Ethambutol is a bacterium inhibitor for tuberculosis and is effective against Mycobacterium tuberculosis. It is commonly used in patients with pulmonary tuberculosis, bone tuberculosis and tuberculous pleurisy. However, ethambutol may cause adverse eye reactions and even double vision, which is often overlooked by doctors and patients. Generally speaking, the side effects of ethambutol are dose-related, and the incidence of ocular adverse reactions is 1%-2% when the daily dosage is ≥25mg/kg, and less (0.8%) when it is ≤15mg/kg. The main manifestations are decreased visual acuity; reduced visual field; reduced color vision, especially green color vision; the fundus of the eye may have postbulbar optic neuritis or optic nerve papillitis or optic nerve atrophy manifestations. Most of the above ocular side effects occur suddenly and occasionally are latent. Symptoms of optic neuritis usually begin to occur 3 – 6 months after the drug is administered. There is a risk of bilateral blindness due to the use of ethambutol. Therefore, caution should be exercised before and after the use of ethambutol. 1.Ophthalmologic examination should be done before treatment. If there is a history of optic nerve atrophy or optic neuritis, written consent of the patient should be obtained. 2.The chance of optic neurotoxicity will be increased in patients with renal disease and diabetes mellitus. 3. When treating with ethambutol, patients should be instructed to test their visual acuity and color vision at home, especially for red and green color vision. If the daily dose is greater than 15mg/kg, an eye examination should be performed every 2 to 4 weeks. Including visual acuity, visual field and color vision examination. 4. If ocular adverse reactions are found, ethambutol should be discontinued immediately and relevant ophthalmic examinations should be performed. Generally speaking, if found in time, the vision will be restored after discontinuing the drug, usually within 3 to 12 months after discontinuing the drug, the vision will be restored to varying degrees, but a few of the more serious cases cannot be restored. 5, optic nerve poisoning patients 3 times a day oral zinc sulfate 100 ~ 250mg; daily without the gastrointestinal tract to give vitamin B12 and other treatment for 10 ~ 28 weeks, also has a certain effect.