A 22-year-old man was referred to our hospital with complaints of left eye redness and swelling for more than a month. He had no history of nausea or vomiting, but he also complained of mild blurred vision, double vision and occasional headache for more than a week. On further questioning, the patient revealed a history of a trauma. He was involved in a motor vehicle accident and received a head injury that involved basilar skull fractures and resulted in a subarachnoid haemorrhage and epidural haematoma. The patient received conservative treatment and was discharged from a local hospital following the alleviation of symptoms. However, the patient developed symptoms in the left eye 4 months after the injury. These symptoms included blurred vision, swelling, and hyperaemia of the left eye. He denied a history of diabetes and hypertension. There was no history of pneumonia, tuberculosis, or any other infectious diseases. There was also no history of fever, sickness or any surgery. There was no loss of appetite or loss of weight. He was a non-smoker with no allergies to any medications. On examination, the visual acuity and intraocular pressure in the right eye of the patient were 6/5 and 17 mmHg, respectively, and the corresponding values for the left eye were 4/5 and 25 mmHg. On physical examination, there was no eyelid swelling, exophthalmos, ptosis or visual decrease of the right eye, and this eye was almost normal except for slight hyperaemia. Extraocular muscle movement showed no limitation in the right eye. However, the left eye exhibited eyelid swelling, mild ptosis, exophthalmos, chemosis, and corkscrew hyperaemia centred on the cornea. Furthermore, there were some limitations of eye movement, and abduction and elevation of the left eye was − 1, yet movement on adduction and depression were normal. The left anterior chamber was slightly shallow and quiet, but the right anterior chamber was normal. The cornea was clear with intact corneal sensation in both eyes, and there was no relative afferent pupillary defect and no anisocoria noted. The vitreous and lens were clear. Fundus examinations did not show disc swelling, obvious vascular dilatation or tortuosity, cotton wool spots or haemorrhages of either eye. The resident doctor previously doubted the presence of glaucoma, and he was admitted to our hospital. Optical coherence tomography (OCT) and field of vision tests did not reveal any abnormalities. By contrast, the MRI of the periorbital region revealed a broadening of the left superior ophthalmic vein, slight thickening of the left lateral rectus muscle, and an expansion of the left cavernous sinus, yet the right superior ophthalmic vein, extraocular muscles and cavernous sinus were almost normal. These results aroused suspicion of the left CCF, so the patient was transferred to the neurosurgery department. The neurological examination was normal with the exception of a periorbital bruit on the left side. Thus, a tentative diagnosis of a left CCF was made. Surprisingly, cerebral angiography revealed a crevasse in the inner side of the intracavernous segment of the right internal carotid artery, the right cerebrovascular (CVA) filling delay, and arterial blood traversing the intercavernous sinus to reach the contralateral cavern, which resulted in the dilatation of the left ophthalmic vein. Therefore, the patient was ultimately diagnosed with right CCF. Embolization surgery was suggested, but no additional treatment for the eyes was mentioned since most studies show that symptoms in the eyes could be completely relieved after aetiological treatment. Detachable balloon catheter embolization surgery was performed after several days. The surgery was successful, and the patient recovered well. All symptoms, including the redness and swelling of the left eye, the blurred vision, and the double vision, were resolved. On physical examination prior to the patient’s discharge, the visual acuity was improved to 5/5, and the intraocular pressure was 18 mmHg in the left eye, which was within the normal range. Additionally, the exophthalmos, chemosis and hyperaemia of the left eye were significantly relieved.