A 64-year-old woman with relapsed acute myelogenous leukemia (AML) undergoing salvage chemotherapy developed rapid onset of right-sided ophthalmoplegia, proptosis, optic neuropathy, and vision loss from 20/30 to hand motions over a 3-hour period on day 4 of her treatment. CT scan of her orbits revealed a superolateral orbital mass and periocular edema. She underwent immediate canthotomy and cantholysis, and lateral orbitotomy with debulking of the mass later the same day. The histopathology was consistent with aggregates of myeloid blasts. Her vision recovered to 20/20 on postoperative day 1. Orbital granulocytic sarcoma is a rare condition often concurrent with AML, typically in the pediatric population and rarely in adults. Presentation as a fulminant orbitopathy with rapidly progressive optic neuropathy and vision loss over several hours has not been previously reported.