Understanding Eylea (aflibercept) and Avastin (bevacizumab) Eye Injections
Understanding Anti-VEGF Treatment
VEGF stands for vascular endothelial growth factor. It is a protein your body produces naturally. In the eye, too much VEGF can cause blood vessels in the retina to leak fluid or grow in places they should not. This leaking and abnormal growth damages the retina, the light-sensitive tissue at the back of the eye, and can lead to vision loss.
Conditions driven by excess VEGF include wet age-related macular degeneration (wet AMD), diabetic macular edema (DME), and macular edema from retinal vein occlusions. Approximately 19.8 million Americans aged 40 and older were living with some form of age-related macular degeneration in 2019, with 1.49 million having vision-threatening late-stage disease (CDC, 2019). Diabetic macular edema affects about 3.8 percent of U.S. adults aged 40 and older with diabetes (NIH, 2015).
Anti-VEGF medications are injected directly into the eye to block VEGF before it can cause harm. By neutralizing VEGF, these drugs reduce fluid leakage from damaged blood vessels. They also decrease swelling in the macula (the central part of the retina responsible for sharp vision). These medications slow or stop the growth of abnormal new vessels.
Think of VEGF as a signal telling blood vessels to leak. Anti-VEGF medications intercept that signal. When the signal is blocked, the retina can begin to dry out. Vision may then stabilize or improve over time.
Eye drops and oral medications cannot deliver enough drug to the retina to be effective against these conditions. An intravitreal injection (an injection directly into the gel-filled space inside the eye) places the medication exactly where it is needed. The injection itself takes only seconds. The medication works at the site of disease for weeks before the body gradually breaks it down.
Aflibercept (Eylea): A Closer Look
Aflibercept, sold under the brand name Eylea, is a fully human recombinant fusion protein designed specifically for use in the eye. It works as a VEGF trap, meaning it binds tightly to VEGF-A (all forms), VEGF-B, and placental growth factor (PlGF). By capturing these proteins, aflibercept prevents them from activating receptors on blood vessel cells. This stops the leaking and abnormal vessel growth that threaten vision.
Eylea has FDA approval for several retinal conditions. These include wet AMD, diabetic macular edema (approved 2014), diabetic retinopathy, and macular edema following retinal vein occlusion. It is one of the most widely prescribed anti-VEGF medications in the world.
Eylea (2 mg) is typically given as a series of monthly injections for the first three to five doses. This initial phase is called the loading dose period. After that, injections are often extended to every eight weeks for most conditions. Many retina specialists use a treat-and-extend approach. This means they gradually increase the time between injections as long as the eye remains stable.
In August 2023, the FDA approved Eylea HD (high-dose aflibercept, 8 mg), a higher-dose formulation that allows for longer intervals between injections. After loading doses, Eylea HD can be given every 8 to 16 weeks initially. Data from the PULSAR and PHOTON clinical trials showed that 71 percent of wet AMD patients and 72 percent of DME patients maintained intervals of 16 weeks or longer at 96 weeks (FDA, 2023). Some patients may eventually extend to intervals as long as 20 weeks.
Bevacizumab (Avastin): A Closer Look
Bevacizumab, sold under the brand name Avastin, is a humanized monoclonal antibody that binds to and neutralizes all forms of VEGF-A. This prevents VEGF-A from interacting with receptors on blood vessel cells. The result is reduced leaking and abnormal vessel growth in the retina.
Avastin was originally developed and FDA-approved for the treatment of certain cancers. It is used off-label for eye conditions, meaning the FDA has not approved it specifically for ophthalmic use. Despite this, it is one of the most commonly used anti-VEGF agents for retinal diseases worldwide. The dose used in the eye (1.25 mg) is a small fraction of the dose used for cancer treatment.
Avastin is widely used for retinal conditions in part because it has a long track record of clinical evidence supporting its effectiveness. Large studies, including the CATT trial, have compared it directly to FDA-approved alternatives and found similar visual outcomes for many patients. It is available at a lower per-dose amount than some other anti-VEGF agents, which has contributed to its widespread adoption. Many retina specialists consider it a well-established first-line treatment for conditions like wet AMD and DME.
Using a medication off-label means a doctor prescribes it for a purpose other than its FDA-approved indication. Off-label use is legal and common across many areas of medicine. However, Avastin has not gone through the same FDA review process for eye use that Eylea has. Large clinical trials have studied Avastin for retinal conditions. Retina specialists consider it a well-established treatment option based on extensive real-world experience and research data.
Comparing Eylea and Avastin
The DRCR Retina Network Protocol T study compared aflibercept, bevacizumab, and ranibizumab for treating diabetic macular edema. In eyes that started with worse vision (20/50 or worse), aflibercept provided superior results. Patients in the aflibercept group gained an average of 18.1 letters of vision at two years, compared to 13.3 letters for bevacizumab (DRCR Retina Network, Protocol T). In eyes that started with better vision, the outcomes were similar among all three drugs.
Some patients who begin treatment with Avastin may later switch to Eylea if their response is not adequate. The DRCR Retina Network Protocol AC trial found that 70 percent of eyes in a bevacizumab-first treatment group required switching to aflibercept within two years when treating diabetic macular edema (NEJM, 2022). This suggests that while Avastin is a reasonable starting point, a meaningful number of patients may eventually benefit from a different anti-VEGF agent.
Research suggests that aflibercept may allow more patients to reduce or pause treatment over time. One study found that 43 percent of patients on aflibercept were successfully paused at one year, compared to 15 percent on bevacizumab (DRCR Retina Network, Protocol T). The higher-dose Eylea HD formulation further extends the time between injections for many patients. This can reduce the overall treatment burden.
There are several practical differences between these two medications that patients should understand.
- Eylea is FDA-approved for multiple retinal conditions. Avastin is used off-label for eye conditions.
- Eylea binds VEGF-A, VEGF-B, and placental growth factor. Avastin binds only VEGF-A.
- Eylea injections are typically spaced every 4 to 8 weeks after loading doses. Avastin is commonly given every 4 to 6 weeks.
- Eylea HD (8 mg) may allow intervals of 16 to 20 weeks for eligible patients.
What to Expect During Treatment
Your retina specialist will dilate your pupil and numb the eye with anesthetic drops. The surface of the eye and eyelids are cleaned with an antiseptic solution to reduce the risk of infection. The entire preparation typically takes longer than the injection itself. You may be asked to look in a specific direction to help position the eye.
The injection is given through the white part of the eye (the sclera) using a very fine needle. Most patients feel a brief pressure sensation. The procedure takes only a few seconds. Some patients report mild discomfort, and it is normal to feel a stinging or burning sensation for a short time afterward. Numbing drops help manage this, but the experience is not entirely without sensation.
It is common to see floaters, have mild redness at the injection site, or notice a slightly gritty feeling for a day or two. Your retina specialist may check your eye pressure before you leave. Most people can return to normal activities the same day. You may be advised to avoid rubbing your eye and to use prescribed antibiotic drops for a few days.
Anti-VEGF treatment for most retinal conditions is ongoing. The goal is to find the longest interval between injections that keeps the disease stable. Some patients receive injections for years. Others may be able to extend intervals significantly or take a monitored break from treatment. Your retina specialist will use imaging tests at each visit to guide these decisions.
Living With Anti-VEGF Treatment
Keeping up with injection appointments is one of the most important things a patient can do. Missing or delaying treatments can allow the disease to become active again, sometimes causing irreversible vision loss. If scheduling is difficult, discuss this with your retina specialist. Newer formulations like Eylea HD may help reduce the frequency of visits for eligible patients.
Between appointments, pay attention to any changes in your vision. Using an Amsler grid (a simple printed chart with a grid pattern) daily can help you notice new distortion or blank spots. Report any changes to your retina specialist promptly rather than waiting for your next scheduled visit.
For patients with diabetic macular edema, managing blood sugar, blood pressure, and cholesterol can support the effectiveness of anti-VEGF treatment. Research shows that each 1 percent increase in HbA1c (a measure of long-term blood sugar control) raises DME risk by 47 percent (NIH, 2015). For patients with wet AMD, quitting smoking, eating a diet rich in leafy greens and fish, and maintaining a healthy weight may help slow disease progression alongside injection therapy.
Risks and Side Effects
The most common side effects of intravitreal injections are mild and temporary. They include eye redness at the injection site, floaters, mild eye discomfort or a scratchy sensation, and a small red spot on the white of the eye (subconjunctival hemorrhage). These typically resolve on their own within a few days.
Serious complications from intravitreal injections are uncommon but important to understand. Endophthalmitis (a severe infection inside the eye) occurs in fewer than 1 in 1,000 injections when proper sterile technique is used (AAO, 2023). Retinal detachment, significant bleeding inside the eye, and sustained high eye pressure are other rare risks. There is also a small theoretical risk of blood clots, stroke, or heart attack with anti-VEGF agents. Large studies have not shown a significant difference in these events between anti-VEGF drugs and control groups.
When to See a Retina Specialist
Contact your retina specialist or go to the emergency room immediately if you experience any of the following after an injection: severe eye pain that worsens rather than improves, significant vision loss or a sudden change in vision, increasing redness or discharge from the eye, extreme sensitivity to light, or new flashes of light or a sudden increase in floaters. These symptoms could indicate a rare but serious complication that requires prompt treatment.
Between scheduled visits, see your retina specialist promptly if you notice new distortion of straight lines or a dark area appearing in your central vision. Difficulty reading or recognizing faces that was not present before also warrants evaluation. Any worsening of vision between treatments should be assessed. It may mean the disease has become more active and your treatment plan needs adjustment.
Questions and Answers
Avastin (bevacizumab) has been studied in large, well-designed clinical trials for retinal conditions, including the landmark CATT and DRCR Retina Network studies. These trials found it to be effective and to have a safety profile similar to FDA-approved anti-VEGF agents when prepared and administered properly. However, because it is used off-label, it does not carry the same regulatory oversight for ophthalmic use. Your retina specialist can discuss the benefits and risks specific to your situation.
Not all eyes respond equally to every anti-VEGF medication. If fluid or swelling in the retina persists despite consistent Avastin treatment, your retina specialist may recommend switching to Eylea or another agent. Research from the DRCR Protocol AC trial showed that 70 percent of patients starting on bevacizumab for diabetic macular edema required a switch to aflibercept within two years (NEJM, 2022). A switch does not mean the first medication failed entirely. It means a different drug may work better for your specific disease.
The number of injections varies widely depending on the condition being treated, its severity, and how your eye responds. Most patients start with a series of monthly loading doses (typically three to five), followed by injections at gradually increasing intervals. Some patients may need ongoing injections for years. Others may achieve stable intervals of three to five months, especially with newer formulations like Eylea HD. Your retina specialist will tailor the schedule based on imaging and exam findings at each visit.
Anti-VEGF treatment can improve vision in many patients, particularly those who begin treatment before extensive retinal damage has occurred. Clinical trials have shown meaningful gains in visual acuity for many participants. However, the degree of improvement depends on factors like how long the condition has been present and how much damage the retina has sustained. The primary goal of treatment is to stabilize vision and prevent further loss. Improvement is an important but not certain additional benefit.
Most patients experience some discomfort rather than sharp pain. Numbing drops are applied before the injection, and the needle used is extremely fine. Many people describe feeling brief pressure or a mild stinging sensation. Anxiety about the procedure is very common, especially before the first injection. Most patients report that the anticipation is worse than the actual experience. If you are concerned about discomfort, discuss additional comfort measures with your retina specialist.