Acute lymphoblastic leukemia is the most common childhood malignancy. Despite many advances in therapy, about 15%-20% of children with acute lymphoblastic leukemia experience a disease relapse. Isolated ocular relapse is relatively rare. A 14-year-old male with T-cell acute lymphoblastic leukemia in remission presented with sudden onset of right eye pain and visual acuity impairment. Fundoscopic examination of the eye and magnetic resonance imaging of the orbits were consistent with optic nerve infiltration. The patient was treated with salvage chemotherapy, orbital radiation and eventual bone marrow transplantation, with notable improvement in vision and regression of retinal and optic nerve findings. Optic nerve infiltration represents an ophthalmic emergency and requires urgent management. The use of radiation therapy is a helpful adjunct with systemic chemotherapy in obtaining disease remission.