A 12-year-old boy with severe vernal keratoconjunctivitis develops a large transverse oval epithelial defect in the upper half of the cornea with a plaque of mucus at its base. The principal factor maintaining this defect is:
- A Toxic effect of eosinophil granule proteins deposited on the cornea ✓
- B Direct mechanical abrasion by the tarsal conjunctival papillae
- C Secondary bacterial colonisation by Staphylococcus epidermidis
- D Tear film deficiency from goblet cell loss
Correct answer: A. Toxic effect of eosinophil granule proteins deposited on the cornea
Explanation
The shield ulcer of vernal keratoconjunctivitis persists because of toxic mediators released from degranulated eosinophils, particularly major basic protein, which inhibit epithelial migration and healing over the upper cornea. Mechanical rubbing contributes to initiation but the biochemical toxicity sustains the plaque and defect. Treatment combines debridement of the plaque with topical steroids and mast cell stabilisers rather than antibiotics alone.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.