Choroidal Neovascularization: Causes, Symptoms, and Treatment
What Is Choroidal Neovascularization?
CNV involves the growth of new, fragile blood vessels from the choroid, the layer of blood vessels that sits beneath the retina. These abnormal vessels push through a thin barrier called Bruch membrane and extend into the space beneath the retinal pigment epithelium (RPE), the layer of cells that supports the retina. Because these vessels are weak and poorly formed, they tend to leak fluid and blood, which leads to swelling, scarring, and vision loss.
When abnormal vessels grow beneath the macula, the condition is also referred to as macular neovascularization. The macula is the central part of the retina responsible for sharp, detailed vision used in reading, driving, and recognizing faces. Fluid and blood leaking from these vessels damage the delicate photoreceptor cells in the macula, resulting in distorted or lost central vision.
A protein called vascular endothelial growth factor (VEGF) plays a central role in CNV. VEGF normally helps maintain the choroidal blood supply, but conditions such as low oxygen levels or tissue damage can trigger excessive VEGF production. When this process becomes uncontrolled, abnormal vessels break through Bruch membrane and begin leaking into the macula. Blocking VEGF is the foundation of modern CNV treatment.
Age-related macular degeneration (AMD) is the most common condition linked to CNV. When CNV develops as part of AMD, it is classified as wet or neovascular AMD. However, CNV can develop from several other causes as well.
- Pathologic myopia, a severe form of nearsightedness that causes structural changes to the eye
- Inflammatory conditions such as uveitis, which involves swelling inside the eye
- Central serous chorioretinopathy, a condition in which fluid builds up beneath the retina
- Choroidal nevi, which are benign growths beneath the retina that can occasionally trigger vessel growth
The treatment approach for CNV is similar across these conditions, though the underlying cause may influence how the condition is monitored over time.
Who Is at Risk
CNV can affect people of different ages, though certain groups carry a higher risk. Knowing your risk factors helps ensure that early changes are caught and treated before significant vision loss occurs.
CNV most commonly affects older adults when it develops as part of wet AMD. Advanced age is one of the strongest risk factors. Cigarette smoking significantly increases the likelihood of developing CNV. Certain genetic variations involving the immune system's inflammatory response also increase risk, particularly for AMD-related CNV.
Pathologic myopia is the most common cause of CNV in adults under the age of 50. High myopia is defined by a significantly elongated eye or a refractive error greater than negative 6 diopters. A meaningful percentage of people with pathologic myopia go on to develop myopic CNV, and because this form of CNV can develop without warning, regular monitoring is especially important for this group.
Central serous chorioretinopathy can lead to CNV in a subset of cases. Choroidal nevi located near the macula or optic disc may also be associated with CNV, particularly when features such as increased thickness, subretinal fluid, orange pigment, or symptoms like flashes of light or floaters are present. A retina specialist can evaluate these risk features during a dilated eye exam.
Signs and Symptoms of CNV
CNV symptoms often appear suddenly and can worsen quickly without treatment. Recognizing the warning signs early and seeking prompt evaluation is one of the most important steps you can take to preserve your vision.
The most common early symptom of active CNV is a change in the clarity or shape of central vision. Many people notice that straight lines appear wavy or bent, a distortion called metamorphopsia. Others experience a blurry or blank spot in the center of their visual field, known as a central scotoma. These changes often come on suddenly and may affect one eye before the other.
Certain symptoms require immediate evaluation by a retina specialist. Do not wait for a routine appointment if you experience any of the following.
- Sudden blurring or distortion of central vision
- A dark, gray, or blank spot in the center of your visual field
- Straight lines that appear wavy or crooked when they previously looked straight
- Difficulty distinguishing colors, particularly in one eye
- A sudden worsening of vision that had been stable
Any of these symptoms may indicate active CNV that requires prompt treatment to prevent further damage.
An Amsler grid is a simple printed chart with a grid pattern and a dot at the center. To use it, cover one eye, hold the grid at reading distance, and focus on the center dot. If any lines appear wavy, blurry, or missing, contact a retina specialist right away. Home monitoring with an Amsler grid is a helpful tool for catching changes early, but it is not a substitute for regular professional examinations.
How CNV Is Diagnosed
Accurate diagnosis of CNV requires specialized imaging performed by a retina specialist. The combination of a dilated examination and advanced imaging tests allows for precise evaluation of the location, size, and activity of abnormal blood vessels.
A retina specialist begins with a dilated eye exam, during which special drops are used to widen the pupil. This allows a detailed view of the retina and macula. Active CNV may appear as a small, slightly elevated, grayish lesion beneath the macula. The specialist will also look for associated fluid, blood, or scarring.
Optical coherence tomography (OCT) is a noninvasive imaging test that produces detailed cross-sectional images of the retina. OCT can reveal fluid beneath or within the retina, thickening of the macula, and abnormal tissue associated with CNV. This test is essential for both confirming the diagnosis and tracking the response to treatment over time.
Fluorescein angiography involves injecting a yellow dye into a vein in the arm. As the dye travels through the blood vessels of the retina, a series of photographs are taken. This test highlights areas where vessels are leaking and helps the retina specialist determine the exact location, size, and type of CNV. It remains one of the most important tools for evaluating neovascularization.
Indocyanine green (ICG) angiography uses a different dye that provides better visualization of the deeper choroidal blood vessels. This test is particularly useful when the full extent or type of CNV is not completely clear from other imaging. It is often performed alongside fluorescein angiography for a more thorough evaluation.
Treatment Options for CNV
Treatment for CNV has advanced significantly. Anti-VEGF therapy is the current standard of care, and it has transformed outcomes for many patients who previously faced progressive vision loss. Your retina specialist will recommend a treatment plan based on the type and activity of your CNV.
Anti-VEGF medications work by blocking the protein that drives abnormal blood vessel growth. These medications are injected directly into the vitreous, the gel-like substance inside the eye, in a procedure performed in the retina specialist's office. The eye is numbed with anesthetic drops beforehand, and the injection itself takes only a few seconds. Most patients report mild pressure or temporary floaters, which typically resolve quickly.
Several anti-VEGF medications are available, and each differs in structure, dosing interval, and approved indications. Your retina specialist will select the most appropriate option for your situation.
- Ranibizumab (Lucentis) was among the first anti-VEGF therapies approved for both AMD-related and myopic CNV and is typically given every four weeks
- Aflibercept (Eylea) is one of the most widely used agents and is typically given every four to eight weeks after an initial monthly loading phase
- High-dose aflibercept (Eylea HD) may allow extended dosing intervals of every eight to sixteen weeks after the loading phase
- Faricimab (Vabysmo) is a bispecific antibody that blocks both VEGF-A and angiopoietin-2, with dosing possible every four to sixteen weeks after loading
- Bevacizumab (Avastin) is used off-label for CNV and has been shown in studies to be effective for treating this condition
FDA-approved biosimilars for ranibizumab are also available and offer additional treatment options that may help improve access to anti-VEGF therapy.
Photodynamic therapy (PDT) uses a light-activated drug called verteporfin, which is injected into a vein in the arm. A specialized laser is then directed at the abnormal vessels, activating the drug and helping to seal the leakage. While anti-VEGF therapy has become the primary treatment for most cases of CNV, PDT may still be used in certain clinical situations, sometimes in combination with anti-VEGF injections.
Treatment typically begins with a series of three monthly loading injections. After this loading phase, the retina specialist determines the appropriate interval between treatments based on how the eye responds. OCT imaging is used at each follow-up visit to check for fluid and assess the health of the macula.
Some patients need injections every four to eight weeks on an ongoing basis, while others may be able to extend the time between treatments. The schedule is always individualized. It is important to keep all scheduled appointments, as missing or delaying injections can allow CNV to become active again.
What to Expect From Treatment
Having realistic expectations about treatment helps patients stay engaged with their care over the long term. Anti-VEGF therapy can produce meaningful benefits, but CNV is often a chronic condition that requires continued management.
Anti-VEGF therapy can stabilize vision in most patients and improve vision in a meaningful number of cases. Outcomes vary depending on the size and location of the CNV, how long it has been present, and how quickly treatment begins. Early treatment generally leads to better results. Not all lost vision can be recovered, and ongoing treatment is often necessary to maintain the benefits that have been achieved.
CNV is a chronic condition for most patients, and staying active in your care makes a real difference. Using an Amsler grid at home, keeping all follow-up appointments, and reporting any sudden changes in vision right away are among the most effective things you can do between visits. Quitting smoking, eating a diet rich in leafy green vegetables and fish, and wearing sunglasses with UV protection can also support overall retinal health.
For individuals who have experienced significant vision loss from CNV, low vision rehabilitation can help maximize remaining sight. Low vision specialists provide tools such as magnifying devices, specialized lighting, and adaptive technologies that make daily tasks more manageable. Your retina specialist can refer you to low vision services if needed.
Frequently Asked Questions
These answers address common questions patients have after learning about their diagnosis or starting treatment for CNV.
CNV is the process that defines wet AMD, but the two terms are not interchangeable. Wet AMD is a specific diagnosis in which CNV develops as a complication of age-related macular degeneration. CNV can also develop from other causes, including pathologic myopia and inflammatory eye diseases. If you have been told you have wet AMD, CNV is the active component that requires treatment. If you have CNV from a different cause, the treatment approach is often similar, but your overall management plan may differ.
Active CNV typically shows fluid on OCT imaging and may be associated with new or worsening symptoms. Inactive CNV has stopped leaking and shows no fluid. Your retina specialist assesses activity at each visit using OCT and, when needed, angiography. Even when CNV appears inactive, it can reactivate, which is why regular monitoring continues even after symptoms have resolved.
Missing or delaying an injection allows VEGF levels in the eye to rise again, which can trigger renewed vessel growth and leakage. This can lead to fluid returning to the macula and a decline in vision. If you need to reschedule, contact our office as soon as possible so that the gap in treatment is minimized. Do not wait until your next originally scheduled appointment if you notice any change in your vision in the meantime.
Intravitreal anti-VEGF injections are generally safe and well tolerated. Common temporary side effects include mild redness, a gritty sensation, and brief floaters. Serious complications such as infection inside the eye, known as endophthalmitis, are rare but possible. Our retina specialists use careful antiseptic techniques to minimize this risk. If you experience significant pain, increasing redness, or a sudden drop in vision after an injection, contact us right away rather than waiting for your next scheduled visit.
While there is no certain way to prevent CNV, several steps can meaningfully reduce your risk. Not smoking is one of the most impactful choices, as smoking is strongly associated with both AMD and CNV. A healthy diet, cardiovascular health management, and UV eye protection may also offer some protective benefit. For people with high myopia or dry AMD, regular dilated eye exams are essential for catching early signs before significant vision loss develops. Speak with your retina specialist about a monitoring schedule that fits your specific risk level.
FDA-approved biosimilars are required to demonstrate that they are highly similar to the reference medication in terms of safety and effectiveness. For approved indications such as neovascular AMD and myopic CNV, biosimilars offer a comparable option to the original product. Your retina specialist will consider your individual clinical situation, insurance coverage, and other factors when deciding which medication is most appropriate for your care.
Schedule a Retina Evaluation at Rhode Island Eye Institute
Our fellowship-trained retina specialists, Dr. Gaurav Gupta and Dr. Pranjal Thakuria, provide expert diagnosis and treatment for choroidal neovascularization and a full range of retinal conditions. With multiple locations and advanced diagnostic technology, Rhode Island Eye Institute is equipped to provide the specialized care your vision deserves. If you are experiencing changes in your central vision, or if you have a condition that puts you at risk for CNV, we encourage you to schedule a comprehensive evaluation with our team.