Retinal arterial macroaneurysm rupture caused by dissection-like change in the vessel wall

PURPOSE: To highlight a potential pathogenetic mechanism of retinal arterial macroaneurysm. OBSERVATIONS: A 79-year-old woman presented with a ruptured retinal arterial macroaneurysm in the right eye. One year after treatment, high-resolution multimodal imaging with optical coherence tomography (OCT), OCT angiography, and adaptive optics scanning light ophthalmoscope showed that a narrow passage developed in the vessel wall of the pre-existing retinal arterial macroaneurysm and another macroaneurysm had developed adjacent to the pre-existing one. CONCLUSIONS AND IMPORTANCE: These images suggest the pathogenesis of retinal arterial macroaneurysm (RAM) associated with crack-like changes in the retinal arterial wall, similar to pathologies seen in systemic arteries.