A 72-year-old female presented to the Wills Eye Emergency Room complaining that her left eye was “bulging out” for two days, and that her eyelids were swollen. The bulging began suddenly and was initially painful, awakening the patient from sleep. She reported blurred vision in the left eye and intermittent, binocular diplopia that was not present at the time of presentation. The patient had undergone imaging at an outside hospital and was told to come to Wills because of “a tumor behind my eye.”

Medical History
The patient had a medical history significant for cardiovascular disease requiring seven stenting procedures and gastroesophageal reflux disease. Her medications included omeprazole, atenolol, isosorbide mononitrate, rosuvastatin, lisinopril, aspirin and clopidogrel. Review of systems was positive for recent gastrointestinal illness. The patient denied a history of malignancy and had recently undergone a mammogram, which was negative.

Best-corrected visual acuity was 20/25 in the right eye and 20/50 in the left eye with no pinhole improvement. Pupillary examination was normal with no relative afferent pupillary defect. Extraocular motility was normal in the right eye; however, upgaze in the left eye was restricted to 60 percent of normal. Confrontation visual fields were full in both eyes. The patient identified nine out of nine Ishihara color plates in each eye. By Hertel exophthalmometry, she had 3 mm of left-sided proptosis. Intraocular pressure measured 11 mmHg in each eye. Anterior examination revealed a small area of temporal subconjunctival hemorrhage in the left eye, and minimal left adnexal ecchymosis and edema (See Figure 1). Cortical and nuclear cataracts were present in both eyes. Posterior examination was normal in both eyes except for bilateral posterior vitreous detachments and decreased foveal reflexes.

What is your differential diagnosis? What further workup would you pursue?