An Intravitreal Injection (IVT) is a common, targeted medical procedure fundamental in treating serious conditions affecting the back of the eye. This treatment is necessary to preserve or improve vision by delivering medication directly where it is needed most. While the thought of an injection into the eye may seem daunting, the procedure is highly routine and quick. The precision of the IVT method allows specialists to bypass the eye’s natural protective barriers, ensuring therapeutic drug concentrations reach the retina and macula.
Defining Intravitreal Injections
An intravitreal injection administers medication directly into the vitreous cavity, the largest space in the eye. The term “intravitreal” means “inside the vitreous,” referring to the clear, gel-like substance (vitreous humor) that fills the eye’s center. Delivering the drug here ensures it reaches the target tissues, specifically the retina and macula, with minimal dilution.
The eye’s natural defenses, such as the blood-retinal barrier, prevent most orally or intravenously administered medications from reaching the retina effectively. The IVT technique solves this by depositing a precise dose of medicine directly into the posterior chamber. This targeted delivery allows for much higher local drug levels necessary for treating delicate retinal structures.
Eye Conditions Requiring IVT
Intravitreal injections are the standard treatment for several chronic eye conditions that threaten central vision. One frequently treated disease is Wet Age-Related Macular Degeneration (AMD), where abnormal, fragile blood vessels grow beneath the macula, leaking fluid and blood. The localized treatment stops this neovascularization and reduces swelling.
Diabetic Macular Edema (DME) occurs when high blood sugar levels damage retinal blood vessels, causing them to leak fluid into the macula. This leakage leads to swelling, which blurs central vision and requires localized therapy to reduce the fluid accumulation. Retinal Vein Occlusion (RVO) involves a blockage in a retinal vein, causing blood and fluid to flood the retina and resulting in significant macular edema. All these conditions involve excess fluid or abnormal blood vessel growth managed by direct medication delivery.
The IVT Procedure Experience
The entire IVT process is performed in an office setting and is generally completed in 10 to 15 minutes, with the injection itself taking only a few seconds. Patient comfort is managed through topical anesthetic drops or gel applied to the eye’s surface, thoroughly numbing the area. This numbing agent ensures the patient feels little to no pain, though a sensation of pressure during the injection is common.
Before the injection, the eye and eyelids are cleaned with an antiseptic solution, typically povidone-iodine, to prevent infection. An eyelid speculum is placed to hold the eyelids open and prevent blinking. The medication is injected through the pars plana (the white part of the eye) using a fine needle. Following the injection, the speculum is removed, and the eye is cleaned again; some patients note temporary grittiness or small floaters, which usually resolve quickly.
Medications Delivered Through IVT
The primary class of drugs delivered via IVT are anti-VEGF agents (anti-Vascular Endothelial Growth Factor). VEGF is a protein that promotes the growth of new blood vessels and increases the permeability of existing ones. By inhibiting VEGF, these agents stop the formation of abnormal, leaky blood vessels associated with Wet AMD, DME, and RVO, reducing fluid leakage and swelling in the retina.
Corticosteroids represent the second category of medication used in IVT, often employed when inflammation is a component of the disease or when a patient does not respond to anti-VEGF therapy. Corticosteroids suppress the inflammatory response and inhibit the production of inflammatory molecules. They treat conditions like macular edema secondary to RVO or persistent DME, sometimes delivered as a long-acting implant that slowly releases the drug over several months.