An intravitreal injection is a shot of medication delivered directly into the jelly-like fluid (the vitreous) that fills the inside of your eye. It’s the primary way doctors treat diseases affecting the back of the eye, including wet age-related macular degeneration, diabetic retinopathy, and conditions that cause swelling in the retina. The procedure takes only a few minutes in a doctor’s office, and while the idea of a needle in the eye sounds alarming, most patients report feeling only slight pressure during the injection.
Why Medication Goes Directly Into the Eye
The back of the eye is difficult to reach with pills or standard eye drops. Oral medications get diluted throughout the body before reaching the retina, and topical drops can’t penetrate deep enough. Injecting directly into the vitreous bypasses those barriers, delivering a high concentration of the drug exactly where it’s needed. This targeted approach also means far less medication enters the rest of your body, reducing the chance of side effects elsewhere.
Conditions Treated With Eye Injections
The most common reason people receive intravitreal injections is wet age-related macular degeneration (wet AMD), a condition where abnormal blood vessels leak fluid beneath the retina and threaten central vision. The injections work by blocking a protein called VEGF that drives the growth of those abnormal vessels.
Other conditions treated this way include:
- Diabetic retinopathy and diabetic macular edema: damage and swelling in the retina caused by diabetes
- Retinal vein occlusion: a blockage in the veins that drain blood from the retina, leading to fluid buildup
- Uveitis: inflammation inside the eye that can blur vision and damage tissue
- Ocular histoplasmosis syndrome: a rare fungal infection that scars the retina
For conditions driven by abnormal blood vessel growth, doctors use anti-VEGF drugs. For swelling and inflammation, they may use steroid medications instead, either as a liquid injection or a tiny slow-release implant placed inside the eye.
What Happens During the Procedure
The entire process, from preparation to the injection itself, typically takes about 10 to 15 minutes. Most of that time is spent on cleaning and numbing. Here’s what to expect.
First, the doctor places numbing drops in your eye. Then they clean the skin around the eye and the eye’s surface with an antiseptic solution and let it sit for about a minute to disinfect. A sterile drape is placed over your face so only the treated eye is exposed, and a small device called a speculum holds the eyelids open so you don’t need to worry about blinking.
The doctor may press an anesthetic-soaked pad against the injection site for a minute or so for extra numbing. Using a measuring tool, they mark a precise spot a few millimeters behind the front edge of the eye, in a region called the pars plana. This location provides a safe entry point into the vitreous cavity without risking damage to the lens or retina.
After a brief warning, the needle goes in quickly, the medication is injected, and the needle is removed. The needle is very fine (roughly the width of a thick sewing needle), and the puncture site seals on its own without stitches.
How It Feels and What to Expect After
During the injection, most people feel slight pressure but not pain. Some notice a web of lines in their vision as the medication mixes with the vitreous fluid. Afterward, mild irritation or a burning sensation is common but typically fades within a day. Your eye may be sore and your vision slightly foggy for a day or two before clearing up.
Floaters are normal in the first few days and usually disappear on their own. You might also see a small red spot on the white of the eye, similar to a bruise, which resolves within one to two weeks. Over-the-counter pain relievers like acetaminophen or ibuprofen handle any lingering discomfort, and a cool, clean washcloth held gently against the closed eye can also help.
For the first week after the injection, watch for signs of infection: increasing pain, significant vision loss, or worsening redness. These are rare but warrant a prompt call to your eye doctor.
How Often You’ll Need Injections
Intravitreal injections are rarely a one-time treatment. Most conditions require repeated injections over months or years. The schedule depends on the disease, how your eye responds, and which dosing strategy your doctor uses.
Treatment usually begins with a “loading phase” of monthly injections for the first three months or so. After that, many doctors use a “treat and extend” approach: if your eye is stable, they gradually push the interval between injections longer (say, from four weeks to six, then eight). If the disease flares, the interval gets shortened again. This approach reduces the total number of injections compared to sticking with a strict monthly schedule. In studies, treat-and-extend patients received roughly four to five fewer injections per year than those treated monthly, with similar vision outcomes. It also means fewer office visits, since each appointment doubles as both a check-up and a treatment.
Some doctors instead use an “as needed” approach, where you come in regularly for monitoring but only get an injection if the disease shows signs of activity. This involves the fewest injections but requires more frequent check-up visits.
How Well the Injections Work
For wet AMD and diabetic eye disease, anti-VEGF injections have been transformative. In clinical trials, patients consistently gain vision or at least hold steady rather than losing it. Real-world results tend to be a bit more modest, partly because patients outside trials don’t always keep up with the injection schedule. In large observational studies, patients who received more injections consistently achieved better vision than those who received fewer, reinforcing how important it is to stick with the treatment plan your doctor recommends.
The goal for most patients isn’t necessarily dramatic improvement. Stabilizing vision and preventing further loss is a significant win, especially for progressive diseases like wet AMD that would otherwise lead to worsening blindness.
Risks and Safety
Intravitreal injections have a strong safety record. The most serious potential complication is endophthalmitis, a severe infection inside the eye. In a study of over 650,000 injections, this occurred at a rate of about 1 in 2,857 injections (0.035%). The risk per individual injection stays very low even for patients who receive dozens of treatments over the years. Cumulative risk does increase with the total number of injections, but at a rate that slows significantly over time: after 35 injections, the cumulative risk per eye was about 0.38%, rising only slightly to around 0.50% after 126 injections.
Other uncommon risks include retinal detachment, elevated eye pressure, and bleeding inside the eye. The careful cleaning and antiseptic steps performed before every injection exist specifically to minimize infection risk, which is why it’s important that the procedure is done in a properly equipped clinical setting.
Who Should Not Receive Them
Intravitreal injections are not given when there’s an active infection in or around the eye. Active inflammation inside the eye can also be a contraindication for certain medications, particularly if the inflammation involves the retinal blood vessels or surrounding tissue. Your eye doctor will evaluate the surface and interior of your eye before each injection to make sure it’s safe to proceed.