Exophthalmos refers to the protrusion of the eyeball beyond the normal range. The normal protrusion of the eyeball is 12-14mm, with an average of 13mm, and the difference between the two eyes does not exceed 2mm. Exophthalmos can be a sign of eye disease or a symptom of systemic disease. In addition to the lesions in the orbit itself, it is often closely related to diseases in internal medicine, otolaryngology, and neurosurgery oncology. The normal position of the eyeball in the orbit is maintained by the interaction between the tissues in the orbit. For example, the blood vessels and fat in the retrobulbar tissue, the normal tension of the oblique muscle, etc. have a tendency to push the eyeball forward; while the orbital septum and its smooth muscle, the tension of the four rectus muscles, and the medial and lateral canthal ligaments have the effect of preventing the eyeball from protruding forward. All lesions that increase the volume of the orbit, rectus muscle paralysis, and changes in the orbital cavity due to abnormalities of the orbital bone can cause exophthalmos.