Impression cytology
CONJUNCTIVA
CIC was performed at least 15 min after all ocular examinations. Polyethersulfone filters (Supor 200 membrane; Pall Corporation, Port Washington, NY, USA) were applied to the superotemporal nonexposed bulbar conjunctiva after halving (13 mm × 6.5 mm). The samples were used for periodic acid–Schiff (PAS) staining.