The sudden appearance of large and small eyes means that the fissures of the eyes are not equally large bilaterally. The first is peripheral facial palsy, which is often referred to as “hanging line wind”. In addition to the enlargement of the eye fissures, there is also a shallowing of the elevation lines on the affected side, drooping of the corners of the mouth on the affected side, and cheek puffing and leakage on the affected side. Secondly, patients with central facial palsy will also have a smaller eye fissure, which is commonly seen in Horner’s sign, and the disease is commonly seen in brainstem infarction. Both of these diseases belong to the treatment of neurology, and it is recommended to visit the neurology clinic in a timely manner. Improve the examination of cranial magnetic resonance, identify the cause, and then treat the symptoms. If the above two diseases are ruled out, it is recommended that a prompt outpatient visit to the ophthalmology clinic can be made to find the cause.