Immune ring is a feature of -: (A) Interstitial keratitis, (B) Fungal corneal ulcer, (C) Bacterial corneal ulcer, (D) Herpes simplex keratitis
Answer is B. A sterile immune ring (yellow line of demarcation)may be present where fungal antigen and host antibodies meet.Its a sign in fungal corneal ulcer Reference:Comprehensive ophthalmology,AK Khurana,6th edition,page no.106