Vascular Endothelial Growth Factor (VEGF) is a protein naturally produced by the body, playing a role in the formation of new blood vessels. While beneficial for normal physiological processes like wound healing, an excess of VEGF can lead to the uncontrolled growth of fragile, leaky blood vessels, particularly in the eye. Anti-VEGF injections are a medical treatment designed to manage specific eye conditions by targeting and neutralizing this protein. These injections represent a significant advancement in ophthalmology, helping to preserve vision in individuals affected by certain retinal diseases.
Understanding VEGF and Its Role
VEGF, or Vascular Endothelial Growth Factor, is a protein that plays a role in the formation of new blood vessels. In a healthy body, VEGF helps in processes such as wound healing, where new blood vessels are needed to repair damaged tissue and restore blood flow. It also supports the maintenance and function of the vascular, glial, neuronal, and epithelial components of the adult retina.
However, when VEGF activity becomes excessive, it can cause problems in the eye. Overproduction of VEGF in the eye can trigger the growth of abnormal and fragile blood vessels beneath or within the retina. These new vessels are prone to leaking fluid and blood, leading to swelling, bleeding, and scarring that can damage the light-sensitive cells responsible for vision.
Conditions Treated by Anti-VEGF Injections
Anti-VEGF injections treat several eye conditions characterized by abnormal blood vessel growth and leakage.
Age-related Macular Degeneration (AMD)
Wet AMD is a primary indication. In this form, abnormal blood vessels grow under the macula, the central part of the retina responsible for sharp, detailed vision. This growth causes fluid leakage and rapid central vision loss.
Diabetic Retinopathy (DR) and Diabetic Macular Edema (DME)
In individuals with long-standing diabetes, elevated blood sugar levels can lead to increased VEGF production. This causes damage to retinal blood vessels, resulting in swelling (macular edema) and the growth of new, fragile blood vessels that can bleed into the eye, leading to vision impairment.
Retinal Vein Occlusion (RVO)
When a retinal vein becomes blocked, it leads to increased pressure in the capillaries, causing hemorrhages and fluid leakage within the retina. This can result in a lack of oxygen, which in turn triggers the release of VEGF, exacerbating fluid buildup and blurred vision.
How Anti-VEGF Injections Work
Anti-VEGF medications work by binding to and neutralizing the Vascular Endothelial Growth Factor protein in the eye. This prevents VEGF from attaching to its receptors on endothelial cells. By blocking this interaction, the medications inhibit the growth of new, abnormal blood vessels and reduce fluid leakage. This helps resolve swelling and prevent further retinal damage.
Several anti-VEGF medications are commonly used, including ranibizumab (Lucentis), aflibercept (Eylea), brolucizumab (Beovu), and faricimab (Vabysmo). Bevacizumab (Avastin) is also widely used “off-label” for eye conditions. While these drugs all target VEGF, some, like aflibercept, can also bind to other growth factors like placental growth factor (PlGF), potentially offering additional benefits. Faricimab is a bispecific antibody that targets both VEGF-A and angiopoietin-2, which may allow for longer intervals between injections for some patients.
The Anti-VEGF Injection Experience
Receiving an anti-VEGF injection is an outpatient procedure performed in an ophthalmologist’s office. Before the injection, the eye is prepared with numbing eye drops or gel and an antiseptic solution, often iodine, to prevent infection. An eyelid speculum may be used to keep the eye open during the procedure.
The injection is quick, usually taking only a few seconds, and is administered into the vitreous, the jelly-like substance in the center of the eye. Most patients report slight pressure but little to no pain during the injection. After the procedure, the eye is often cleaned with saline.
Following the injection, mild and temporary side effects are common, such as a gritty sensation, slight soreness, redness at the injection site, or temporary floaters. These symptoms resolve within a day or two. Patients are advised to avoid rubbing their eye, swimming, or wearing contact lenses for a few days to reduce infection risk. While rare, more serious complications can occur, including infection (endophthalmitis) or retinal detachment, with an estimated risk of about 1 in 1,000 to 1 in 3,000 injections. These require immediate medical attention.