Case Report: Optic nerve infiltration associated with sequential CRVO and CRAO in isolated CNS relapse of AML.

Optic nerve infiltration as the initial manifestation of isolated central nervous system (CNS) relapse in acute myeloid leukemia (AML) has rarely been reported. We present the case of a 70-years-old man with AML in clinical remission who presented with the sudden onset of a visual field defect and vision loss in the left eye. Initially the patient was diagnosed with non-arteritic anterior ischemic optic neuropathy (NAION) at a local hospital based on findings of decreased vision, optic disc edema and an inferior sectoral visual field defect connected to the physiological blind spot in the left eye, the patient subsequently progressed rapidly to no light perception. Fundus examination showed sequential features consistent with central retinal vein occlusion (CRVO) followed by central retinal artery occlusion (CRAO). Magnetic resonance imaging (MRI) demonstrated thickening and enhancement of the left optic nerve with involvement of the intraconal fat. Cerebrospinal fluid (CSF) cytology confirmed leukemic infiltration, while bone marrow aspiration remained negative for malignant cells, establishing a definitive diagnosis of isolated CNS relapse with optic nerve infiltration. Following intrathecal and systemic chemotherapy, leukemic cells were cleared from the CSF, although the left eye remained without light perception. This case describes the previously unreported sequential onset of optic nerve infiltration, CRVO, and subsequent CRAO in AML, highlighting the need for clinicians to recognize such rare ocular manifestations to detect occult leukemia recurrence early. Atypical or unexplained optic neuropathy in AML patients should raise suspicion of leukemic infiltration. Timely performance of CSF cytology and cranial MRI, together with a multidisciplinary diagnostic and therapeutic approach, is essential for improving visual prognosis and survival rate.