A 35-year-old farmer presents with a corneal ulcer 5 days after a rice husk injury. Slit-lamp shows a dry, elevated, gray-white ulcer with feathery borders and pigmented colonies on the surface. Satellite lesions are present. Potassium hydroxide (KOH) with calcofluor white preparation of corneal scraping will most likely show which organism?

• A Double-walled cysts measuring 10-25 micrometers
• B Broad, non-septate hyphae with 90-degree branching
• C Gram-positive cocci in chains
• D Thin, septate hyphae with acute-angle branching ✓

Explanation

The clinical picture (feathery borders, satellite lesions, pigmented colonies, vegetable matter injury) is classic for filamentous fungal keratitis (Fusarium or Aspergillus). KOH-calcofluor white shows thin, septate hyphae with acute-angle branching. Broad non-septate hyphae suggest mucormycosis. Double-walled cysts indicate Acanthamoeba. Gram-positive cocci in chains suggest Streptococcus.

Reference: AAO BCSC Section 8: External Disease and Cornea, 2023-2024 ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.