Bevacizumab, known as Avastin, is a medication administered directly into the eye via an intravitreal injection. This treatment manages and stabilizes vision loss caused by several serious eye conditions. The drug is a humanized monoclonal antibody that targets a specific growth factor. By introducing Avastin into the vitreous—the clear, jelly-like substance in the back of the eye—specialists address the underlying causes of vision deterioration. The goal is to preserve the patient’s existing sight and prevent further damage from abnormal vascular changes in the retina.
Mechanism of Action and Clinical Applications
Avastin’s therapeutic effect is based on blocking Vascular Endothelial Growth Factor (VEGF). VEGF is a signaling protein that stimulates the growth of new blood vessels (angiogenesis) and increases the permeability of existing vessels. In certain eye diseases, the retina produces excessive VEGF, leading to the growth of fragile, abnormal blood vessels or causing existing vessels to leak fluid and blood.
Avastin is classified as an anti-VEGF agent because it binds to all active forms of the VEGF-A protein. By attaching to VEGF-A, Avastin prevents the protein from docking onto its receptors on endothelial cells. This blockage stops the signaling pathway that causes the proliferation of abnormal, leaky blood vessels behind the retina. The resulting effect is a reduction in fluid leakage and swelling in the macula, the central part of the retina responsible for sharp, detailed vision.
This mechanism treats conditions characterized by macular edema or neovascularization. Clinical applications include wet Age-Related Macular Degeneration (AMD), where abnormal vessels grow under the macula. It is also used for Diabetic Macular Edema (DME), which is swelling caused by damaged blood vessels in diabetic patients. Additionally, Avastin treats vision loss resulting from macular edema secondary to Retinal Vein Occlusion (RVO).
Preparing for and Receiving the Injection
Receiving an intravitreal Avastin injection is a quick, in-office procedure performed in a sterile environment. The specialist first ensures patient comfort and a sterile field. This begins with applying topical anesthetic drops, and sometimes a small numbing injection, to ensure the eye is without sensation.
Once the eye is numb, the area is thoroughly cleaned with an antiseptic solution, typically povidone-iodine, to minimize infection risk. An eyelid speculum is often used to gently hold the eyelids open and prevent blinking. The injection is administered using a very fine needle, which passes through the sclera (the white part of the eye) into the vitreous cavity.
The actual injection takes only a few seconds. Most patients report feeling only pressure, not pain, due to the anesthesia. Afterward, the speculum is removed, and an antibiotic drop or ointment may be applied as a precaution. Patients may experience temporary, mild side effects, such as seeing small floaters or bubbles, which typically resolve within a few days. Patients should avoid swimming or rubbing the eye for a few days after the procedure.
Safety Profile, Risks, and Off-Label Status
Avastin is considered safe and effective, but like any medical procedure, it carries risks. Common minor side effects include temporary eye irritation, a scratchy sensation, and subconjunctival hemorrhage (a harmless red spot caused by a small broken blood vessel). These minor issues usually resolve within one to two weeks.
The most serious, though very rare, risks associated with any intravitreal injection are endophthalmitis (infection inside the eye) and retinal detachment. Endophthalmitis occurs in approximately 1 out of every 1,000 injections and requires immediate treatment to save vision. Other rare complications include elevated intraocular pressure, inflammation, and cataract formation.
Off-Label Status and Cost
A defining aspect of Avastin’s use in ophthalmology is its “off-label” status. The drug was originally approved by the Food and Drug Administration (FDA) for cancer treatment, not eye disease. However, physicians can legally prescribe an FDA-approved drug off-label if they believe it benefits the patient. Clinical trials support the widespread off-label use of Avastin in the eye, demonstrating comparable efficacy and safety to approved alternatives.
This practice is driven by the cost difference. Large-dose vials of Avastin are repackaged by compounding pharmacies into smaller ophthalmic doses, making the drug substantially less expensive than competing FDA-approved treatments. This cost-effectiveness makes it a crucial option, despite the need for careful compounding to maintain sterility.
Comparative Landscape of Anti-VEGF Treatments
Avastin (bevacizumab) is one of several anti-VEGF medications used for retinal diseases, alongside Lucentis (ranibizumab) and Eylea (aflibercept), which are FDA-approved specifically for the eye. All three offer comparable visual benefits for many patients. The primary distinction between Avastin and its competitors rests on cost and regulatory status.
A single dose of Avastin is much less expensive than a dose of Lucentis or Eylea; the cost difference can be 50 times greater. For example, Eylea can cost nearly $2,000 per injection, while Avastin is often priced under $100 per dose. This difference means some insurance providers may require patients to start with Avastin before considering the more expensive, on-label options.
While all are highly effective, Eylea is sometimes favored in certain cases, such as for diabetic macular edema or to extend the time between injections. Lucentis and Eylea are manufactured as single-use ophthalmic doses. The choice of drug is often influenced by the balance between proven clinical efficacy and the financial implications of the treatment cost.