Infiltrative optic neuropathy (ION) is characterized by the infiltration of tumor cells or inflammatory cells in the optic nerve and its sheath. ION is rare in clinic practice, and ION caused by direct infiltration or metastasis of malignant tumors is easily misdiagnosed as optic perineuritis or optic neuritis, which means delayed proper treatment and makes patients risking possible side effects of steroid therapy. Currently, ophthalmologists are lack of sufficient knowledge about ION, which contributes to the high rate of misdiagnosis and missed diagnosis of ION in clinical practice. The diagnosis and treatment of ION have not yet formed systematic standardized guidelines. Therefore, Neuro-ophthalmology Group of Ophthalmology Branch of Chinese Medical Association organized experts to propose consenus of opinions on definition, diagnosis and treatment of ION, which helps to guide clinical diagnosis and treatment of ION, as well as basic researches about ION.