An object of the present invention is to provide a new medicinal use of 2-phenyl-1,2-benzisoselenazol-3(2H)-one or a salt thereof. 2-Phenyl-1,2-benzisoselenazol-3(2H)-one or a salt thereof exhibits an excellent prevention and improvement effect in corneal disorder models, and is therefore useful as a preventive or therapeutic agent for a keratoconjunctival disorder such as dry eye, superficial punctate keratopathy, corneal epithelial defects, corneal erosion, corneal ulcer, conjunctival epithelial defects, keratoconjunctivitis sicca, superior limbic keratoconjunctivitis, filamentary keratoconjunctivitis, keratitis or conjunctivitis.
