Some elderly people sometimes inexplicably lose their sight in one eye suddenly, and then get well again after a minute or a few minutes, and some of them even repeat it several times, and some of them also have numbness of half of the body, sudden inactivity of limbs and other phenomena, or even hemiplegia, a few days or a few months after the occurrence of the above situation. The above symptoms are also known as monocular transient blackout, which refers to the sudden and short-lived loss of vision in one eye. Monovision is a type of ischemic retinopathy. The blood supply to the retina comes mainly from the central retinal artery. The latter is the major artery supplying blood to the brain. Since the central retinal artery is the terminal artery, when vasospasm occurs under certain triggers, or when a thrombus embolus blocks it, acute ischemia occurs in the retina, and the patient will experience the transient blackout mentioned above. Inexplicably one eye suddenly blind, after a minute or a few minutes and then well, some also repeated several times, some of them will also be in the above situation after a few days or months after the occurrence of hemianesthesia, limbs suddenly inactivity and other phenomena, or even hemiplegia. At this time, it is necessary to check the blood fat, blood sugar, blood routine, fundus blood vessels, brain CT and other conditions to clarify.