May 10, 2010
5 min read

Man referred for chronic red eye

The patient also had chronic headache and new onset of blurry vision and diplopia.

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Mark E. Patron, MD
Mark E. Patron
Andre J. Witkin, MD
Andre J. Witkin

A 71-year-old man was referred to our practice for evaluation of a chronically red left eye for the past 3 months. There was no associated discharge or pain. He also initially noted blurry vision in the left eye while watching a football game 3 months ago. Since that point, he feels the blurry vision has progressively worsened. Two months prior to presentation, he developed binocular diplopia on upgaze, which has persisted. There was no history of trauma.


The patient’s ocular history was significant for open-angle glaucoma in his left eye, which was currently being treated with Xalatan (latanoprost, Pfizer). For the past few months, IOP had been slightly elevated in his left eye.

His medical history included hypertension, mitral valve prolapse, gastroesophageal reflux disease and chronic headache. He was initially evaluated for a headache and a swishing sound in his left ear by neurology 1 year ago. After an extensive evaluation including an MRI, he was diagnosed with hypertension and started on lisinopril, and his headache improved.


On examination, the patient’s best corrected visual acuity was 20/25 in the right eye and 20/40 in the left eye. His pupils were reactive with no afferent pupillary defect. Ocular motility showed mild restriction of upgaze in his left eye. His color vision with Ishihara color plates was full in both eyes, and Hertel exophthalmometry showed 3 mm of relative proptosis of the left eye. His IOPs were 21 mm Hg in the right eye and 28 mm Hg in the left eye.

Figure 1. Left eye: Dilated corkscrew-shaped conjunctival vessels
Figure 1. Left eye: Dilated corkscrew-shaped conjunctival vessels and chemosis.
Images: Nandakumar N, Marx J

Anterior segment examination showed dilated conjunctival vessels in a corkscrew configuration and chemosis in the left eye (Figure 1). The right eye had a normal anterior segment exam.

Posterior segment examination showed drusen in both eyes, mildly tortuous retinal veins in the left eye and healthy-appearing optic nerves. On auscultation, there was an audible bruit heard over the left eye.

What is your diagnosis?

Red eye, chemosis

Our patient presented with a red eye, chemosis, exophthalmos and increased IOP in his left eye.

The differential diagnosis includes vascular lesions such as carotid-cavernous fistulas (direct and indirect), arteriovenous malformations and cavernous sinus thrombosis. Autoimmune and inflammatory processes such as thyroid eye disease, scleritis and orbital pseudotumor can also be considered. Other etiologies, including processes that elevate episcleral venous pressure such as Sturge-Weber, are also in the differential diagnosis. Chronic conjunctivitis and blepharitis, while unlikely, can also be considered.

Differential diagnosis

Carotid-cavernous fistulas (C-C fistulas) are abnormal communications between the internal or external carotid arteries and the cavernous sinus. They can be classified based on velocity of blood flow (high vs. low), anatomy (direct vs. dural) and etiology (traumatic vs. spontaneous). Direct C-C fistulas are connections between the intracavernous portion of the internal carotid artery and the cavernous sinus. They are high-flow fistulas that are commonly caused by a traumatic tear in the arterial wall. On the other hand, dural C-C fistulas are low-flow fistulas that have connections between the meningeal branches of the internal or external carotid arteries and the dural veins. They can occur spontaneously or from hypertension, diabetes or other vascular disorders. Ocular manifestations of C-C fistulas include chemosis, bruit, exophthalmos, corkscrew-shaped conjunctival vessels and glaucoma secondary to elevated episcleral venous pressure. Ocular motility disturbance, optic nerve ischemia and tortuous retinal veins can also be seen.

Most intracranial arteriovenous malformations are congenital and can vary substantially in size. They may manifest as a headache or seizure or have focal neurological symptoms based on their location; however, they are often asymptomatic.

Thyroid eye disease can present in a number of ways, including bilateral proptosis, eyelid retraction, restrictive myopathy resulting in diplopia, lid lag, conjunctival injection and chemosis. Compressive optic neuropathy has been reported in less than 5% of cases, and patients may present with decreased color vision, a relative afferent pupillary defect and/or visual field defects. A CT scan often shows enlargement of the extraocular muscles sparing the tendon.

Orbital pseudotumor may also have a number of different ocular presentations. It is usually a unilateral process that can manifest as proptosis, diplopia, increased IOP, lid erythema and edema, ocular pain and/or lacrimal gland enlargement. A B-scan ultrasonogram of the eye may demonstrate a T-sign and thickening of the sclera. As opposed to thyroid eye disease, a CT scan will show enlargement of both the extraocular muscles and tendons.

Patients with scleritis often present with pain, photophobia and a red eye. Ocular findings may include diffuse or sectoral areas of deep conjunctival injection, tenderness to touch, chemosis, peripheral keratitis, thickened and inflamed posterior sclera, chorioretinal folds, retinal edema and elevated IOP.

Sturge-Weber syndrome may present with dilated tortuous conjunctival and episcleral vessels, increased IOP, heterochromia irides, diffuse choroidal hemangiomas and serous retinal detachments. Extraocular findings include port wine stains, mental retardation and seizures.

Further workup

Further workup included an MRI/MRA, thyroid function tests and gonioscopy. The MRI demonstrated a dural C-C fistula that was better visualized on the MRA (Figure 2). Thyroid function tests were within normal limits. Gonioscopy showed open angles without blood in Schlemm’s canal or neovascularization of the angle.

Figure 2.  MRA with arrow
Figure 2. MRA with arrow demonstrating the cavernous carotid fistula.

Diagnosis and management

Based on the history, examination and radiological findings, a diagnosis of a carotid-cavernous dural fistula was made. Treatment options included observation, conservative medical management with blood pressure control, carotid compression, angiography and endovascular embolization, or neurosurgery. After extensive discussions with several physicians, the patient elected to undergo angiography and endovascular embolization of the fistula.

The criteria for undergoing angiography with endovascular embolization of a C-C fistula include glaucoma, diplopia, intolerable bruit or headache, and severe proptosis causing exposure keratopathy. Risks of the procedure include ischemic or hemorrhagic stroke, occlusion of the superior ophthalmic vein leading to a central retinal vein occlusion, no improvement in proptosis, red eye or high IOP, and reopening of the fistula.

Figure 3. Angiogram and treatment.

Figure 3. Angiogram and treatment.

Figure 3. Angiogram and treatment.

Our patient successfully underwent embolization of the C-C fistula (Figure 3), and we continue to closely follow him postoperatively.


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  • Namrata Nandakumar, MD, and Jeffrey Marx, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; Web site:

  • Edited by Mark E. Patron, MD, and Andre J. Witkin, MD. Drs. Patron and Witkin can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; Web site: