Common and Serious Eylea Injection Side Effects

Eylea (aflibercept) is one of the most widely used eye injections for conditions like wet age-related macular degeneration, diabetic macular edema, and retinal vein occlusion, and its most common side effects are mild and short-lived: small bleeds on the white of the eye, temporary eye pain, and floaters. Serious complications do exist but are rare, with infections occurring in fewer than 1 in 2,000 injections and sustained pressure elevation developing in a small fraction of patients over long-term treatment. The picture gets more interesting when you look at how the drug interacts with eye pressure in the minutes after each shot, what happens to the cornea over years of repeated injections, and whether blockage of a growth factor inside the eye can ripple out to the rest of the body.

How the Injection Works

Aflibercept is a lab-made fusion protein that acts as a decoy receptor, latching onto vascular endothelial growth factors A and B as well as placental growth factor and preventing them from triggering abnormal blood vessel growth and leakage in the retina.¹ A tiny volume of fluid is injected directly into the vitreous, the gel-like interior of the eye, using a fine-gauge needle. That delivery method is responsible for many of the side effects people experience: the needle passes through the conjunctiva and sclera, and the added fluid briefly changes the pressure dynamics inside the eye. Understanding this helps separate the side effects that come from the drug itself from those that come from the act of putting a needle in your eye.

Common, Mild Side Effects

The side effects most people notice are the least dangerous. Subconjunctival hemorrhage, the small red blotch where the needle entered, is the most frequent. It looks alarming but is painless and resolves on its own within a week or two. Eye pain, typically described as a gritty or aching sensation, tends to peak in the hours after injection and fades within a day. Floaters can appear or temporarily worsen because the injected solution mixes with the vitreous gel. Some patients report increased tearing or a foreign-body sensation for a few hours. Clinical trials have consistently found that aflibercept is generally well tolerated, and these nuisance-level effects are the ones that account for most reported events.²

The Immediate Pressure Spike

Injecting even a small volume of liquid into a closed space raises the pressure inside that space, and the eye is no exception. One study measuring intraocular pressure (IOP) at precise intervals found that pressure jumped dramatically within the first minute: the average reading went from about 15 mmHg before the shot to roughly 37 mmHg one minute after. Nearly half the patients hit 40 mmHg or higher, and more than three-quarters exceeded 30 mmHg in that first minute.³ Those numbers sound high, and they are, but the spike is transient. By 20 minutes post-injection, mean pressure was back down to about 17 mmHg in the same study.

A separate study looking at pressure six hours later found that the residual difference was less than 1 mmHg above pre-injection levels, and this held for both patients with their natural lens and those who had previously had cataract surgery.⁴ For most people, the eye’s natural drainage handles the extra fluid quickly. The concern is greatest in patients who already have glaucoma or borderline-high eye pressure, where even a brief spike can potentially cause damage.

Sustained Pressure Elevation with Repeated Injections

The short-lived spike is one thing. A more troubling pattern is a sustained rise in baseline eye pressure that develops after many injections over months or years. A systematic review and meta-analysis of randomized trials found that patients receiving repeated anti-VEGF injections had roughly three times the risk of sustained pressure elevation compared to those receiving sham injections or laser treatment. The risk grew with longer follow-up: it was about twice baseline risk at six months and more than three times at around two years.⁵ In practical terms, this affects a minority of patients. One clinical series found that 4 out of 58 patients treated with recurring Eylea or bevacizumab injections developed prolonged pressure elevation requiring ongoing pressure-lowering eye drops.⁶ Your retina specialist will typically check your eye pressure at each visit and can catch this trend early.

Infection Inside the Eye

Endophthalmitis, an infection of the interior of the eye, is the side effect retina doctors worry about most because it can threaten vision permanently. The good news is that it is genuinely rare. A large retrospective study found the overall rate of endophthalmitis across all anti-VEGF injections was about 0.035%, or roughly 1 case for every 2,857 injections. For aflibercept specifically, the rate was 0.037%, essentially the same as for ranibizumab and bevacizumab.⁷ Another large dataset placed the rate for aflibercept at a similar 0.035%, with no statistically significant difference between the three drugs.⁸

Because each injection carries its own small risk, the cumulative likelihood rises the more injections you receive. A registry analysis found the cumulative rate of infectious endophthalmitis per patient climbed from about 0.31% after 10 injections to 0.58% after 60 injections.⁹ Patients undergoing long-term treatment should be aware that the per-injection odds stay low, but the lifetime exposure adds up. Warning signs include sudden onset of eye pain, rapid vision loss, and increasing redness a few days after the injection. If any of these appear, contact your eye doctor immediately; early treatment makes a substantial difference in outcomes.

How Antiseptic Technique Lowers Infection Risk

The single biggest modifiable factor in endophthalmitis prevention is the antiseptic applied to the eye surface before the needle goes in. Povidone-iodine (the brownish disinfectant) is the standard. One study found that reapplying povidone-iodine after inserting the lid speculum dropped the endophthalmitis rate dramatically compared to a single application before the speculum went in.¹⁰ Some clinics have experimented with chlorhexidine-alcohol as an alternative, but a comparative study showed the endophthalmitis rate was about three times higher with chlorhexidine than with povidone-iodine.¹¹ If your doctor uses povidone-iodine with proper re-application technique, you are getting the lowest-risk prep currently supported by evidence.

Sterile Inflammation

Not every inflammatory reaction after an Eylea injection means infection. Sterile inflammation, where the eye becomes inflamed without any bacteria involved, can mimic early endophthalmitis and create real anxiety. A Korean study identified four cases of sterile inflammation out of 723 aflibercept injections, putting the per-injection rate at about 0.55%. Every case involved blurred vision without pain, and all patients recovered their pre-injection vision within about three weeks on average.¹² A larger study across multiple drugs found the rate of noninfectious vitritis (inflammation of the vitreous) was 0.16% for aflibercept, somewhat higher than for ranibizumab but in the same general range as bevacizumab.¹³ The key distinction for patients: sterile inflammation tends to be painless and resolves with steroid eye drops, while true endophthalmitis typically involves pain and worsens without intervention.

Retinal Vasculitis and the Higher-Dose Formulation

In 2023, a higher-dose version of aflibercept (8 mg instead of the standard 2 mg) was approved to extend the time between injections. Its overall safety profile in a phase 2 trial looked similar to the 2 mg dose, with no new safety signals over 44 weeks.¹⁴ However, post-marketing pharmacovigilance data have raised a signal worth watching. An analysis of the FDA’s adverse event reporting system found that aflibercept 8 mg had a substantially higher reporting odds ratio for retinal vasculitis compared to the 2 mg dose.¹⁵ Pharmacovigilance data have real limitations: higher reporting rates for a newer product can reflect heightened awareness rather than higher true incidence. But the signal was large enough to prompt ongoing monitoring. If you are on the 8 mg formulation, this does not mean you should switch, but it means your doctor should be attentive to any unusual visual symptoms between visits.

Retinal Detachment

Rhegmatogenous retinal detachment, the type caused by a tear in the retina, is a feared complication of any procedure that involves putting a needle through the eye wall. A systematic review and meta-analysis spanning nearly 800,000 injections found the pooled risk was about 0.012%, or roughly 1 in 8,675 injections.¹⁶ When they restricted the analysis to detachments occurring within 90 days of injection, the rate was nearly identical. These numbers are reassuring: the risk exists, but it is extremely low and is a function of the needle procedure itself rather than the drug.

Blood Pressure During the Procedure

Getting a needle in the eye is stressful, and the body responds. A study measuring blood pressure before, during, and after the injection procedure found that mean systolic blood pressure rose from 150 mmHg at baseline to 168 mmHg during injection. About 11% of patients spiked above 200 mmHg systolic, with that subgroup averaging a jump of 32 mmHg.¹⁷ This is driven by anxiety and the fight-or-flight response, not by the drug itself. For most people the spike is harmless and brief. For patients with poorly controlled hypertension or a history of stroke, it is worth discussing with both the retina specialist and the primary care doctor, particularly if injections are happening monthly.

Systemic Side Effects Beyond the Eye

Blocking VEGF inside the eye raises a reasonable question: does the drug leak into the bloodstream and affect the rest of the body? After an Eylea injection, plasma VEGF levels drop significantly. One trial found that a week after injection, detectable VEGF had fallen below the minimum measurable level in nearly 90% of patients, and the reduction persisted for at least a month.¹⁸ That is a real systemic effect, and it raises the theoretical concern of cardiovascular events, since VEGF plays a role in blood vessel maintenance throughout the body.

In practice, the cardiovascular signal has been hard to pin down. A large U.S. cohort study comparing new users of aflibercept and ranibizumab found no increased risk of heart attack, stroke, or death with aflibercept. There was a small, borderline-significant elevation in stroke risk among patients with diabetic macular edema, but the confidence interval just barely crossed statistical significance.¹⁹ A population-based cohort study in Taiwan similarly found no overall difference in arterial thromboembolic risk between aflibercept and ranibizumab over two years, and in some subgroups, aflibercept patients actually had lower risk.²⁰

When all three major anti-VEGF drugs were compared head to head in routine clinical practice, event rates for heart attack, stroke, major bleeding, and hospitalization were essentially the same across aflibercept, ranibizumab, and bevacizumab over 180 days.²¹ A randomized comparative effectiveness trial in diabetic macular edema found that vascular events (heart attack, stroke, and related events) occurred in 5% of the aflibercept group over two years, lower than the 8% for bevacizumab and 12% for ranibizumab, though the statistical significance of those differences depended on adjustments for confounders.²² The weight of evidence suggests that cardiovascular risk from Eylea injections, if it exists at all, is small and difficult to separate from the already elevated baseline risk in the elderly population that receives these drugs.

Geographic Atrophy Progression

Geographic atrophy is a form of advanced dry macular degeneration characterized by irreversible loss of retinal cells. There is a persistent and somewhat unsettling question in the field: does long-term anti-VEGF treatment itself accelerate the development of geographic atrophy? A review of histopathologic, animal, and clinical evidence concluded that there are emerging signals pointing toward this possibility, though direct proof has not been established.²³ More concretely, a study examining geographic atrophy incidence across different treatment regimens found a moderate positive correlation between the total number of injections and the development of atrophy. Monthly treatment schedules were associated with about a 40% higher risk of developing geographic atrophy compared to as-needed dosing.²⁴

This creates a genuine clinical tension. Patients need regular injections to prevent vision loss from wet macular degeneration, but more frequent injections may contribute to a different form of retinal damage over time. It is one reason many retina specialists favor treat-and-extend protocols, stretching the interval between injections as long as the retina remains stable, rather than rigid monthly dosing. The data on this topic are still evolving, and no one is suggesting patients should skip injections out of fear of atrophy. But it is a factor that informs how doctors choose your treatment schedule.

What Happens to the Cornea Over Time

Each injection passes through the outer layers of the eye, and there has been interest in whether repeated needle punctures and the drug itself affect the corneal endothelium, the single layer of cells that keeps the cornea clear. A six-month study found no significant changes in endothelial cell density or corneal thickness after aflibercept injections, though one measure of maximum cell size did shift slightly.²⁵ Over longer timeframes, the picture is a bit different. A study using regression analysis found that both age and the total number of injections were independently associated with lower endothelial cell density and less regular cell shape.²⁶ Another study confirmed that repeated injections of either ranibizumab or aflibercept can influence corneal endothelial cell morphology, though they did not change corneal thickness.²⁷

For most patients, these corneal changes are subclinical, meaning you would not notice them and they would not affect your vision. They matter more for patients who already have compromised corneal endothelial health, such as those with Fuchs’ dystrophy, and for anyone facing the prospect of many years of injections. The cornea does not regenerate endothelial cells the way skin heals a cut, so cumulative losses over decades of treatment are worth tracking.

Pregnancy and Eylea

VEGF is critical for normal blood vessel development in a growing fetus, which makes any VEGF-blocking drug a concern during pregnancy. A case series and literature review noted that while intravitreal anti-VEGF injections are sometimes used off-label in pregnant women with vision-threatening conditions, the drugs may cause systemic effects in the mother and potential harm to the fetus. The authors concluded that these injections should be given during pregnancy only when the potential benefit to the woman justifies the risk.²⁸ Because the typical Eylea patient is older, pregnancy rarely comes up, but it is relevant for younger women being treated for conditions like diabetic retinopathy or myopic choroidal neovascularization. If you are of childbearing age and receiving Eylea, effective contraception during treatment is generally recommended.