A 48-year-old woman with a positive BRCA1 gene mutation was diagnosed with stage 3b high-grade ovarian endometrioid carcinoma. She was treated with adjuvant carboplatin at a dose of 740 mg (AUC 6) in 3-weekly cycles. Five days after her fifth cycle of carboplatin, she awoke with new-onset blurred vision in her left eye. An ophthalmology review showed left-sided disc oedema with normal optic nerve function tests and 6/24 visual acuity. A CT scan of the head and orbits was performed which showed no evidence of metastasis or raised intracranial pressure. An autoimmune screen was performed which did not reveal any explanation for her visual symptoms. Fundus fluorescein angiography showed bilateral intense late disc leakage with no evidence of vasculitis. Her chemotherapy was stopped in view of a radiological and biochemical remission and her visual symptoms were monitored. She was also started on a tapering dose of prednisolone 40 mg daily. Five months after the initial review, she has developed left optic disc atrophy with 6/18 visual acuity, while the right eye remains asymptomatic. The diagnosis was felt to be that of carboplatin-induced unilateral disc oedema, a very rare side effect of this chemotherapy.