin B** | Systemic | Severe/disseminated disease | Nephrotoxic; reserved for resistant cases | | **Miconazole** | Topical | Rarely used alone | Inferior corneal penetration | **Warning:** Topical corticosteroids are contraindicated in fungal keratitis — they promote fungal proliferation and risk perforation. [cite:Khurana & Khurana Textbook of Ophthalmology Ch 5]