BACKGROUND: Posterior ischemic optic neuropathy results from ischemia of the retrobulbar aspect of the optic nerve. It presents as acute loss of vision without optic disc swelling. This is rare in children, with only seven cases reported to date. Neuroimaging is frequently used to aid in the diagnosis of acute visual complaints in children; however, none of the cases described to date delineate the neuroimaging findings of this entity in children. METHODS: We retrospectively reviewed the electronic medical record. RESULTS: We describe the MRI findings in a 10-month-old boy with posterior ischemic optic neuropathy after intraophthalmic artery injection of chemotherapy for retinoblastoma. CONCLUSIONS: As targeted therapies for retinoblastoma and other diseases amenable to intravascular treatment delivery are more frequently used, the risk of grave vision-related side effects increases. Posterior ischemic optic neuropathy should be considered in the differential diagnosis of any child presenting with acute loss of vision. Dedicated imaging of the orbits can elucidate specific findings that may aid in the diagnosis of this entity in children.