Optic Neuritis in Chronic Myeloid Leukemia: A Rare Case Report in Surabaya, Indonesia

Introduction: Chronic Myeloid Leukemia (CML) is a type of myeloproliferative neoplasm in which granulocytes are the primary proliferating cells. Unilateral optic neuritis is another very rare complication of CML, with eye symptoms only consisting of 5% of CML patients. Additionally, optic neuritis in the population aged more than 50 years old is not prevalent and often manifests bilaterally. Case: A 65-year-old female presented with the main complaint of blurred right vision without any prior disease. The ocular examination revealed deteriorated visual acuity in both eyes. Ishihara test yielded 0/38 on the right eye. Complete blood count showed leukocytes 57,57 x 10³/uL, hemoglobin 12,4 g/dL, and platelet 344 x 10³/uL. Bone marrow aspiration showed hyperplasia of erythropoiesis, megakaryopoiesis, and granulopoiesis lineage with myeloblasts at 13%, concluded as an accelerated phase of CML. A qualitative study of chromosomal breakpoints p210 BCR-ABL was positive. Optical coherence tomography presented a thickening macula on the right ocular. Perimetry with the Humphreys test yielded scotoma in the right eye. Magnetic Resonance Imaging suggested a T2 patchy hyperintensity on both optic nerves. The visual acuity and color blindness resolved after three weeks of Imatinib treatment. Discussion: Optic neuritis is one of the rare complications in CML cases. The main mechanisms underlying visual disturbance in CML are hyperleukocytosis, leukemic cell infiltration, or therapy related, while the other possibility related to optic neuritis must be excluded. CML-related visual disturbance is diagnosed with increased leukocytes, myeloblasts in peripheral blood and bone marrow smear, abnormal visual function examination, and neuroimaging. Determining the underlying mechanism that led to optic neuritis is necessary to establish the treatment regimen. While most cases were due to hyperleukocytosis, this case was more likely due to infiltration. The patient’s vision improved after Imatinib treatment for three weeks. Conclusion: Optic neuritis, despite its rarity, could become a complication in a CML patient. An appropriate early diagnosis and treatment are necessary for a favorable outcome.