Intravitreal administration

Intravitreal administration is a route of administration of a drug, or other substance, in which the substance is delivered into the vitreous humor of the eye. "Intravitreal" literally means "inside an eye". Intravitreal injection is the method of administration of drugs into the eye by injection with a fine needle. The medication will be directly applied into the vitreous humor.^[1] It is used to treat various eye diseases, such as age-related macular degeneration (AMD), diabetic retinopathy, and infections inside the eye such as endophthalmitis.^[1] As compared to topical administration, this method is beneficial for a more localized delivery of medications to the targeted site, as the needle can directly pass through the anatomical eye barrier (e.g. cornea, conjunctiva and lens) and dynamic barrier (e.g. tears and aqueous humor).^[2][3] It could also minimize adverse drug effects on other body tissues via the systemic circulation, which could be a possible risk for intravenous injection of medications.^[2][4] Although there are risks of infections or other complications, with suitable precautions throughout the injection process, chances for these complications could be lowered.^[5]

Intravitreal injections were first introduced in 1911 when Ohm gave an injection of air into the vitreous humor to repair a detached retina. In the mid-1940s, intravitreal injections became a standard way to administer drugs to treat endophthalmitis and cytomegalovirus retinitis.^[6]