IVI stands for intravitreal injection, a procedure where medication is delivered directly into the jelly-like fluid (called the vitreous) inside your eye. It’s one of the most common treatments in ophthalmology, primarily used to manage conditions that threaten vision by targeting the retina at the back of the eye. Millions of these injections are performed worldwide each year. In a separate context, IVI can also refer to intravaginal insemination, a simple fertility technique, which is covered later in this article.
How Intravitreal Injections Work
The retina sits at the back of the eye, and getting medication to it through pills or standard eye drops is difficult. The drugs would be diluted throughout the body or blocked by the eye’s natural barriers long before reaching the target. By injecting medication directly into the vitreous, the jelly-like substance that fills the eye, doctors deliver a concentrated dose right where it’s needed.
The most widely used medications for IVI are anti-VEGF drugs. VEGF is a protein your body produces that triggers the growth of new blood vessels. In certain eye conditions, this process goes haywire, and abnormal blood vessels leak fluid or blood into the retina, damaging your central vision. Anti-VEGF drugs block that protein and slow or stop the damage. The National Eye Institute lists five commonly used options: bevacizumab (Avastin), ranibizumab (Lucentis), aflibercept (Eylea), brolucizumab (Beovu), and faricimab (Vabysmo).
Conditions Treated With IVI
The most common reason for intravitreal injections is wet age-related macular degeneration (wet AMD), a condition where abnormal blood vessels grow beneath the retina and leak, causing rapid vision loss if untreated. IVI is also used for diabetic retinopathy, where high blood sugar damages retinal blood vessels, and for retinal vein occlusion, where a blocked vein causes swelling and bleeding in the retina.
In all of these conditions, the underlying problem involves blood vessels behaving abnormally. Anti-VEGF injections target that shared mechanism, which is why one class of drugs can treat several different diagnoses.
What the Procedure Feels Like
The idea of a needle in your eye sounds alarming, but the procedure is quick and designed to minimize discomfort. The entire process typically takes only a few minutes. Before the injection, your eye is numbed using one of several methods: anesthetic drops (the most common approach), a lidocaine gel applied to the eye’s surface, or a small injection of lidocaine beneath the clear membrane covering the white of the eye. The eye and surrounding area are then cleaned with an antiseptic solution to prevent infection.
A very thin needle is inserted through the white part of the eye, about 3.5 to 4 millimeters behind the colored part, angled toward the center of the eye. You may feel pressure or a brief sting, but most patients report that the anticipation is worse than the actual sensation. During the procedure, providers wear surgical masks or minimize talking to reduce the risk of airborne bacteria reaching the eye. Afterward, the injection site is rinsed and you may be given an eye pad to wear for about two hours.
How Often You’ll Need Treatment
IVI is rarely a one-time event. Treatment typically begins with a loading phase of monthly injections for the first three months. After that, the schedule depends on how your eye responds. Two common approaches exist: fixed dosing, where you receive an injection at set intervals (often every eight weeks), and treat-and-extend, where your doctor gradually lengthens the time between injections as long as your eye stays stable.
The treat-and-extend approach has become increasingly popular because it can achieve the same visual results as fixed dosing while reducing the number of clinic visits. In one clinical trial, 37% of patients on a treat-and-extend schedule were able to stretch their treatment intervals to 12 weeks or longer. Your ophthalmologist will monitor your retina at each visit and adjust the timing accordingly.
How Well IVI Works
For wet AMD, the results are strong. A real-world study tracking over 1,000 eyes found that vision was stable or improved in 90% of cases after an average of three years of treatment. About 63% of patients gained a meaningful improvement in vision, and 35% achieved a substantial gain. Another 27% maintained their existing level of vision without further decline. These numbers reflect what happens in everyday clinical practice, not just controlled trials, making them a realistic picture of what to expect.
The key factor in outcomes is consistency. Patients who stick to their treatment schedule and follow-up appointments tend to do better than those who miss injections or delay care.
Risks and Side Effects
The most serious risk is endophthalmitis, an infection inside the eye. This is rare. Published rates range from about 0.02% to 0.08% per injection, and some centers report even lower numbers. One large study of over 22,000 injections recorded a single case, putting the rate at 0.004%. The antiseptic preparation before each injection is the primary safeguard against this.
More common but less serious side effects include temporary redness at the injection site, mild soreness, and small floaters or spots in your vision for a day or two. A temporary spike in eye pressure can occur but usually resolves on its own within minutes to hours.
What to Watch for After Treatment
Recovery is straightforward. Most people return to normal activities the same day. If you’re given an eye pad, you can remove it after two hours. Over-the-counter pain relief like paracetamol (acetaminophen) is enough if you have any lingering discomfort. You may be prescribed antibiotic or anti-inflammatory eye drops to use for a few days.
Three symptoms require prompt medical attention: severe pain that doesn’t respond to simple pain relief, a noticeable worsening or loss of vision, and new or increasing floaters or cloudiness in the days following the injection. These could signal a complication like infection or retinal detachment, and early treatment makes a significant difference in outcomes.
IVI in Fertility Treatment
In reproductive medicine, IVI refers to intravaginal insemination, a completely different procedure. This involves placing a semen sample directly into the vagina using a needleless syringe, mimicking natural conception. It’s the simplest form of assisted reproduction and can be done at home without medical supervision.
IVI is most commonly used by couples who have difficulty with intercourse due to sexual dysfunction, such as vaginismus or erectile difficulties. It requires no ovarian stimulation, no anesthesia, and no repeated clinic visits. Compared to intrauterine insemination (IUI), which involves threading a catheter through the cervix and costs considerably more, IVI is noninvasive and inexpensive. It’s often recommended as a first step before moving to more intensive fertility treatments like IUI or IVF, particularly when the underlying issue is related to the physical act of intercourse rather than sperm quality or ovulation problems.