A woman in her 30s with no significant medical history presented with a 1-month history of worsening “bulging,” redness, and mild pain in her right eye. She also reported intermittent, binocular diplopia. Results from a review of systems were otherwise negative, and she had not experienced recent trauma. She was started on topical antihypertensive drugs for elevated intraocular pressure (IOP) in the affected eye (30 mm Hg) and referred to our institution. On examination, visual acuity was 20/20 in both eyes with subjective red desaturation OD. Pupils were equal and without afferent pupillary defect. Confrontation visual fields were full. Intraocular pressures were 24 mm Hg OD and 12 mm Hg OS. Hertel exophthalmometry showed 4.5 mm of relative proptosis OD. She had limitation of her extraocular muscles in nearly all fields of gaze OD, with the most obvious limitation occurring in abduction. She had decreased sensation to light touch in the right cheek (cranial nerve V2). There were no orbital bruits. Ocular examination revealed diffuse conjunctival injection OD with tortuous, dilated, corkscrew-shaped blood vessels (Figure, A). Dilated fundus examination revealed mild optic nerve hyperemia and mild vascular tortuosity OD. Vital signs and results from complete blood cell count and thyroid function tests were normal. Computed tomography and magnetic resonance imaging, angiography, and venography of the brain and orbits revealed extraocular muscle enlargement and enhancement and a dilated superior ophthalmic vein OD. There was no mass, abscess, or arteriovenous fistula (Figure, B).