"Optic neuritis" that is neither

A 28-year-old African American woman developed periocular pain worsening with eye movement and decreased vision in her left eye. A diagnosis of left optic neuropathy was made based on the findings of decreased vision in the left eye, a left relative afferent pupillary defect, and mild optic disc hyperemia in the left eye (figure 1), with normal retinae and maculae bilaterally. Automated perimetry showed a small central scotoma in the left eye. The pain with eye movements suggested an inflammatory mechanism (i.e., optic neuritis). Her neurologic examination was normal. MRI of the brain showed 2 small T2 hyperintense lesions in the right inferior frontal lobe and left periatrial white matter. The lesions did not enhance. Angiotensin converting enzyme level was slightly elevated. A chest CT was negative for pulmonary sarcoidosis. She did not receive steroids, and her visual function improved spontaneously over a few weeks. She had no neurologic symptoms and the diagnosis of clinically isolated syndrome was made. The patient declined treatment with an immunomodulatory agent.