Acanthamoeba keratitis is classically associated with contact lens use. The MOST characteristic early clinical sign that helps distinguish it from fungal or herpes simplex keratitis is:

• A Dendritic ulcer with terminal bulbs on fluorescein staining
• B Feathery margins with satellite lesions extending into the stroma
• C Hypopyon with anterior staphyloma formation
• D Severe, disproportionate pain (out of proportion to clinical signs) with perineural infiltrates (radial keratoneuritis) ✓

Explanation

Acanthamoeba keratitis characteristically causes severe, disproportionate pain relative to the initial clinical findings — attributed to perineural invasion. The pathognomonic early finding is radial keratoneuritis — infiltrates along corneal nerves (perineural infiltrates) appearing as radially-oriented white lines on slit-lamp biomicroscopy. Dendritic ulcer with terminal bulbs is pathognomonic of herpes simplex keratitis. Feathery margins with satellite lesions are characteristic of fungal (Aspergillus/Fusarium) keratitis. Hypopyon with anterior staphyloma is a late complication of severe bacterial keratitis.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.