**5. Ophthalmologic evaluation**

A thorough history is necessary regarding the onset, duration, and characteristics of symptoms. All patients should be questioned about recent fever and respiratory symptoms. Ophthalmologic evaluation must be complete to rule out other differential diagnoses. Measurement of visual acuity, intraocular pressure, pupil and dilated fundus examination, color testing to evaluate patients for evidence of optic neuropathy, extraocular motility (searching for nystagmus or cranial neuropathies), visual field testing (to investigate deficits related to stroke or optic neuropathy).

In the presence of optic neuritis or neurologic symptoms, neuroimaging must be done. Additional serum or cerebrospinal fluid testing may be useful [6].
