Pupil dilation is caused by damage to the muscles or nerves that control pupil contraction and dilation and can be seen in disease conditions such as cerebral hemorrhage, poisoning, or in cases of trauma resulting in acute massive blood loss. If treatment is not timely, the patient shows signs of pupil dilation that can terminate vital signs within minutes or hours. In addition, it cannot be ruled out that some patients have physiological pupil dilation caused by the application of pupil-dilating medication, and there is no question of how long it takes to die.1. Disease factors: Diseases that cause pupil dilation are usually seen in brain disorders, such as cerebral hemorrhage and cerebral bruising, usually caused by bleeding or bruising from the lesion, which compresses the nerves that control pupil contraction. This is a serious condition, and if not treated promptly, the patient can die within a few hours. If the treatment is timely, the patient’s life can be saved and the pupil dilation can disappear; 2, poisoning: including carbon monoxide poisoning, mandrake poisoning, ephedrine poisoning, etc. Usually when the pupil dilation appears in poisoned patients, it indicates that the toxin has affected the eye nerve, and if the treatment is not timely, death can occur within minutes or hours; 3, trauma: if there is acute massive blood loss, the patient falls into After coma, consciousness is gradually lost, and will lose control of the pupil contraction nerve. If this type of patients show dilated pupils, it usually indicates that they are already at the end of life, and if there is no timely hemostasis and resuscitation, death can occur within a few minutes. If rescued in time, the dilated pupil will gradually return to normal with the recovery of vital signs and the patient’s life will be saved. Dilated pupils are usually one of the criteria for judging vital signs, but it is not possible to judge whether or how soon death will occur based on this single sign. Other clinical indicators used to determine a patient’s vital signs include respiration, pulse, heart rate, blood pressure, and body temperature, etc. A combination of these indicators is needed to assess the patient’s current condition. If a patient’s vital signs are weakening or disappearing in addition to pupil dilation, death may occur within a short period of time if treatment is not timely. If the patient’s pupils are dilated and other signs have disappeared, it often indicates that the patient is already dead and there is no possibility of death for much longer.