A blackness in front of the upright eyes after squatting or lying down is called a transient blackout, which may be due to postural hypotension causing transient cerebral hypoperfusion. If severe cerebral insufficiency occurs, a common cause is a thrombus in the carotid system or a blockage in the posterior cerebral artery. In addition to blackness in front of the eyes, blurred vision may also occur, a condition that may be a precursor to stroke disease. If there is also weakness of the limbs, numbness of the deviated body or distorted eyes and mouth, you should promptly go to the hospital for cranial CT or cranial MRI to further clarify the diagnosis and provide symptomatic treatment. It is also necessary to check the intracranial vascular MRI and carotid ultrasound to further clarify the diagnosis and take thrombolytic or anticoagulant treatment if necessary, as well as to check blood sugar, lipids and blood pressure. Patients should maintain a healthy lifestyle, eat a low-salt, low-fat diet, avoid fatty, sweet and greasy foods, and stop smoking and limit alcohol.