Patients squatting for a long time after standing up black in front of the eyes, it may be anemia or the occurrence of postural hypotension, as follows: 1, anemia: patients suspected of anemia, routine blood tests can be determined. 2, postural hypotension: patients suspected of postural hypotension, you can let the patient lying down for more than five minutes, standing for a minute, five minutes when the blood pressure is measured, if the systolic blood pressure drops more than 20mmHg, and accompanied by dizziness and syncope, it is called postural hypotension. Where the patient’s blood pressure is lower than 90/60 mmHg, it is called hypotension. Acute persistent hypotension is most often seen in serious conditions, such as shock, myocardial infarction, acute cardiac compression, etc. Chronic hypotension can also have physical causes, and the patient complains of consistently low blood pressure, usually without symptoms.