According to research findings, the retina is particularly metabolically active, with blood flow about 20 times more than brain tissue, and has a high degree of binding power with certain drugs, especially in the case of long-term mass drug use, is extremely vulnerable to damage. The following drugs, if applied carelessly, may cause blindness: 1, isotretinoin Isotretinoin is commonly used in severe acne, especially for nodular cystic acne. Because of the action on the conjunctiva, cornea, can cause conjunctivitis, severe corneal clouding, visual impairment, optic papilledema. It can cause congenital blindness in the fetus when taken by pregnant women. Isotretinoin can cause birth defects and should not be taken during pregnancy. Pregnancy while taking any dose of isotretinoin, even for a short period of time, is associated with a very high risk of serious birth defects. Women of childbearing age or their spouses should use effective contraception for 3 months before starting treatment with isotretinoin, during treatment and for 3 months after stopping the drug. 2, hydroxychloroquine and chloroquine antimalarial drugs hydroxychloroquine and chloroquine, especially hydroxychloroquine is now mostly used in the treatment of rheumatoid arthritis, juvenile chronic arthritis, discoid and systemic lupus erythematosus and other diseases. Hydroxychloroquine and chloroquine can cause photophobia, impaired color vision, loss of visual acuity and then loss of central reflex (visual redness blindness) and blindness due to their action on the retina. Before starting treatment, all patients should undergo an ophthalmologic examination, which includes visual acuity sensitivity, ophthalmoscopy, central visual field and color vision. Thereafter, examinations should be performed at least once a year. 3, chloramphenicol eye drops Chloramphenicol eye drops in high doses for long term use (≥ 3 months) can cause optic neuritis or optic nerve papillitis (especially in pediatric patients). Patients with long-term application of eye drops should have prior eye examination and close attention to the patient’s visual function and symptoms of optic neuritis, and discontinue the drug once it appears. Also take vitamin C and vitamin B.