We report a case of posterior ischaemic optic neuropathy after cataract extraction. A 74-year-old man underwent uneventful phacoemulsification and posterior chamber intraocular lens implantation in left eye under peribulber anaesthesia. On the first postoperative day, the patient complained of vision loss in the in the left eye with a visual acuity of 1-m finger counting. After complete ocular, fluorescein angiographic, electrophysiological, systemic and laboratory evaluation, the diagnosis of posterior ischaemic optic neuropathy was made. This case highlights that posterior ischaemic optic neuropathy is a rare clinical entity and should be diagnosed only after exclusion of all other causes in differential diagnosis of postoperative visual loss.