RATIONALE: Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by sustained thrombocytosis, which can lead to thrombotic complications including retinal artery occlusion. We report a rare case of recurrent central retinal artery occlusion (CRAO) as the initial manifestation of ET. PATIENT CONCERNS: A 37-year-old female presented with recurrent transient monocular blindness in the right eye, progressing to persistent amaurosis. Ophthalmic examination revealed findings consistent with acute CRAO, accompanied by significantly elevated platelet counts. Emergency treatment for CRAO restored visual acuity from no-light-perception to 0.8 within 1 hour. Optical coherence tomography showed increased diffuse reflectance at the level of the inner nuclear layer consistent with paracentral acute middle maculopathy. Two recurrent CRAO episodes occurred over the following 2 years, with platelet counts persistently elevated. DIAGNOSES: Bone marrow biopsy revealed megakaryocytic hyperplasia, and genetic testing confirmed JAK2 mutation, establishing the diagnosis of ET. INTERVENTIONS: The patient was treated with hydroxyurea and aspirin. OUTCOMES: Following treatment, the patient achieved normalization of platelet levels with no further episodes of amaurosis. However, discontinuation of medication led to recurrent thrombocytosis and a subsequent cerebral infarction. LESSONS: This case highlights that recurrent CRAO in young patients should prompt investigation for underlying hematological disorders such as ET. Early diagnosis, appropriate cytoreductive and antiplatelet therapy, and long-term multidisciplinary follow-up are essential to prevent vision loss and life-threatening thrombotic complications.
Chen et al. (2026) studied this question.