with a measuring caliper or other devices. the patient is then told to look away from the injection site to show the quadrant to be injected, and the doctor inserts the needle at the target site in a single motion into the mid-vitreous cavity. once the needle is in the vitreous cavity, the doctor pushes the plunger to release the drug into the cavity. after that, the needle is removed, and the injection site is immediately covered with a cotton swab to avoid vitreous reflux (reflux of fluid from the vitreous cavity). the excess pvp-i solution is rinsed away. finally, the doctor checks the patient’s vision and intraocular pressure (iop) of the eye. the injection of certain medications, such as triamcinolone acetonide (kenalog or triesence), may cause a sudden increase in the iop, and the patient should be monitored until the pressure returns to a normal level. if a large volume of drug is injected, paracentesis may be required. possible risks and complications side effects of intravitreal injection can be classified into two categories: drug-related side effects and injection-related side effects. for example, in an intravitreal steroid injection, complications could be divided into steroid-related adverse effects and injection-related adverse effects, in which the former most commonly include cataract formation and increase in intraocular pressure (iop). other examples of potential adverse effects are listed as follows: discomfort and pain in the injection sites bleeding (e.g. subconjunctival, vitreous or retinal hemorrhage) vitreous reflux (the reflux of fluid from the vitreous cavity, which contains a mixture of vitreous humor and the drug administered) floaters (black/grey spots, small shapes or string in vision) infectious endophthalmitis pseudoendophthalmitis ocular hypertension, i.e. increase in intraocular pressure (iop) cataract (when the needle accidentally hits the lens), or other damage to lens rhegmatogenous retinal detachment toxic effects of medication a surgery may be required to treat certain severe complications. some of the above complications could also lead to blindness, or even loss of the eye (in the case of a severe infection). precautions precautions should be taken before, during, and after the injection to lower the chances of complications: pre-treatment topical antiseptic is important to prevent potential bacterial infection. common antiseptics used include povidone-iodine (reducing the risk of endophthalmitis) and chlorhexidine (predominantly to counter-act adverse effects caused by povidone-iodine in the aqueous form). pre-injection antibiotics might be given to prevent potential bacterial infection. hand sterilization to eradicate microorganisms on the hands of the physician prior to the injection. sterile gloves should be used. collection of comprehensive information of the patient on health problems, allergies, bleeding tendencies, and medicines taken (including any over-the-counter medicines) to avoid related complications. during the injection masks, drapes, and silence (i.e. both the ophthalmologist should not talk), to minimize aerosolization via respiratory droplets. post-treatment post-injection antibiotics could be given to prevent potential bacterial infection, but is not included in the standard procedures of intravitreal injection. some studies show that it has no statistically significant benefit in preventing endophthalmitis, whereas other studies indicate that it can increase conjunctival bacterial resistance. rubbing of eyes and swimming should be avoided for days after intravitreal injection. eye pain or discomfort, redness, light sensitivity and changes in vision should be reported to intravitreal injection providers.