A 28-year-old contact lens wearer presents with severe eye pain, photophobia, and a ring-shaped stromal infiltrate with an overlying epithelial defect. Corneal sensation is markedly reduced. Confocal microscopy shows cyst-like double-walled structures. The MOST appropriate initial treatment includes:

• A Topical voriconazole and natamycin
• B Topical moxifloxacin and systemic acyclovir
• C Topical polyhexamethylene biguanide (PHMB) and propamidine isethionate ✓
• D Topical prednisolone to reduce ring infiltrate inflammation

Explanation

The clinical picture — contact lens use, severe pain, ring-shaped stromal infiltrate, reduced corneal sensation, and confocal microscopy showing cysts with double-walled appearance — is pathognomonic for Acanthamoeba keratitis. Treatment requires combined cysticidal therapy: polyhexamethylene biguanide (PHMB) 0.02% plus propamidine isethionate (Brolene) 0.1%. The ring infiltrate represents immune ring (Wessely ring) and must NOT be treated with steroids alone. Topical corticosteroids used prematurely worsen the infection dramatically.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.