An Interesting Case of Ocular Nocardiosis Mistaken as a Fungal Corneal Ulcer

Ocular nocardiosis is a rare corneal infection that often mimics fungal keratitis, resulting in diagnostic uncertainty and potential delays in appropriate treatment. We describe the case of a 47-year-old woman from a rural farming community who developed a painful, red eye after agricultural trauma. She had been treated empirically for presumed fungal keratitis with topical natamycin and clotrimazole, along with oral ketoconazole for one month, yet her symptoms progressed. On presentation, her vision was limited to hand movements near the face. Slit-lamp examination revealed a wreath-shaped suppurative stromal and epithelial infiltration with feathery branches of the ulcer and a two-millimetre hypopyon with marked corneal thinning, without satellite lesions. Corneal scrapings were examined using potassium hydroxide (KOH) and Gram stain. The KOH mount showed no fungal filaments, whereas the Gram stain revealed thin, beaded, branching, Gram-positive filaments suggestive of Nocardia species. Antifungal therapy was discontinued, and treatment with topical moxifloxacin and amikacin 2% hourly, bedtime tobramycin ointment, and oral moxifloxacin was initiated. Clinical and symptomatic improvement occurred dramatically within one week, and the ulcer healed over the next month, leaving a faint scar. The best-corrected vision was improved to 6/18 (pinhole). The residual blur was due to astigmatism from corneal irregularity. This report highlights how nocardial keratitis may imitate a fungal corneal ulcer clinically, and stresses that early laboratory confirmation enables targeted antibiotic therapy, preventing irreversible visual loss.