Venous obstruction as the cause of retinal/choroidal dysfunction associated with arteriovenous shunts in the cavernous sinus

Objective: To determine the hemodynamic abnormalities that result in visual acuity loss because of retinal or choroidal dysfunction associated with arteriovenous shunts (AVS) that involve the cavernous sinus. Methods: Retrospective study of the records of 250 patients with either a carotid cavernous fistula or dural arteriovenous malformation revealed a total of 10 patients with vision loss secondary to retinopathy (group I) or choroidal effusion (group II). The cerebral angiograms of these 10 patients and 10 additional patients with visual dysfunction due to elevated intraocular pressure (group III) were evaluated to determine whether the three groups could be distinguished by a specific vasculopathic pattern. Particular attention was given to the extent of thrombosis in the ophthalmic venous system and cavernous sinus. Results: There were angiographic signs of severe thrombosis in the ophthalmic vein in nine patients and in the cavernous sinus in seven patients ipsilateral to the retinal or choroidal lesion. In contrast, in group III, severe thrombosis in the ipsilateral ophthalmic vein and in the cavernous sinus occurred in one and two patients, respectively. Closure of the AVS improved the visual acuity in 1 of 4 patients in group I and in 4 of 5 patients in group II, and normalized the intraocular pressure in all patients. Conclusions: Ophthalmic vein thrombosis, rather than arterialization of the venous system or an arterial “steal,” is the principal cause of retinal or choroidal dysfunction associated with AVS to the cavernous sinus. Following AVS closure, visual recovery is more frequent with choroidal effusion or detachment rather than with retinopathy.