Blindness during remission in two patients with acute lymphoblastic leukemia. A possible complication of multimodality therapy

Two patients with acute lymphoblastic leukemia treated on the same protocol became blind during complete remission. Therapy consisted of systemic combination chemotherapy, prophylactic central nervous system irradiation and monthly intrathecal cytosine arabinoside. Eight months after CNS irradiation visual acuity in both patients began to decrease. Meningeal leukemia in the area of the chiasm was suspected but despite additional radiotherapy, steroids and continued intrathecal therapy, both patients were blind within 6 months. Numerous lumbar punctures were negative for leukemic cells. Extensive investigation, including craniotomy in one case, failed to reveal the cause of blindness. Biopsy of the optic nerve in one case was compatible with radiation toxicity. We postulate that potentiation of radiation toxicity to the optic nerves and chiasm by systemic chemotherapy, intrathecal chemotherapy, or both, may have led to blindness. The patients continue in complete hematologic and CNS remission 12 and 29 months after becoming blind.