A 73-year-old woman initially presented to our ophthalmology department with complaint of a red eye with gradual proptosis and mild restricted movement of the right eye who was misdiagnosed with conjunctivitis during 2 months. One week later she returned to the emergency department with a painful, swollen right eye and a high intraocular pressure of 41 mm Hg and limitation of her extraocular muscles in nearly all fields of gaze. As her IOP was high, she was diagnosed as having secondary glaucoma and was prescribed timolol 0.5% (twice a day) and Latanoprost eye drop at night in the right eye. During follow-up, her IOP remained in high level despite maximum medications. Computed tomography scan of the orbit showed an enlarged superior ophthalmic vein (SOV). In view of her persistent elevated IOP despite maximum medications and dilated conjunctival veins, she was advised digital subtraction angiography (DSA) and imaging revealed a carotid cavernous fistula (CCF). The purpose of this article is to describe ophthalmological complaints of CCFs to help ophthalmologist in understanding the clinical features of spontaneous CCF and avoid misdiagnosis.