A male in his 70s presented with progressive vision loss in his right eye for 2 months. The conjunctival vessels in both eyes appeared dark red, excessively dilated, and tortuous. Macular optical coherence tomography revealed macular edema in the right eye. A cerebral angiogram demonstrated the presence of a left carotid cavernous fistula. The patient was diagnosed with macular edema and tortuous conjunctival vessels secondary to a carotid cavernous fistula. Subsequently, the patient underwent endovascular interventional embolization of the fistula, resulting in complete occlusion of the fistula. At the 1-month follow-up, the patient reported that the redness in his eyes had disappeared and his vision had improved.