Severe pseudomembranous keratoconjunctivitis with deterioration of eyesight induced by immune checkpoint inhibitors.

Immune checkpoint inhibitors (ICIs) play a significant role in therapy for relapsed or refractory cancers due to their excellent efficacy. ICIs, however, frequently induce immune-related adverse events (irAEs) in various tissues and organs, sometimes leading to severe conditions. Thus, early identification and treatment of irAEs are important. Herein, the authors report two cases of a rare type of irAE, severe keratoconjunctivitis with deterioration of eyesight, induced by ICIs. Characteristically, both cases were accompanied by concurrent severe oral mucositis. The patients were treated successfully with both systemic and topical ophthalmic corticosteroids, resulting in complete remission of severe pseudomembranous conjunctivitis and full recovery of eyesight. ICI-induced keratoconjunctivitis progresses rapidly and can lead to blindness. Thus, prompt diagnosis and treatment are necessary.