Vitreous cavity injection is an important treatment method for ophthalmic diseases. Compared with other routes of drug delivery, it is not limited by the blood-ocular barrier and can achieve higher drug concentrations in a short period of time, thus enhancing the therapeutic effect, reducing systemic toxicity and better controlling the progression of the disease. However, vitreous cavity injection is also associated with complications such as elevated intraocular pressure, subconjunctival hemorrhage, corneal epithelial damage, vitreous hemorrhage, and endophthalmitis. The main applications include: (a) anti neovascularization drugs vitreous cavity injection: aimed at inhibiting neovascular growth, reducing exudation, edema, and thus stabilizing or improving visual acuity (mainly Compazepine and Ranibizumab). (1) macular edema caused by various causes (including diabetic macular edema, macular edema caused by various diseases such as post-cataract surgery or post-uveitis;) (2) choroidal neovascular membrane formation caused by various causes (including age-related macular degeneration, highly myopic macular degeneration, mid-bleed, etc.); (3) retinal neovascularization (such as diabetic retinopathy, venous obstruction, retinal perivasculitis, (3) retinal neovascularization (such as diabetic retinopathy, venous obstruction, retinal periphlebitis, Coat’s disease, choroidal osteoma, choroidal hemangioma, etc.); (4) neovascular glaucoma and other diseases. (B) antibacterial drug vitreous cavity injection: the existence of intravitreal blood vessels and blood-eye barrier severely limits the concentration of drugs in the vitreous cavity, resulting in the vitreous once infected, the anti-inflammatory effect is not significant, intraocular infection for a long time will seriously damage the function of the retina. Therefore, early vitreous cavity drug delivery is the preferred method to increase the concentration of intravitreal antibacterial drugs for a short period of time. Preoperative preparation: (1) Patients need to fully understand the risks of injection, understand that a single treatment cannot completely solve the problem, and sign the surgical consent form only after fully informed and accepted. (2) Frequent antibiotic eye drops are required 3 days before the proposed injection to prevent infection, while routine blood tests such as routine blood count and coagulation, monitoring of the patient’s general condition such as blood sugar and blood pressure, to avoid cardiovascular and cerebrovascular accidents; (3) Tear duct flushing should be performed one day before the injection, and drug injection should be suspended if there is purulent secretion, and drug injection should also be suspended if the bulbar conjunctiva is found to be significantly congested and edematous before surgery, with symptoms of conjunctivitis, etc., to avoid infection. (4) It is best to be accompanied by someone on the day of injection, and generally both eyes are not injected at the same time. Postoperative requirements: at least 1 hour of postoperative observation before leaving the hospital, if there is no special circumstances, generally do not remove the gauze; the first day, the third day, the seventh day of postoperative need to review the follow-up outpatient; at least 3 consecutive days of antibiotic eye drops, at least 4 times a day; if there is obvious eye pain, obvious blurred vision, eye redness and congestion, etc., should immediately contact the doctor, or in the local hospital ophthalmology consultation, mainly to understand whether there is infection The main purpose is to find out whether there is any infection. Note: Pre- and post-operative antibiotics and eye dilating solution should be fresh and sterile! Common post-operative conditions: (1) floating flocculent or circle-like objects in front of the eyes after surgery: this may be the drug floating in the vitreous or a small amount of gas residue, there is no need to be nervous; (2) after surgery found under the conjunctiva flaky bleeding: this may be the injection of small blood vessels bleeding, it is not terrible, usually about 10 days to absorb on their own. (3) Eye pain and discomfort on the day of surgery, more tears and foreign body sensation may be corneal epithelial damage, if the pain is really unbearable, you need to go to the hospital in time.