Central Corneal Ulcer in a Contact Lens Wearer
A 24-year-old student who wears monthly soft contact lenses, including overnight about 3 nights per week, presents with 24 hours of severe right eye pain, photophobia and discharge. Acuity is 20/200 right and 20/20 left. There is a 2 mm central epithelial defect with a 1.5 mm dense stromal infiltrate, a 0.5 mm hypopyon, marked ciliary flush, and no satellite lesions or ring infiltrate. She rinses her lens case with tap water and last changed lenses 6 weeks ago. The referring clinic started moxifloxacin every hour 6 hours ago. Intraocular pressure is 16 mmHg and B-scan is normal. She is healthy and has no previous ocular surgery. She asks whether patching the eye overnight is helpful.
1. What investigations and empirical antimicrobial treatment would you start, and how do the risk factors change coverage?
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Investigations. Take a corneal scrape before or immediately after starting treatment: Gram stain, Giemsa, blood agar, chocolate agar, Sabouraud agar, and non-nutrient agar with Escherichia coli for Acanthamoeba. Send the contact lens, case, and solution for culture. Do not delay antibiotics for culture results. Confocal microscopy can help if Acanthamoeba is suspected.
Empirical therapy. Overnight wear and tap water exposure raise concern for Pseudomonas and Acanthamoeba. For a 1.5 mm dense infiltrate with hypopyon, start fortified antibiotics: cefazolin 50 mg/mL and tobramycin 14 mg/mL, alternating every 30 minutes around the clock initially. Fluoroquinolone monotherapy (moxifloxacin 0.5% hourly) is an alternative where fortified drops are unavailable, but the hypopyon and severity favor fortified coverage. Add PHMB 0.02% and chlorhexidine 0.02% hourly if there is a ring infiltrate, radial keratoneuritis, pain out of proportion, or no improvement at 48 hours. Consider antifungal therapy for feathery margins or plant trauma.
Supportive care. Do not patch the eye. Remove the lens and discard the case. Treat pain, review daily, and hospitalize if compliance is doubtful or the ulcer is worsening. Check for systemic risk factors.
2. When would you use topical corticosteroids, when would you operate, and how would you follow her?
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Steroids. Topical corticosteroids reduce inflammation and scarring but can promote microbial growth. Use them only after 24–48 hours of effective antimicrobial therapy, when the ulcer is responding, and never when fungal or Acanthamoeba infection is suspected. Do not use steroids just to treat a hypopyon. Start a mild steroid such as prednisolone acetate 1% four times daily and taper slowly under review.
Surgery. Indications include impending or actual perforation, a descemetocele, progressive thinning despite treatment, or a non-healing ulcer. A tectonic or lamellar graft, or penetrating keratoplasty, may be needed. Surgery is not indicated for hypopyon alone, which usually resolves with antibiotics. Therapeutic penetrating keratoplasty in an active infection has a high failure rate, so optimize medical therapy first unless the eye is perforating.
Follow-up. Review daily until the infiltrate shrinks and the epithelium heals, then every 2–3 days and taper antibiotics according to response. Do not restart contact lenses until complete healing and a new lens and case are supplied. Warn her that vision may remain scarred and that she may need a corneal transplant later. Document that overnight wear must stop.