A patient with active herpes zoster ophthalmicus develops disciform keratitis 3 weeks after the rash. The mechanism underlying this form of stromal keratitis is:
- A Direct viral cytopathic effect on keratocytes in the mid-stroma
- B Immune-mediated hypersensitivity reaction to viral antigens deposited in the stroma ✓
- C Bacterial superinfection of the stromal lamellae
- D Neurotrophic breakdown of stromal integrity from ciliary nerve damage
Correct answer: B. Immune-mediated hypersensitivity reaction to viral antigens deposited in the stroma
Explanation
Disciform keratitis in VZV ophthalmicus (and HSV) is an immune-mediated process — a Type IV (delayed hypersensitivity) reaction to viral antigens deposited in stromal keratocytes, triggering T-lymphocyte mediated inflammation. This explains why topical steroids are the mainstay of treatment and why it can recur without active viral replication. Stromal neovascularization (ghost vessels or active vessels) indicates the chronicity of the immune response.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.