A 69-year-old male presents to the emergency department for evaluation of diplopia. Three days prior, he had developed left-sided periorbital and ocular aching pain. He then noticed decreased peripheral vision on the left. The patient denies worsening pain with extraocular muscle movement. He also denies photosensitivity, eye redness, discharge, flashing lights, floaters, or a curtain or veil over his vision. He hasn’t experienced headache, temple pain, jaw claudication, or fever, and there are no other neurological symptoms, such as extremity numbness, weakness, or slurred speech. He denies any recent trauma.
On physical examination, he is afebrile, and his vital signs are within normal limits. His ocular exam is notable for the following:
- Left eye: ptosis, weak adduction, no abduction
- Pupils: 3 mm bilaterally and reactive to light
- Visual acuity: right eye 20/30, left eye 20/25, no afferent pupillary defect
The remainder of his examination is normal.