If CPR is successful, observe the pupils on both sides, there will be gradual pupil dilatation to pupil reduction, and finally it can be reduced to about 2.5mm bilaterally, which indicates the success of CPR, and also proves that the means and time of CPR have achieved good results. If CPR is performed through the pupil to determine, for the pupil gradually appear dilated, and accompanied by loss of consciousness, carotid artery can not be touched to beat, no breathing, heartbeat of the patient, quickly give CPR, within 4-6 minutes if CPR is effective, the pupil will be gradually reduced to the normal level, and the pupils of both sides of the direct-to-light reflex, the gradual existence of the indirect-to-light reflex, and the bilateral pupil reflex also will appear. Pupillary reflexes will be gradually sensitized, all of which are changes in the pupils after CPR.