Question: Can you identify this condition?

A 42-year-old female smoker presents to your office complaining of binocular vertical diplopia. Clinical examination reveals normal vision, pupil reactivity, and visual fields. There is no relative afferent pupillary defect; however, there is evidence of proptosis of the right eye, with restricted elevation of that eye during upward gaze. Magnetic resonance imaging is shown above.

The most likely diagnosis is

1. Myasthenia gravis

2. Horner syndrome

3. Thyroid orbitopathy

4. Preseptal cellulitis

Answer on page 492

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