Avastin Eye Injection: Procedure, Uses, and Aftercare

Bevacizumab, sold under the brand name Avastin, is one of the most commonly administered eye injections in the world, used to treat conditions where abnormal blood vessels grow in or leak fluid into the retina. Originally developed as a cancer drug, it works by blocking a protein called vascular endothelial growth factor (VEGF) that drives the growth of these rogue vessels. The injection itself takes only seconds, but it sits at the center of a larger story involving off-label use, cost savings, ongoing treatment schedules, and a set of aftercare practices that genuinely matter for outcomes.

How Avastin Works in the Eye

The retina needs a steady blood supply, but sometimes the body produces too much VEGF in response to poor oxygen delivery or other disease processes. That excess VEGF triggers the growth of fragile new blood vessels that leak fluid and blood into the macula, the part of the retina responsible for sharp central vision. A landmark finding in the mid-1990s established that oxygen-starved retinal tissue produces VEGF, linking the protein directly to destructive vessel growth in the eye.¹ Bevacizumab binds to VEGF and neutralizes it, which slows or stops the leaking and abnormal growth. Injected directly into the vitreous gel of the eye, the drug reaches the retina in high concentration without flooding the rest of the body.

Conditions Treated with Avastin Injections

Avastin is used across several retinal diseases, all of which share the common thread of VEGF-driven damage.

Wet Age-Related Macular Degeneration

Wet AMD is the condition most people associate with Avastin eye injections. In wet AMD, abnormal blood vessels grow beneath the retina and leak, causing rapid central vision loss. A systematic review covering hundreds of patients found that bevacizumab consistently improved visual acuity in wet AMD across multiple studies.² A Romanian cohort study spanning over a decade of experience reported that about two-thirds of treated eyes showed improved visual acuity at three months, with measurable reductions in macular thickness on imaging.³

Diabetic Macular Edema

Diabetes can cause fluid to accumulate in the macula, blurring vision even when blood sugar is reasonably controlled. Avastin injections reduce that swelling. In one study of patients with diabetic macular edema, macular thickness dropped meaningfully in about four out of five eyes within a month of a single injection.⁴ Even in patients with persistent swelling who had already failed other treatments like laser photocoagulation or steroid injections, bevacizumab still produced improvements in both visual acuity and retinal thickness.⁵ A Ugandan cohort found that roughly 69% of eyes improved from baseline, with particularly strong results in diabetic patients.⁶

Retinal Vein Occlusion

When a vein in the retina becomes blocked, the resulting backup of blood and fluid causes swelling and vision loss. Bevacizumab has been shown to significantly improve both visual acuity and retinal thickness in branch retinal vein occlusion, with improvements lasting several months after treatment.⁷

What the Injection Procedure Feels Like

The idea of a needle going into your eye sounds far worse than the reality, though that probably does not fully reassure you the first time. The procedure typically takes place in an exam chair, not an operating room. Your eye doctor will use numbing drops or a small anesthetic injection around the eye, so you feel pressure rather than sharp pain. The skin around your eye is cleaned with an iodine-based antiseptic solution, and a small speculum holds your eyelids open. The injection itself uses a very fine needle inserted through the white part of the eye into the vitreous cavity. It is over in a few seconds.

Immediately after, you may see floaters or have mildly blurred vision, which usually clears within a day. The pressure inside the eye spikes briefly from the added fluid volume. One study found that eye pressure rose to an average of about 36 mmHg at three minutes post-injection (normal is roughly 10 to 21) but fell on its own to below 30 in every patient within 15 minutes.⁸ Your doctor will likely check that pressure before you leave, and the whole visit usually wraps up in under an hour.

Aftercare That Actually Matters

Most aftercare guidance centers on infection prevention and watching for warning signs. The injection site creates a tiny entry point for bacteria, and the most serious risk in the first few days is endophthalmitis, an infection inside the eye. Here is what you should and should not do after an Avastin injection:

Avoid rubbing your eye for at least a day or two. Touching introduces bacteria.
Use prescribed drops as directed. Many doctors prescribe antibiotic drops for a few days, though practice varies. Follow your doctor’s specific instructions.
Skip swimming and hot tubs for at least a week. Water carries bacteria that you do not want near a fresh injection site.
Watch for warning signs in the first few days: increasing pain, worsening redness, significant vision loss, or sensitivity to light. These can signal endophthalmitis and warrant emergency contact with your eye doctor.
Expect mild discomfort such as scratchiness, slight redness, or a small spot of blood on the white of the eye. These are normal and resolve on their own.

About 42% of patients report some restriction from normal activities due to discomfort after the procedure, though overall satisfaction with treatment tends to be high.⁹ Half of patients said they experienced side effects on more than half their visits, but these were generally mild enough that people continued treatment willingly.

Risks and Complications

The most feared complication is endophthalmitis. A meta-analysis pooling data from over 105,000 anti-VEGF injections found that the rate of infection was about 0.05%, or roughly 1 in 2,000 injections.¹⁰ When it does occur, the most common culprit is a skin bacterium called coagulase-negative Staphylococcus, which accounted for about two-thirds of culture-positive cases. Streptococcus species, likely from mouth or respiratory droplets, were found in about a third of positive cultures, which is roughly three times more frequent than after conventional eye surgery. That finding is why many clinics ask both the doctor and the patient to wear masks or at least avoid talking during the injection.

Case reports of endophthalmitis exist in the literature, including patients who needed emergency surgery with intravitreal antibiotics to save the eye.¹¹ One series pegged the incidence of culture-proven endophthalmitis at about 0.066%.¹² The good news is that when caught early, many patients recover meaningful vision.

Eye Pressure Changes Over Time

Beyond the immediate spike that resolves in minutes, repeated injections can lead to sustained increases in eye pressure in a subset of patients. One study found that after multiple bevacizumab injections, about a third of eyes showed elevated pressure above their starting baseline, and the total number of injections was the strongest predictor of sustained elevation.¹³ A smaller case series documented six patients who developed significant, persistent pressure elevation requiring glaucoma-lowering eye drops after bevacizumab injections.¹⁴ If you have glaucoma or are at risk for it, your doctor should be monitoring your eye pressure closely at each visit.

Systemic Side Effects

Because only a tiny amount of bevacizumab enters the bloodstream from an eye injection, systemic side effects are uncommon. A systematic review covering nearly 13,000 patients found that the most frequently reported systemic event was a rise in blood pressure, occurring in less than half a percent of patients. Stroke and heart attack were reported even less often, at roughly 0.2% each.¹⁵ These events are the kind of thing VEGF-blocking drugs can cause in theory, since VEGF plays a role in maintaining healthy blood vessels throughout the body, but a direct causal link from eye injections has not been firmly established. Patients with existing cardiovascular risk factors should discuss them with their eye doctor.

Why Avastin Is Used Off-Label and What That Means

Avastin was approved by regulators for treating certain cancers, not eye disease. Its use in the eye is “off-label,” which means doctors are prescribing it for a purpose not included in the official label. This sounds alarming but is standard medical practice when strong evidence supports the use. In this case, the evidence is overwhelming, with thousands of published studies and millions of injections worldwide.

The reason Avastin became so popular in ophthalmology comes down to cost. Ranibizumab (Lucentis) and aflibercept (Eylea) were specifically developed and approved for eye use, but they cost dramatically more per dose. A cost-effectiveness analysis found that ranibizumab costs up to 100 times more than bevacizumab per injection, and that the price of ranibizumab would need to be drastically reduced for it to be cost-effective by standard health-economics thresholds.¹⁶ One U.S. analysis estimated that increasing bevacizumab’s market share by just 10% would save Medicare roughly $468 million and patients about $119 million.¹⁷

Because Avastin is not packaged for eye use, it must be split from a larger cancer-treatment vial into smaller doses by a compounding pharmacy. That repackaging step introduces a risk: if sterility is compromised, contamination can cause clusters of infections. A 2023 outbreak in Punjab, Pakistan, where 66 patients suffered vision loss, was traced to improper repackaging and handling outside sterile conditions.¹⁸ Events like this are rare, but they underscore why your clinic’s compounding source matters. Reputable eye centers use certified compounding pharmacies that follow strict sterility standards.

How Avastin Compares to Approved Alternatives

The question patients and health systems both ask is whether the cheaper drug works as well as the more expensive ones. The answer depends on the condition and the severity of vision loss at the start of treatment.

For diabetic macular edema, a large comparative effectiveness trial found that at two years, patients gained an average of about 10 letters on a vision chart with bevacizumab, compared with roughly 13 for aflibercept and 12 for ranibizumab. When patients started with relatively mild vision loss, the three drugs performed similarly. But among patients who started with worse vision (20/50 or worse), aflibercept produced a meaningfully larger gain than bevacizumab.¹⁹

For central retinal vein occlusion, a three-arm trial found that aflibercept was statistically non-inferior to ranibizumab at 100 weeks, but bevacizumab could not meet the non-inferiority threshold compared with ranibizumab. The actual differences were modest: bevacizumab patients gained about 10 letters on average compared with about 13 for ranibizumab and 15 for aflibercept. Aflibercept also required fewer injections over the study period.²⁰

So the picture is nuanced. Bevacizumab works well for most people, but in certain situations—particularly when starting vision is poor or the disease involves central vein occlusion—the approved alternatives may offer a modest edge. For many patients and health systems, the enormous cost savings make bevacizumab the practical first choice, with a switch to aflibercept or ranibizumab reserved for cases that do not respond adequately.

Treatment Schedules and How Long You Will Need Injections

This is the part patients tend to find most daunting: Avastin is not a one-time treatment. Most conditions that call for it are chronic, and the drug wears off within a month or two. Initially, you will likely receive monthly injections for three to six months (a “loading phase”), after which your doctor assesses response and adjusts the interval.

The two main scheduling approaches are monthly dosing and “treat-and-extend.” In monthly dosing, you get an injection every four weeks regardless. In treat-and-extend, the interval between injections is gradually stretched as long as the disease stays quiet. Two randomized trials comparing these approaches found that treat-and-extend produced similar visual outcomes with meaningfully fewer injections, roughly 9 per year instead of 11 or 12.²¹ A secondary analysis from the SCORE2 trial similarly showed that good responders could switch to treat-and-extend dosing and receive one to two fewer injections over six months without meaningful vision differences.²²

Some patients eventually achieve long remissions and can stop injections entirely, while others need them indefinitely. Your doctor will use imaging scans at each visit to decide whether to extend, maintain, or shorten the interval between treatments.

Dealing with Injection Anxiety

Getting a needle in your eye regularly is psychologically challenging, and studies confirm that anxiety is a real and common part of the experience. A review of the literature found that pre-procedural anxiety was reported by anywhere from 17% to 85% of patients, typically at mild-to-moderate levels.²³ Key drivers included lack of information about the procedure, discomfort during or after, and the logistical burden of frequent clinic visits.

The encouraging finding across multiple studies is that anxiety tends to decrease with experience. One study found a significant negative correlation between the number of previous injections and anxiety scores, meaning the more injections you have had, the less anxious you tend to be.²⁴ Younger patients tended to report higher anxiety than older patients, possibly because older patients may have had more medical experiences or feel more urgency about preserving their vision. Another survey found that patients who had received fewer than five injections were significantly more anxious before, during, and after the procedure compared with those who had received more than 50.⁹

If you are anxious about your first injection, it helps to know that most people describe the actual sensation as mild pressure rather than pain, and the anticipation is almost always worse than the event itself. Asking your doctor to explain each step as it happens can reduce the feeling of helplessness.

Avastin in Premature Infants

One population that might surprise readers is premature babies. Retinopathy of prematurity (ROP) occurs when abnormal blood vessels grow in the retinas of very early newborns, and severe cases can cause blindness. Bevacizumab has become an alternative to traditional laser therapy for the most dangerous forms of this disease.

A pivotal trial published in the New England Journal of Medicine found that bevacizumab significantly reduced recurrence of the disease compared with laser treatment in the most severe zone of the retina. Recurrence occurred in only 4% of bevacizumab-treated eyes versus 22% of laser-treated eyes.²⁵ Another study found that after a single bevacizumab injection, the disease regressed with complete or near-complete retinal blood vessel development in about 83% of eyes, rising to 93% after up to two injections, with no major complications.²⁶

There are trade-offs, though. Unlike laser, which permanently scars the peripheral retina and stops abnormal vessels from growing back, bevacizumab wears off. That means the disease can reactivate weeks or months later, requiring close follow-up and sometimes additional treatment. A study tracking outcomes at 12 months noted that while poor retinal outcomes were uncommon at 3%, strabismus was present in about 29% of infants, though disentangling what was caused by the drug versus the underlying prematurity is difficult.²⁷ There is also theoretical concern about systemic VEGF suppression in a developing infant, since VEGF is important for normal organ growth. Ongoing research is investigating whether lower doses of bevacizumab can achieve the same retinal benefit while minimizing systemic exposure.

The Push for Longer-Lasting Treatments

The treatment burden of repeated injections, sometimes monthly for years, is the single biggest complaint patients have. Researchers and pharmaceutical companies are actively working on sustained-release delivery systems that could maintain anti-VEGF drug levels in the eye for months from a single administration. These range from biodegradable polymer implants placed inside the eye to port delivery systems that act as tiny refillable reservoirs. The goal is to reduce the number of clinic visits while keeping the disease under control.²⁸ Some newer anti-VEGF drugs with longer half-lives have already reached the market, allowing injection intervals of two to four months in certain patients. Whether these will eventually make the monthly injection cycle obsolete remains to be seen, but the trajectory is clearly toward less frequent treatment.