Direct traumatic carotid–cavernous fistula with compressive optic neuropathy following blunt orbital trauma in a young female

A carotid cavernous fistula (CCF) is an anomalous connection between the cavernous sinus and the carotid artery system.[1] They may occur spontaneously or, more commonly, following trauma. They are frequently brought on by a single traumatic rupture in the internal carotid artery (ICA) cavernous section, which causes the ICA and cavernous sinus to communicate directly.[2] Traumatic CCFs are typically high-flow and direct, causing orbital congestion, proptosis, chemosis, and cranial nerve palsies. If untreated, they may lead to vision loss. We report a rare case of direct CCF with compressive optic neuropathy after blunt orbital trauma in a young female. A 22-year-old female presented with progressive redness, swelling, and decreased vision in the left eye, three weeks postblunt trauma. Visual acuity was 6/9 in the right eye and 6/36 in the left, with Grade 3 relative afferent pupillary defect (RAPD) (Bell’s grading). Color vision was reduced in the left eye on Ishihara testing. The anterior segment examination showed marked conjunctival chemosis and congestion with corkscrew-like dilated and tortuous episcleral vessels in the left eye [Figure 1a]. Hertel’s exophthalmometry showed 24-mm proptosis in the left eye, and the intraocular pressure (IOP) was 30 mmHg in the left eye. Ocular motility assessment demonstrated left eye lateral gaze restriction [Figure 2]. Posterior segment examination of the left eye revealed venous tortuosity. Auscultation over the left eye revealed an ocular bruit. MRI of the brain and orbits showed features consistent with a direct left-sided carotid–cavernous fistula: left-sided proptosis, dilated superior ophthalmic vein [Figure 1b white arrow], with a flow void appearance, indicating high-velocity blood flow. The diagnosis of carotid–cavernous fistula in the left eye was made and started with oral acetazolamide, tear supplements, and neurosurgical consultation was obtained. The patient was advised for endovascular embolization, which is the standard treatment for direct traumatic CCF.Figure 1: Anterior segment photograph of the left eye showing marked conjunctival congestion with corkscrew episcleral vessels (a), while T2-weighted sagittal magnetic resonance imaging of the brain and orbit (b) showing left-sided proptosis and a dilated superior ophthalmic vein with a flow void appearance, indicating high-velocity blood flowFigure 2: Nine-gaze photographs showing left eye lateral gaze restrictionDirect carotid–cavernous fistulas are usually traumatic and involve high-flow shunts between the ICA and cavernous sinus, most commonly due to basal skull fractures causing ICA tears (70%–90%).[3,4] CCFs raise orbital venous pressure, causing chemosis, proptosis, ocular bruit, cranial nerve palsies, and elevated IOP due to increased episcleral venous pressure.[5] Elevated IOP and secondary glaucoma can be caused by increased vortex venous pressure and episcleral pressure.[6,7] Compressive optic neuropathy, although less common, may result from venous congestion and elevated intraorbital pressure compromising the optic nerve head perfusion. This case shows classic signs, including conjunctival chemosis, corkscrew episcleral vessels, ophthalmoplegia, elevated IOP, and RAPD, indicating compressive optic nerve involvement. MRI and angiography are key for diagnosis, and endovascular embolization is the preferred treatment, offering rapid improvement. Direct traumatic carotid–cavernous fistula is a vision-threatening complication of orbital trauma, and early recognition is crucial. This case highlights CCF presenting with compressive optic neuropathy and elevated IOP following blunt trauma. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed. Data availability statement Data will be made available on reasonable request to the corresponding authors. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.