Corneal Ulcer (Infectious Keratitis)
NEET PG / Board Examination Essentials
1. Pathophysiology
A corneal ulcer is a breach in the corneal epithelium with underlying stromal involvement/necrosis, typically secondary to an infectious process.
2. Etiological Classification
| Organism | Clinical Clue |
|---|---|
| Bacterial | Purulent discharge, rapid progression, and infiltrates. (e.g., Pseudomonas – aggressive, green discharge). |
| Fungal | Vegetative trauma, indolent course, satellite lesions, feathery edges. |
| Viral | HSV: Dendritic ulcer (fluorescein stain shows branching pattern). |
| Acanthamoeba | Contact lens wear, severe pain (out of proportion to signs), ring infiltrate. |
3. Clinical Presentation
- Symptoms: Pain, photophobia, blurred vision, redness, foreign body sensation.
- Signs: Epithelial defect (stains with fluorescein), stromal infiltrate, conjunctival injection, anterior chamber reaction (possible hypopyon).
4. Management & Pearls
- Diagnosis: Corneal scrapings for Gram stain, KOH prep, and culture/sensitivity.
- Treatment: Intensive topical antibiotics (fortified). Cycloplegics for pain/ciliary spasm.
- Crucial Rule: Never apply topical steroids to an infectious corneal ulcer (risk of worsening the infection/perforation).
- Complications: Corneal scarring, descemetocele, corneal perforation, and endophthalmitis.