The small eye opening is also clinically referred to as a small eye fissure, which can be considered a medulla oblongata lesion. If a patient suddenly develops a small eye, it is generally considered to be a vascular disease of the medulla oblongata, which can be seen as medulla oblongata infarction and medulla oblongata hemorrhage, usually accompanied by numbness of the ipsilateral side and the contralateral limb. The patient’s eye fissure is smaller and the pupil is also found to be smaller. For vascular disease of the medulla oblongata, treatment should be given for the cause of hemorrhage or ischemia. Secondly, the eyes may not open well and the fissure of the eyes may also be caused by a tumor, also known as paraneoplastic syndrome, which is usually a tumor of the respiratory or digestive system. There is no specific solution for paraneoplastic syndrome, but patients can be treated with symptomatic, acupuncture and nerve nutrition.