A 55-year-old HIV-positive man presented with acute vision loss in the right eye and altered mental status. Ophthalmic evaluation revealed light perception vision OD with a right relative afferent pupillary defect, conjunctival chemosis, large mutton-fat keratitic precipitates, and diffuse cream-colored vitreous cells. Magnetic resonance imaging of the brain and orbit with and without contrast with fat saturation showed choroidal thickening OD, multifocal deep periventricular and deep ganglionic enhancing lesions, and a suprasellar mass. Brain biopsy showed diffuse large B-cell lymphoma. Intrathecal chemotherapy with methotrexate and cytarabine and whole brain radiation therapy failed. His mental status deteriorated. He developed pancytopenia, neutropenic fever, and septic shock and subsequently expired under palliative care.