The direct communication between the carotid artery and the cavernous sinus is called carotid cavernous fistula (CCF), which is a relatively common neuro-ophthalmological syndrome. Due to special anatomical reasons, the cavernous sinus area is the site with the most arteriovenous fistulas in the body. More than 80% of patients first experience eye symptoms and signs, such as proptosis, congestion, and ocular motility disorders, and then visit an ophthalmologist. Sometimes due to lack of experience, it is misdiagnosed as an inflammatory pseudotumor, thyroid-related eye disease, conjunctivitis, scleritis, etc., which delays treatment and should attract special attention from ophthalmologists. Carotid cavernous fistula is a general name. Any branch of the common carotid artery, including the internal carotid artery, the external carotid artery, and the small blood vessels branching out from it, that directly or indirectly communicates with the cavernous sinus can be called a carotid cavernous fistula.