Objective: To report a rare presentation of bilateral optic nerve compression from extra-medullary hematopoiesis in beta thalassemia/Hb E disease.
Design: Interventional case report.
Clinical presentation: A 13-year-old Thai girl was reported with slowly progressive bilateral visual loss due to optic neuropathy as a result of compression from extra-medullary hematopoiesis. Computed tomography of orbit and brain revealed a homogeneous enhancing midline soft tissue mass originating from the ethmoid and sphenoid sinuses along with extensive involvement of the skull.
Intervention: Blood transfusion once every month and low-dose radiotherapy to sphenoid and ethmoid bones with some visual improvement.
Conclusion: Extra-medullary hematopoiesis in beta thalassemia can involve paranasal sinuses and cause compressive neuropathy. In patients with beta thalassemia that required multiple blood transfusions with progressive visual loss, ectopic marrow compression of optic nerve should be ruled out.

Keywords: Optic atrophy, Blurred vision, Extramedullary hematopoiesis, Thalassemia