Optic neuritis

An inflammatory neuropathy of the optic nerve (cranial nerve II), typically causing unilateral painful visual loss, dyschromatopsia, and visual field defects. Possible causes are demyelinating autoimmune disease (multiple sclerosis, neuromyelitis optica, MOGAD, lupus, sarcoidosis), viral infections (measles, mumps, rubella, chickenpox, herpes, viral encephalitis), and bacterial infections (sinusitis, syphilis, tuberculosis, meningitis, Lyme disease).