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A 68-year-old woman presented to the emergency eye clinic with a 3-week history of progressive left eye redness and discomfort unresponsive to topical antibiotics or lubricants, as prescribed by her optometrist. The intraocular pressure (IOP) was raised (26 mm Hg) and was treated with a topical β-blocker. Otherwise, her condition was managed conservatively for presumed viral conjunctivitis.
She self-presented 6 days later with intermittent visual blurring, mild eyelid swelling, and conjunctival chemosis. The IOP remained raised (24 mm Hg). An inflammatory or allergic etiology was suspected; therefore, topical corticosteroids and a prostaglandin analogue were also prescribed.
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C. Refer the patient for urgent neuroimaging
Clinically, the most likely diagnosis is carotid-cavernous fistula (CCF)—an abnormal communication between the carotid artery (or its branches) and the cavernous sinus, causing high-pressure arterial blood flow within the low-pressure veins, sinuses, and cavernous sinus.1,2 Arterialized (“corkscrew”) conjunctival blood vessels are shown in Figure 1. Other features of this case consistent with CCF included raised IOP (due to increased episcleral venous pressure), conjunctival chemosis, and visual blurring. Significant visual loss may occur secondary to traumatic, ischemic, or glaucomatous optic neuropathy.
In 75% of CCF cases there is a direct connection between the intracavernous segment of the internal carotid artery (ICA) and the cavernous sinus, usually due to arterial wall trauma after head injury.3 Acute high-flow symptoms of direct CCFs (commonly used terms) include visual blurring, motility disorders, proptosis, chemosis, and orbital bruits.
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Corresponding Author: Aaron Jamison, MBChB, Tennent Institute of Ophthalmology, Gartnavel General Hospital, 1053 Great Western Rd, Glasgow G12 0YN, United Kingdom (firstname.lastname@example.org).
Published Online: November 19, 2020. doi:10.1001/jamaophthalmol.2020.4062
Conflict of Interest Disclosures: None reported.
Additional Contributions: We thank the patient for granting permission to publish this information.
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