A 9-year-old boy with vernal keratoconjunctivitis has a large horizontal corneal ulcer in the upper half of the cornea that fails to heal despite intensive lubricants. Histology of the base shows deposited eosinophil granule protein. The factor chiefly responsible for persistence of this ulcer is:

• A Secondary invasion by Candida albicans
• B Collagenase secreted by invading neutrophils
• C Direct toxic effect of preserved topical drops
• D Major basic protein released by eosinophils ✓

Explanation

Shield ulcer of vernal keratoconjunctivitis persists because eosinophil major basic protein deposits in the epithelial basement membrane zone and inhibits re-epithelialisation, compounded by mechanical rubbing from giant tarsal papillae. Neutrophil collagenase drives melting in infective ulcers, not this allergic shield ulcer.

Reference: Kanski's Clinical Ophthalmology, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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