Abemaciclib and lenalidomide presenting with central retinal artery occlusion in a patient with breast cancer and multiple myeloma: a possible treatment-related association.

Central retinal artery occlusion (CRAO) is a vision-threatening vascular emergency that often causes permanent monocular visual loss. We report a woman in her late seventies with metastatic hormone receptor-positive, HER2-negative breast cancer and multiple myeloma who developed sudden, painless right monocular vision loss while receiving long-term abemaciclib and lenalidomide. Funduscopic examination showed diffuse retinal whitening, attenuated retinal arterioles and a cherry-red spot, confirming CRAO. She presented approximately 20 hours after symptom onset, outside the window for hyperacute intervention and severe visual impairment persisted. Evaluation showed severe hypertension and extensive cardiovascular comorbidity but no high-grade carotid stenosis, large-vessel occlusion or definite cardiac embolic source. Abemaciclib and lenalidomide have each been associated predominantly with venous thromboembolism. Given the patient's multiple vascular and malignancy-related risk factors, a treatment-related contribution, including a possible synergistic interaction, cannot be excluded.