Unilateral optic nerve leukemic infiltration due to relapse in a case of acute lymphoblastic leukaemia

A 35-year-old male presented with a sudden onset painless loss of vision in the left eye (LE). He was a known case of T-cell acute lymphoblastic leukaemia and had achieved complete remission following chemotherapy. The vision was reduced to absent light perception in LE. Fundus examination in LE revealed disc edema and retinal haemorrhages. Magnetic resonance imaging of the brain and orbits showed subtle enhancement of the left optic nerve. The cerebrospinal fluid study did not reveal any malignant cells. The patient was advised to undergo orbital radiotherapy, which he refused. There was further systemic and ocular worsening two months following the initial presentation. Early diagnosis and prompt intervention are crucial in salvaging eyes with leukemic optic nerve infiltration.