Sudden black eye for a second or two and then recover refers to a transient black eye symptoms, the cause of the disease and physiological factors and pathological factors are related. 1. Physiological factors: from a systemic point of view, if the patient is in a state of fatigue for a long time, the physical energy will produce excessive consumption, if there is hypoglycemia or suddenly get up and have low blood pressure, which can lead to the patient to appear transient darkness in front of the eyes symptoms. 2. Pathological factors: for patients with carotid artery blood flow pathology for a long time, it is very easy to affect the blood circulation of the eye, and then bring harm to the patient’s retinal health, which can lead to retinal vascular sclerosis, the patient can have transient retinal ischemia, which can lead to the symptom of sudden darkening of the eyes. It is recommended that patients who experience frequent darkening of the eyes should consult a doctor in time to assess their condition and follow the doctor’s instructions for treatment.