- 1). Take the patient's history. The onset of optic neuritis usually begins with vision impairment in one eye but may affect both eyes on rare occasions. A change in color perception is a common early symptom of optic neuritis.
- 2). Conduct a physical examination of the eyes. The pupillary response usually is decreased and a Marcus Gunn pupil or relative afferent pupillary defect is commonly seen. The visual acuity also is decreased, although the severity is highly variable.
- 3). Perform specific vision tests. A Pelli-Robson chart measures the patient's sensitivity to contrast and an Ishihara color plate tests the patient's color vision. These results will frequently be below normal in patients with optic neuritis.
- 4). Run laboratory tests to eliminate other possible diagnoses. Blood tests can exclude optic neuropathy and an analysis of the spinal fluid can detect MS. The presence of the neuromyelitis optica-IgG antibody is a specific marker for neuromyelitis optica.
- 5). Take a Magnetic Resonance Imaging (MRI) scan. This is a highly sensitive test for observing the inflammation of the optic nerve and can rule out the possibility of a structural lesion. An MRI also is useful at this point in detecting demyelinative lesions in the brain for patients with MS.