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OCT Angiography: Dye-Free Imaging of Your Retina
What Is OCT Angiography?
OCTA is a non-contact, dye-free imaging method that produces three-dimensional views of the blood vessel networks in your retina and choroid. It gives retina specialists a level of vascular detail that was not previously possible without an injection.
OCTA works by scanning the same small area of your retina multiple times in rapid succession. The tissue surrounding your blood vessels stays still, while red blood cells inside the vessels are always in motion. The device uses this difference to separate stationary tissue from flowing blood, producing what specialists call a motion-contrast image. This image is essentially a map showing where blood is actively flowing and where it is not.
The result is a three-dimensional picture of blood vessel networks at different depths within your retina and the choroid, which is the vascular layer just beneath the retina. The scan uses safe infrared light, and no injection or dye is involved at any point.
Fluorescein angiography is an older imaging test that requires a yellow-green dye to be injected into a vein in your arm. The dye travels through your bloodstream and into the blood vessels of your eye, where a special camera photographs them. While this test is effective, it carries a small risk of allergic reactions and can cause temporary nausea or skin discoloration in some patients.
OCTA provides comparable vascular detail without any dye injection. It also generates depth-resolved images, meaning it can display blood vessels at specific retinal layers separately rather than all at once. One important distinction is that OCTA cannot detect leakage from blood vessels, which fluorescein angiography can. For this reason, our retina specialists may use both tests together when a complete picture of what is happening inside the eye is needed.
One of the key strengths of OCTA is its ability to visualize blood vessels at multiple depths within the eye. Each layer provides distinct information about your retinal health that can be examined independently.
- The superficial capillary plexus (the network of small blood vessels near the inner surface of the retina)
- The deep capillary plexus (a deeper network of blood vessels within the retina)
- The choriocapillaris (the dense layer of blood vessels just beneath the retina)
- The foveal avascular zone, or FAZ (the small area at the center of the macula that normally contains no blood vessels)
Abnormalities in any of these layers can signal early signs of retinal disease, sometimes before you notice any change in your vision.
Why OCTA Matters for Your Eye Health
Many retinal diseases affect the blood vessels of the eye before causing noticeable changes in your vision. OCTA gives our team the ability to detect, measure, and track these changes with precision and without any discomfort to you as a patient.
OCTA can reveal subtle changes in blood vessel density, blood flow patterns, and the size of the foveal avascular zone that a standard eye exam may not detect. In diabetic retinopathy, for example, OCTA can identify early reductions in how well blood flows through the small vessels of the retina, often before any symptoms appear. Detecting these changes early can guide treatment decisions before significant vision loss occurs.
Because OCTA is fast and requires no dye, it can be repeated at regular intervals without added risk or significant inconvenience. Our retina specialists can compare scans from different visits to determine whether your condition is stable, improving, or progressing over time.
The scan also provides quantifiable measurements including vessel density, FAZ area, and FAZ circularity. These objective numbers give our team a reliable method for monitoring your retinal health and documenting meaningful change between visits.
OCTA findings can directly shape how we approach your care. The test can reveal areas of poor blood flow, abnormal new blood vessel growth (a process called neovascularization), and microaneurysms (tiny bulges in the walls of blood vessels). Each of these findings may suggest a different treatment direction.
When neovascularization is identified in conditions such as wet AMD or diabetic retinopathy, it may indicate the need for anti-VEGF injections. These medications block vascular endothelial growth factor (VEGF), a protein that drives the growth of abnormal blood vessels. OCTA helps our specialists identify neovascularization and monitor how well it responds to treatment over time.
Conditions We Evaluate with OCTA
OCTA is a versatile imaging tool used across a wide range of retinal conditions. It is especially valuable when detailed information about blood vessel structure and flow is essential for diagnosis or ongoing management.
In wet AMD (age-related macular degeneration), abnormal blood vessels grow beneath or within the retina in a process called macular neovascularization. OCTA can detect these abnormal vessels without any dye injection, helping to confirm the diagnosis and monitor how well treatment is working.
Anti-VEGF medications including Eylea (aflibercept), Lucentis (ranibizumab), and Vabysmo (faricimab) are used to treat wet AMD. OCTA allows our specialists to track whether these abnormal vessels are shrinking, stable, or growing after treatment begins. It is important to understand that anti-VEGF injections are used specifically for wet AMD and are not a treatment for the dry form of the disease.
Dry AMD involves different patterns of retinal change than wet AMD. In dry AMD, OCTA can reveal changes in the choriocapillaris that may indicate areas at risk for progression to geographic atrophy, an advanced stage of the disease in which retinal cells are permanently lost.
Two medications are currently approved to treat geographic atrophy: Syfovre (pegcetacoplan) and Izervay (avacincaptad pegol). Both work by slowing the progression of cell loss but do not restore vision that has already been affected. OCTA plays an important role in monitoring how the condition changes with or without treatment over time.
Diabetes can damage the small blood vessels of the retina over time in a condition called diabetic retinopathy. OCTA provides detailed maps of this damage, showing areas where vessels have been lost or where abnormal new vessels have begun to form. Our specialists use these images to determine the stage of the disease and to guide treatment planning.
Key measurements such as vessel density and foveal avascular zone size help assess the health of the retinal microcirculation, which is the network of tiny blood vessels responsible for nourishing the retina, in patients living with diabetes.
A retinal vein occlusion is a blockage in one of the veins that drains blood from the retina. It can cause swelling, bleeding, and vision loss. OCTA helps our specialists visualize the extent of vascular damage, identify areas of poor blood flow, and detect any abnormal new vessels that may have formed as a result of the blockage.
OCTA is also a valuable tool for evaluating several other conditions that affect the retinal blood vessels. Our team regularly uses it in the assessment of the following diagnoses.
- Retinal arterial occlusion (a blockage in an artery that supplies blood to the retina)
- Uveitis (inflammation inside the eye that can affect retinal blood vessels)
- Macular telangiectasia (abnormal widening of small blood vessels near the center of the retina)
What to Expect During Your OCTA Scan
The OCTA scan is straightforward and comfortable. Knowing what to expect before you arrive can help ease any anxiety about the process.
In most cases, your eyes will be dilated with eye drops before the scan. Dilation widens the pupil and allows the imaging device to capture a clearer view of your retina. The drops typically take about 15 to 30 minutes to take full effect. Afterward, your vision may be temporarily blurry and your eyes may be sensitive to light for a few hours.
No fasting is required, and you can take your regular medications as usual before your appointment. If you wear contact lenses, you may be asked to remove them before the scan. We recommend bringing a pair of sunglasses, as your eyes may remain light-sensitive for several hours after dilation.
The scan itself is quick and painless. You will sit in front of the imaging device and rest your chin on a support. A technician will ask you to focus on a small target light inside the machine. The device then scans your retina using infrared light, which you will not be able to feel at all. The entire process typically takes only a few minutes per eye.
Keeping your gaze steady on the target light is important for image quality. Movement during the scan can cause artifacts, which are minor errors in the image that reduce clarity. If needed, the technician may repeat the scan to obtain the best possible result.
There is no recovery time needed from the scan itself. If your eyes were dilated, the effects of the drops will wear off within a few hours. Our retina specialists will review your OCTA images and discuss the findings with you, often during the same visit.
Your images are stored digitally so they can be compared to scans from future visits. This allows our team to track any changes in your retinal health over time and adjust your care plan as needed.
Benefits and Limitations of OCTA
Like any diagnostic tool, OCTA has both meaningful strengths and important limitations. Understanding both helps our team use it most effectively as part of your overall retinal care.
OCTA offers several significant benefits compared to older imaging approaches. These advantages make it a first-choice imaging tool for many retinal conditions.
- No dye injection is required, eliminating the risk of allergic reactions associated with fluorescein dye
- The scan is fast, typically completed in a few minutes per eye
- Depth-resolved imaging allows separate visualization of blood vessels at specific retinal layers
- Results are available immediately and can often be reviewed during the same appointment
- The test can be repeated at regular intervals for ongoing monitoring without added risk
OCTA is a powerful tool, but it does have limitations that matter clinically. The most significant is that OCTA cannot detect leakage from blood vessels. For conditions where leakage is a critical part of the diagnosis or treatment evaluation, fluorescein angiography may still be necessary.
Image quality can also be affected by patient movement, which can introduce motion artifacts, and by media opacities such as cataracts, which can interfere with signal detection. It is also worth knowing that different OCTA devices segment and analyze retinal layers somewhat differently, which means measurements from one device may not be directly comparable to results from another.
One specific image quality issue that can affect OCTA scans is called a projection artifact. This occurs when signals from blood vessels in the superficial (inner) retinal layers appear to project onto deeper layers, making it seem as though vessels exist where they actually do not. Modern OCTA software includes correction tools designed to minimize this issue. Our retina specialists are trained to recognize and account for projection artifacts when interpreting your images.
The Evolving Science of OCTA
Research in OCTA is moving quickly, and the technology continues to expand what we can learn from retinal imaging. Our team stays current with these advances to deliver accurate, up-to-date care to every patient we see.
Four leading retina societies collaborated to create a shared framework for OCTA terminology and image interpretation. These groups include the European Society of Retina Specialists, the Japanese Retina and Vitreous Society, the American Society of Retina Specialists, and the International Retinal Imaging Society. By working together with imaging specialists, basic researchers, and biomedical engineers, they developed standards to help ensure that OCTA images are described and analyzed consistently across different clinical and research settings.
A growing body of research is exploring whether OCTA measurements could serve as indicators of cardiovascular disease. Because the blood vessels of the retina are among the smallest in the body, changes visible on OCTA may reflect broader patterns of vascular health throughout the body. Studies have reported reduced vessel density on OCTA in patients with poorly controlled high blood pressure, among other findings. This area of research is still developing, and OCTA is not currently used as a cardiovascular screening tool in routine clinical practice.
The devices used for OCTA continue to improve. Combined imaging systems that pair OCTA with standard OCT and color fundus photography are expanding the range of information available from a single scan. A new billing code specific to OCTA (CPT 92137) was established in 2025, formally recognizing it as a distinct diagnostic procedure and improving insurance coverage for many patients. These developments reflect how well-established OCTA has become as a cornerstone of modern retinal imaging.
Frequently Asked Questions
Here are answers to questions we often hear from patients who have been scheduled for an OCTA scan.
Yes. Because OCTA does not use any injected dye, it is a safe imaging option for patients with a history of dye allergies. The scan relies entirely on infrared light and does not introduce any substance into your body. If you have had a reaction to fluorescein or another contrast agent in the past, let our team know before your appointment so we can plan the most appropriate imaging approach for your evaluation.
Not necessarily. How often OCTA is performed depends on your specific diagnosis, how stable your condition is, and what information your retina specialist needs to guide your care at each stage. Some patients benefit from scanning at most visits, while others have OCTA performed at longer intervals. Your specialist will recommend the schedule that makes the most clinical sense for your individual situation.
Coverage varies depending on your insurance plan and the diagnosis being evaluated. The establishment of a dedicated billing code for OCTA in 2025 has improved coverage for many patients with qualifying retinal diagnoses. Our team can help verify your benefits before your scan and walk you through any anticipated out-of-pocket costs so there are no surprises.
In many cases, yes. OCTA can detect subtle changes in blood vessel density, blood flow patterns, and the size of the foveal avascular zone before those changes cause noticeable symptoms or appear on a routine examination. This is particularly relevant for patients with diabetes, high blood pressure, a family history of macular degeneration, or other known risk factors for retinal disease. Identifying these early changes gives our team the opportunity to act sooner, which can make a meaningful difference in long-term outcomes.
Certain vision symptoms require immediate evaluation and should not wait for a scheduled appointment. These include a sudden increase in floaters, new flashes of light in your vision, a dark curtain or shadow spreading across your visual field, or sudden vision loss in one eye. If you experience any of these symptoms, contact our office right away or go to the nearest emergency room. OCTA and other imaging tools can help evaluate what is happening inside your eye, but the most important step is being seen as quickly as possible.
OCTA can identify early structural changes in the retinal and choroidal blood vessels that are associated with macular degeneration, including areas of reduced blood flow in the choriocapillaris that may indicate an increased risk of disease progression. However, a formal AMD diagnosis is based on a combination of imaging findings, clinical examination, and your full medical history considered together. Regular OCTA monitoring is most valuable as part of a comprehensive retinal care plan rather than as a standalone screening test.
Personalized Retinal Care at New England Retina Associates
At New England Retina Associates, our fellowship-trained retina specialists use OCT angiography as part of a thorough, individualized approach to diagnosing and managing retinal disease for patients throughout Connecticut. We are committed to combining advanced diagnostic technology with expert, compassionate care at every visit. Whether you have been referred by another provider or are seeking an evaluation on your own, we welcome you to our practice. Contact us to schedule an appointment at the location most convenient for you.
30 Years of Care & Commitment
