Older woman presents with progressive diplopia, eye redness and proptosis

A 78-year-old woman was referred to the neuro-ophthalmology service at New England Eye Center for several months of progressive diplopia, bilateral eye redness and proptosis.
The patient’s medical history was significant for hyperlipidemia, diverticulosis, osteopenia and squamous cell carcinoma of the skin. Medications included aspirin, atorvastatin and vitamin D3. Past surgeries included breast biopsy and cataract surgeries in both eyes. She was a former smoker with no reported alcohol or drug use.
Eight months before presentation, she developed binocular vertical diplopia, associated