The presenting complaint of unilateral blurred vision in a young female patient was due to a branch retinal artery occlusion by an ophthalmoscopically visible embolus. After medical evaluation she was discovered to have a homolateral cervical carotid artery aneurysm. One of the complications of an aneurysm is thrombosis with subsequent embolization of fragments of the thrombus. This source of retinal emboli has not previously been documented.
McEntyre JM, Keates EU, Whiteley WH. Retinal Embolus From Extracranial Carotid Artery Aneurysm. Arch Ophthalmol. 1967;77(3):317-319. doi:10.1001/archopht.1967.00980020319005