Intravitreal injections (IVT) have become a standard, highly effective medical procedure for managing various serious diseases that affect the back of the eye. IVT delivers medication directly into the vitreous humor, the clear, jelly-like substance filling the large cavity at the center of the eyeball. This targeted approach allows for a significantly higher, more concentrated dose of medicine to reach the retina and macula compared to taking medication by mouth or through a vein. The procedure is performed by a retina specialist and is now a common tool for preserving sight for millions of people worldwide.
Conditions Treated by IVT
Intravitreal injections are necessary for numerous conditions where abnormal blood vessel growth or swelling threatens the light-sensitive tissues of the retina. The most frequently treated condition is wet Age-related Macular Degeneration (AMD), where fragile, new blood vessels grow underneath the macula and leak fluid or blood, rapidly causing central vision loss. IVT treatment helps to stop this abnormal vessel growth and reduce the associated leakage, stabilizing or even improving vision.
Diabetic Retinopathy and its complication, Diabetic Macular Edema (DME), are also major indications for this treatment. In DME, high blood sugar levels damage the retinal blood vessels, causing them to leak fluid into the macula, resulting in swelling and blurred vision. The injections work to reduce this swelling and prevent further damage to the retina.
Another group of diseases treated with IVT includes Retinal Vein Occlusions (RVO), such as Branch or Central RVO, which occur when a blood clot blocks a vein in the retina. This blockage causes blood and other fluids to leak into the retinal tissue, leading to significant macular swelling. The medication delivered by IVT helps to resolve this fluid accumulation and reduce the inflammation caused by the blocked circulation. Other conditions like severe eye infections (endophthalmitis) and chronic inflammation inside the eye (uveitis) also rely on IVT to deliver antibiotics or anti-inflammatory drugs directly to the infected or inflamed site.
How the Injection Procedure Works
The intravitreal injection procedure is typically performed in a clean, dedicated treatment room within the doctor’s office and usually takes about 10 to 15 minutes from preparation to completion. The first step involves anesthetizing the eye’s surface using topical anesthetic drops or a gel, ensuring the patient feels little to no pain during the injection itself, though a feeling of pressure is common.
Next, the eye and surrounding eyelids are thoroughly cleaned with an antiseptic solution, most commonly povidone-iodine, which prevents infection inside the eye. A small, sterile device called an eyelid speculum is then gently placed to hold the eyelids open and prevent the patient from blinking during the brief injection.
The retina specialist then uses a tiny, fine-gauge needle to inject a very small volume of medication, typically around 0.05 milliliters, through the pars plana, which is the white part of the eye. The injection site is carefully measured, usually 3.5 to 4 millimeters away from the limbus, the border between the cornea and the sclera, to avoid damaging the lens or retina. The injection itself is very quick, taking only a few seconds, and the speculum is immediately removed afterward.
Types of Medication Delivered
The primary category of drugs administered via IVT is the Anti-Vascular Endothelial Growth Factor (Anti-VEGF) agents. These medications have transformed the treatment of wet AMD, DME, and RVO by targeting the protein known as Vascular Endothelial Growth Factor (VEGF). VEGF is a signaling protein that stimulates the growth of new, often weak and leaky, blood vessels in the retina. Anti-VEGF agents work by binding to this protein, effectively inhibiting its ability to trigger abnormal blood vessel formation and leakage.
The other major class of medication delivered through IVT is corticosteroids, which are powerful anti-inflammatory agents. Corticosteroids are used to manage persistent macular swelling and inflammation associated with conditions like RVO, DME, and uveitis. These drugs suppress the body’s inflammatory response and help reduce damage to the blood-retinal barrier.
Certain antibiotics, antivirals, and antifungals are also administered via IVT to treat severe intraocular infections, such as endophthalmitis, where rapid and targeted drug delivery is necessary to save the eye and vision.
What to Expect After Treatment
Following the procedure, patients may experience several temporary and common side effects that resolve quickly. It is normal to feel some mild discomfort, a gritty or scratchy sensation, or irritation in the eye for the first 24 to 48 hours as the numbing drops wear off. A small spot of blood, known as a subconjunctival hemorrhage, may appear on the white of the eye at the injection site, but this is harmless and typically fades completely within a week.
Many patients report seeing new floaters immediately following the injection, which can appear as specks, bubbles, or a cloudy spot. These are usually tiny air bubbles or dispersed medication and nearly always dissipate within a few hours to a few days as the eye naturally absorbs them. Patients are advised to take over-the-counter pain relievers for mild discomfort and use artificial tears to alleviate any dry or gritty feeling.
Post-treatment care involves avoiding rubbing the eye and refraining from swimming or wearing contact lenses for a couple of days to prevent contamination. Adherence to the treatment schedule is important, as most conditions treated by IVT, such as AMD and DME, are chronic and require repeated, scheduled injections to maintain the therapeutic effect. It is important to contact the retina specialist immediately if severe, worsening pain, a significant decrease in vision, or a dark shadow or curtain appears in the field of vision, as these can be rare warning signs of a serious complication like infection.