Dark haze is a clinical symptom in which the eyes cannot see or see clearly when seeing objects, and the main manifestation is darkness in front of the eyes, which is mostly in the form of transient dark haze in the clinic. Black haze is often manifested as dizziness, blurred vision, and sudden blindness, which often occurs without warning, and visual field loss often recovers within 5 to 20 minutes. Black haze is mostly caused by transient cerebral ischemia, anemia, low blood pressure, etc. It often indicates occlusion of the ipsilateral internal carotid artery, which is a typical symptom of internal carotid artery disease; it can also be caused by thrombus obstruction in the body. If black haze occurs, it is necessary to consult a doctor in time to diagnose the cause of the disease through funduscopic examination, craniocerebral CT and other means of examination and treatment.