Infectious and infection-related optic neuritis is an important type of optic neuritis. Infectious optic neuritis is caused by direct spread of pathogenic organism to optic nerve from local infection or blood transmission. Infection-related optic neuritis is caused by pathogens-induced immune allergic reaction. They present with atypical clinical features of optic neuritis, including progressive vision loss, persistent eye pain or headache, ineffectiveness or even worse of glucocorticoid therapy. Fundus manifestations include optic disc swelling with peripapillary hemorrhage or neuro-retinitis, and the feature of concurrent uveitis. When these patients first visit ophthalmic clinics, they often lack signs of systemic infection, thus it is easy to misdiagnose them as other types of optic neuropathy and mistakenly treat them. In particular, high-dose glucocorticoid therapy can lead to very serious consequences. Therefore, how to correctly diagnose infectious and infection-related optic neuritis in the early stages are very important for ophthalmologists and need to be seriously kept in our mind.