1, vasospasm: it is mostly caused by vascular motor nerve dysfunction or hypertension, and there may be short-term visual impairment or migraine before onset.

2, thrombosis: arteriosclerosis, stenosis or intravascular inflammation, the inner wall of blood vessels is rough, which is easy to lead to thrombosis, leading to blood flow interruption.

3. Arterial embolism: when endocarditis or atherosclerosis occurs, the hardened plaque falls off, or the cardiac vegetation falls off to form an embolus, which flows to the central retinal artery to cause embolism.