Purpose@#We report two cases of non-arteritic ischemic optic neuropathy (NAION) following extracorporeal membrane oxygenation (ECMO) treatment.Case summary: (Case 1) A 36-year-old man underwent ECMO treatment. Upon regaining consciousness, he complained of a darkened peripheral visual field and was subsequently referred to an ophthalmologist. His best-corrected visual acuity was 0.9 in the right eye and 0.8 in the left eye. The intraocular pressure measured 12 mmHg in the right eye and 10 mmHg in the left eye; color vision was normal. A visual field test demonstrated concentric visual field defects in both eyes, and a fundus examination revealed a pale optic disc. Optical coherence tomography (OCT) indicated a decrease in retinal nerve fiber layer (RNFL) thickness. (Case 2) A 48-year-old woman underwent ECMO treatment. After regaining consciousness, she reported decreased vision in her right eye. Her best-corrected visual acuity was limited to hand motion in the right eye and was 1.2 in the left eye. A relative afferent pupillary defect in the right eye was observed. Color vision in the right eye was compromised, and a fundus examination revealed a pale optic disc. A visual field test demonstrated total visual field defect in the right eye, while OCT showed decreases in both the RNFL thickness and the ganglion cell-inner plexiform layer thickness of the right eye. Magnetic resonance imaging (MRI) revealed high signal intensity and abnormal enhancement in the right retrobulbar optic nerve. @*Conclusions@#In cases where vision loss and visual field defects are observed following ECMO treatment, differential diagnoses for ischemic optic neuropathy are warranted.