Mycotic (Fungal) Corneal Ulcer
Ophthalmology High-Yield Essentials for Board Exams
1. Pathogenesis & Risk Factors
Fungal keratitis is characterized by an indolent course and is strongly associated with vegetative trauma (e.g., injury from plant matter, sticks, or soil).
- Filamentous Fungi (e.g., Aspergillus, Fusarium): Commonly linked to outdoor/vegetative injuries.
- Yeasts (e.g., Candida): Often associated with pre-existing ocular surface disease, dry eye, or contact lens wear.
2. Clinical Features
Fungal ulcers typically progress more slowly than bacterial ulcers.
- Satellite lesions: Small, separate infiltrates surrounding the main ulcer.
- Surface characteristics: The ulcer often appears “dry” or “feathery” with elevated, irregular margins.
- Stromal appearance: Dense, grayish-white infiltration.
- Inflammation: Less dramatic acute inflammation compared to bacterial keratitis initially.
3. NEET PG High-Yield Pearls
| Topic | Key Examination Pearl |
|---|---|
| Diagnostic Test | KOH preparation (to visualize hyphae) and culture on Sabouraud’s Dextrose Agar. |
| Treatment | Natamycin is the drug of choice for filamentous fungi. Voriconazole is indicated for deep stromal infections. |
| Steroids | ABSOLUTELY CONTRAINDICATED as they promote rapid fungal proliferation and increase the risk of corneal perforation. |