PURPOSE: The purpose of this study is to report a case of corneal perforation in a patient with undiagnosed keratoconus and underlying rheumatoid arthritis.METHODS: This is a retrospective case study based on the patient's medical records and followed by a brief review of the literature.RESULTS: A 53-year-old patient was referred to our department for acute pain and sudden decrease of visual acuity in his left eye. Corneal perforation was detected and attributed to a previously undiagnosed and untreated keratoconus. Additional laboratory work-up and clinical examination revealed a coexisting rheumatoid arthritis. Amniotic membrane was originally transplanted in order to maintain the structural integrity and promote healing of the perforated eye. Subsequently, the patient underwent a penetrating keratoplasty, though with unfavorable results due to postoperative endophthalmitis.CONCLUSIONS: Rheumatoid arthritis may be associated with higher risk of corneal perforation in patients with ectatic degenerative diseases such as keratoconus.