Marginal Keratitis
Marginal keratitis is a non-infectious, inflammatory infiltration of the peripheral cornea caused by a hypersensitivity reaction to staphylococcal antigens. It is strongly associated with chronic staphylococcal blepharitis.
📌 About
- Common peripheral corneal inflammatory condition.
- Hypersensitivity reaction rather than direct infection.
- Frequently associated with staphylococcal blepharitis, rosacea, or seborrheic dermatitis.
🧾 Aetiology
- Auto-inflammatory response to staphylococcal antigens from the eyelid margin.
- Blepharitic lids rubbing against the cornea contribute to pathology.
- Chronic lid disease (rosacea, seborrheic dermatitis) increases risk.
👁️ Clinical Features
- Severe eye pain and photophobia.
- Ciliary injection may be seen.
- Examine lids: often crusting, telangiectasia, and meibomian gland dropout.
- Corneal infiltrates near the limbus, usually separated from it by a clear corneal zone.
- Severe cases → corneal ulceration.
🔬 Investigations
- Diagnosis is clinical with slit-lamp exam.
- Findings: stromal infiltrates of peripheral cornea (1–2 mm from limbus).
- History of recurrent blepharitis is common.
🚩 Red Flags (Consider Other Pathology)
- Large epithelial defect (>1 mm).
- Dense corneal infiltrate.
- Dendritic or geographic ulcer → suspect HSV.
- Peripheral corneal thinning or melt.
- Reduced corneal sensation.
- Anterior chamber inflammation.
- Contact lens wear, history of cold sores, or systemic autoimmune disease.
🛠️ Management
- Topical corticosteroids (e.g. dexamethasone) short course for inflammation (≈ 1 week).
- Lid hygiene (warm compresses, lid cleaning, treating blepharitis) to reduce recurrences.
- Oral antibiotics for recurrent blepharitis: doxycycline (avoid in pregnancy/children) or erythromycin.
- Refer to ophthalmology if red flags present, atypical course, or poor response to therapy.
📚 References
