Sudden onset of transient blackout in one eye is a clinical condition in which the eye is unable to see or see clearly when looking at an object, and is characterized by blackness in front of the eyes. The clinical condition is mostly in the form of transient blackout, often due to transient cerebral ischemia, also known as transient cerebral ischemia. 1. Stroke aura Usually refers to the blockage of blood vessels in the anterior circulation of the brain, i.e., thrombosis of the internal carotid artery system, including the common thrombosis of the middle cerebral artery and thrombosis of the anterior artery, with the typical symptoms of weakness of partial body movement, numbness, and distortion of the mouth and eyes. In contrast, patients with thrombosis of the posterior circulation artery, dizziness, blurred vision, sudden double vision, and short time recovery are vascular embolism of the posterior circulation of the brain. 2. Transient black clouding is a typical symptom of internal carotid artery lesion. The onset of this symptom is often without any aura and often without any precipitating factors. Patients experience a sudden onset of painless vision loss in one eye. The loss of vision peaks within seconds and quickly encompasses the entire visual field, which is completely black or gray. Transient black haze is often seen clinically as a harbinger of carotid artery disease, and can be predicted to have carotid artery disease in 70% to 97% of patients with transient black haze.