Understanding Intravitreal Injections
Intravitreal injections are a common procedure used to deliver medication directly into the vitreous—the jelly-like substance that fills the eye [1.6.1, 1.10.4]. This method allows for a high concentration of medication to be placed close to the retina, where it's needed most, maximizing effectiveness and minimizing systemic side effects [1.6.1]. These injections are a primary treatment for several serious retinal conditions that can lead to vision loss, including wet age-related macular degeneration (AMD), diabetic retinopathy, macular edema, and retinal vein occlusion [1.10.2]. The goal is typically to reduce the leakage from and growth of abnormal blood vessels in the retina [1.10.2].
How Long Do Anti-VEGF Injections Last?
The most common class of drugs used for these injections are anti-vascular endothelial growth factor (anti-VEGF) medications [1.10.2]. VEGF is a protein that stimulates the growth of abnormal, leaky blood vessels in the eye [1.2.2]. By blocking this protein, these drugs help stabilize and sometimes even improve vision.
The duration of effect for anti-VEGF injections varies by the specific drug:
- Avastin (bevacizumab) and Lucentis (ranibizumab): These were among the first widely used anti-VEGF drugs. Treatment with these medications often requires injections every four to six weeks, especially during the initial phase [1.2.4, 1.5.5].
- Eylea (aflibercept): Eylea was developed to last longer than early options. After an initial loading phase of monthly injections, many patients can extend their treatment interval to once every eight weeks [1.3.1].
- Beovu (brolucizumab): This medication was designed for extended duration, with some patients able to go up to 12 weeks between injections after the initial doses [1.3.1].
- Vabysmo (faricimab-svoa): As one of the newest options, Vabysmo targets two different pathways (VEGF and Ang-2) that cause vessel leakage [1.3.5]. This dual-action mechanism allows many patients to extend their treatment intervals to every 8, 12, or even 16 weeks [1.2.1, 1.3.5].
- Eylea HD: This is a higher-dose formulation of Eylea designed to extend the time between treatments, potentially allowing for injections only three or four times a year [1.2.1, 1.3.5].
How Long Do Corticosteroid Injections Last?
For some eye conditions, particularly those involving significant inflammation like diabetic macular edema or uveitis, corticosteroids are used [1.4.3, 1.10.2]. Unlike anti-VEGF shots, which are liquid medications, some steroids are delivered as tiny, biodegradable implants that release the drug slowly over time.
- Ozurdex (dexamethasone intravitreal implant): This implant releases medication and is effective for an extended period, typically lasting up to six months, though some real-world studies show an average retreatment time closer to five months [1.4.1, 1.4.5]. Its peak effectiveness is often seen between 60 and 90 days post-injection [1.4.2].
- Iluvien (fluocinolone acetonide intravitreal implant): This is another long-lasting option, primarily for diabetic macular edema, that can release a continuous low dose of a corticosteroid for up to 36 months (3 years).
Comparison of Common Eye Injection Medications
| Medication | Type | Typical Treatment Frequency | Common Conditions Treated |
|---|---|---|---|
| Avastin, Lucentis | Anti-VEGF | Every 4-6 weeks [1.2.4, 1.5.5] | Wet AMD, Diabetic Retinopathy, Macular Edema [1.10.2, 1.10.3] |
| Eylea | Anti-VEGF | Every 8 weeks (after loading doses) [1.3.1] | Wet AMD, Diabetic Macular Edema [1.3.2] |
| Vabysmo | Anti-VEGF / Anti-Ang-2 | Every 8-16 weeks (after loading doses) [1.2.1] | Wet AMD, Diabetic Macular Edema [1.3.5] |
| Ozurdex | Corticosteroid Implant | Every 4-6 months [1.4.1, 1.4.5] | Macular Edema, Uveitis, Retinal Vein Occlusion [1.4.3] |
The Injection Procedure: What to Expect
The thought of an eye injection can be daunting, but the procedure is quick and measures are taken to ensure comfort [1.7.4]. The entire appointment may take around 20 minutes [1.7.1].
- Preparation: Your eye will be numbed with anesthetic drops or gel to minimize discomfort. The eye and surrounding area are cleaned with an antiseptic, often iodine, to prevent infection [1.6.1, 1.7.2].
- Stabilization: A small device called a speculum is used to gently hold your eyelids open, so you don't have to worry about blinking [1.6.1].
- The Injection: You will be asked to look in a specific direction. The ophthalmologist then uses a very thin needle to inject the medication through the sclera (the white part of the eye) [1.7.2]. Most patients report feeling only a brief moment of pressure [1.7.4].
- Aftercare: After the injection, you may experience some minor irritation, a red spot on the eye, or see floaters (which can be tiny air bubbles from the syringe) for a few days [1.6.2, 1.6.4]. It is crucial not to rub the eye and to follow all post-procedure instructions, such as avoiding swimming for a few days [1.6.2, 1.6.5].
The Future: Longer-Lasting Treatments
Significant research is focused on extending the duration between treatments to reduce the burden on patients. Innovations on the horizon include:
- Gene Therapy: The goal is a potential 'one-and-done' treatment where the eye is enabled to produce its own anti-VEGF medicine [1.8.1].
- Refillable Implants: The Port Delivery System (PDS) is a tiny, surgically implanted reservoir that can be refilled with medication in-office, potentially only once or twice a year. Though voluntarily recalled in 2022, it may become available again [1.8.1, 1.8.2].
- New Drug Formulations: New therapies are continuously being developed to be more durable, with some in clinical trials showing potential for efficacy lasting six months or more between injections [1.8.1].
Conclusion
The answer to how long do eye injections last? is not a single number but a range—from about four weeks to several years. The evolution of pharmacology has moved treatments from frequent monthly visits to intervals stretching for many months, significantly improving the quality of life for patients with chronic retinal conditions. The duration depends heavily on the specific medication, whether it's an anti-VEGF agent or a steroid implant, and how an individual’s eye responds to treatment. Ongoing advancements in drug delivery and gene therapy promise an future with even less frequent interventions.
For more information on the effectiveness of different anti-VEGF regimens, you can review this analysis from the National Institutes of Health: https://pmc.ncbi.nlm.nih.gov/articles/PMC7202375/
