Patients with sudden onset of blackness before the eyes and fainting need to be considered from the following aspects: The first one to be considered is posterior circulation ischemia, such as ischemia of the occipital lobe, which can lead to blackness before the eyes and fainting episodes. This disease occurs mostly in middle-aged and elderly people, and a cranial MRI can be perfected to aid in the diagnosis. The second disease to be considered is cardiac disorders, such as various malignant arrhythmias or heart valve disease, which may also lead to blackness before the eyes, but the patient is often accompanied by cardiac discomfort, such as breath-holding, pain, and panic, etc. It is recommended to improve the ambulatory electrocardiogram to assist in the diagnosis. Thirdly, the possibility of reflex syncope cannot be excluded. Fourthly, it is necessary to exclude hypoglycemia, hypotension, etc. Therefore, it is recommended that patients should visit the hospital promptly to identify the cause and treat the symptoms.