Optic neuritis refers broadly to inflammatory demyelination, infection, and nonspecific inflammation of the optic nerve. The optic nerve originates in the retina and ends in the geniculate body of the brain, which acts as a transmitter of visual impulses, i.e., the information seen by the eye to the brain. The optic nerve is surrounded by a sheath. Viral infections of the upper respiratory or gastrointestinal tract, mental shock, and vaccination can cause the autoimmune system to attack the myelin sheath of the optic nerve, resulting in myelin loss and inflammatory demyelination. Local or systemic infections, such as intraocular, oral, sinus, middle ear, and intracranial infections, can cause optic neuritis by spreading; pathogens from systemic infections such as diphtheria, scarlet fever, pneumonia, dysentery, typhoid, tuberculosis, septic meningitis, and septicemia can enter the bloodstream and thus cause optic neuritis. Some autoimmune diseases can also cause optic neuritis. Patients with optic neuritis usually experience vision loss, with the most severe visual impairment occurring 1-2 weeks after the onset of the disease, after which vision gradually recovers, with most patients returning to normal vision 1-3 months after the onset of the disease. However, patients with inflammatory demyelination have a dramatic loss of vision after the onset of the disease, and can have severely impaired vision or even no light perception within 1-2 days. In addition to vision loss, patients may also experience flashing sensations and orbital pain, which is especially pronounced when the eye is turned. In summary, optic neuritis is an inflammatory manifestation of the optic nerve that usually causes significant vision loss and requires prompt medical attention.