Carotid cavernous fistula: ophthalmological implications

Carotid cavernous fistula (CCF) is an abnormal communication between the cavernous sinus and the carotid arterial system. A CCF can be due to a direct connection between the cavernous segment of the internal carotid artery and the cavernous sinus, or a communication between the cavernous sinus, and one or more meningeal branches of the internal carotid artery, external carotid artery or both. These fistulas may be divided into spontaneous or traumatic in relation to cause and direct or dural in relation to angiographic findings. The dural fistulas usually have low rates of arterial blood flow and may be difficult to diagnose without angiography. Patients with CCF may initially present to an ophthalmologist with decreased vision, conjunctival chemosis, external ophthalmoplegia and proptosis. Patients with CCF may have predisposing causes, which need to be elicited. Radiological features may be helpful in confirming the diagnosis and determining possible intervention. Patients with any associated visual impairment or ocular conditions, such as glaucoma, need to be identified and treated. Based on patient's signs and symptoms, timely intervention is mandatory to prevent morbidity or mortality. The conventional treatments include carotid ligation and embolization, with minimal significant morbidity or mortality. Ophthalmologist may be the first physician to encounter a patient with clinical manifestations of CCF, and this review article should help in understanding the clinical features of CCF, current diagnostic approach, usefulness of the available imaging modalities, possible modes of treatment and expected outcome.