| Objective: We demonstrated three cases of unilateral red eye due to spontaneous indirect carotid-cavernous fistulas. The symptoms and signs presenting on ocular area were varied between these cases, depending on flow velocity and direction.
Methods: Three Case series.
Results: This study included two women and one man. Two cases were elderly and the other one was a woman of 40 years old. All cases had common symptoms such as unilateral eyelid swelling, mild proptosis and corkscrew scleral vessel engorgements. Most cases had normal vision acuity. No case had systemic problem such as blood hypertension or collagen vascular disease. One case had history of spontaneous subconjunctival hemorrhage on the affected eye. Only one case had obvious orbital bruit and she presented merely congestion on nasal part of conjunctiva. All these patients were confirmed by CT scan, showing dilation of superior ophthalmic vein on the affected eye. The cerebral angiography study revealed communication between meningeal branches of internal carotid artery in two cases, compatible with Barrow type B.
Conclusion: In clinical practice, indirect type of C-C fistula should be considered as differential diagnosis of unilateral non-infectious red eye. | 
