Retinal Imaging in Diabetic Eye Exams
Understanding Retinal Imaging for Diabetes
Diabetic retinopathy can progress silently for years. By the time you notice blurred vision or dark spots, substantial damage may have already occurred. Retinal imaging allows a retina specialist to see the tiny blood vessels and layers of the retina in great detail. This means problems can be found and treated before significant vision loss happens.
Early diagnosis and treatment are critical. With timely care, vision loss from diabetic retinopathy can be greatly reduced. Retinal imaging makes earlier detection possible by revealing changes that are too subtle to see during a standard eye exam alone.
A dilated fundus examination, where drops widen the pupil so a specialist can look inside the eye, remains the gold standard for screening (AAO, Preferred Practice Pattern). Retinal imaging adds another layer of precision. High-resolution photographs and scans capture detailed records of the retina. These records can be compared over time to track any changes.
Some imaging methods can also detect abnormalities in the peripheral retina. These are areas that are difficult to examine with traditional tools. Research using ultra-widefield imaging has shown that diabetic retinal lesions appear in the peripheral retina in up to 40% of eyes (DRCR Retina Network). In 10% of eyes, those peripheral lesions indicated a more severe grade of disease than the central exam alone would suggest.
Several imaging technologies are commonly used to evaluate and monitor diabetic retinopathy. Each provides different information about the health of your retina.
- Optical coherence tomography (OCT): Creates detailed cross-sectional images of the retina to measure its thickness and detect fluid leakage.
- OCT angiography (OCTA): A noninvasive scan that produces three-dimensional images of retinal blood vessels without requiring dye injection.
- Fundus photography: Captures color photographs of the retina to document and monitor disease progression over time.
- Fluorescein angiography (FA): Uses a yellow dye injected into a vein in the arm to highlight blood vessel circulation and identify leaking or blocked vessels.
- Ultra-widefield (UWF) imaging: Photographs a wide area of the retina in a single image, covering far more than standard cameras can capture.
How Each Imaging Technology Works
OCT uses waves of light to capture individual cross-sectional images of the retina. These images are assembled into a three-dimensional view. A retina specialist can then examine each layer of retinal tissue in fine detail. OCT can measure retinal thickness, which is important because swelling from fluid leakage is a key sign of diabetic macular edema.
The scan is quick and painless. You simply rest your chin on a support and look at a target light while the machine captures images. No dye injection is needed, and the entire process typically takes only a few minutes.
OCT angiography is a newer, noninvasive technique that generates high-resolution images of the retinal blood vessels at distinct depths. It works by detecting the motion of circulating blood cells. This produces detailed three-dimensional maps of the tiny capillaries (the smallest blood vessels) in the retina and the tissue layer beneath it called the choriocapillaris.
OCTA surpasses traditional fluorescein angiography in some ways. It does not require a dye injection, is safer, and provides better resolution of fine capillary networks. Its depth-resolved capability means it can show blood flow in individual retinal layers. OCTA is increasingly used in managing diabetic retinopathy and can detect early vascular abnormalities in people with prediabetes.
Fundus photography creates detailed color photographs of the inside of the eye. These photographs serve as a lasting record that can be compared at future visits to see if the disease is stable or progressing. There is level I evidence that single-field fundus photography with interpretation by trained readers can serve as an effective screening tool (AAO, Preferred Practice Pattern).
During the procedure, a camera takes photographs of your retina through your dilated pupil. The bright flash may be briefly uncomfortable but causes no harm. Some newer systems can photograph the retina through an undilated pupil, making the process faster and more convenient.
Fluorescein angiography provides a dynamic look at blood vessel circulation in the retina. A yellow dye called fluorescein is injected into a vein in your arm. As the dye travels through the blood vessels of the eye, a special camera takes rapid photographs. Areas where blood vessels leak, are blocked, or have abnormal growth appear clearly on the images.
This test is very useful for planning treatment in more advanced stages of diabetic retinopathy. It is generally safe, though some people may feel mildly nauseous from the dye. Skin and urine may temporarily turn yellow. Serious allergic reactions are rare.
Traditional retinal photographs cover a limited area of the retinal surface (AAO, 2023). Ultra-widefield imaging devices can capture up to 200 degrees of the retina in a single image taken in about 0.25 seconds (Optos, manufacturer data). This wider view is especially valuable for diabetic eye exams because it reveals disease in the peripheral retina that might otherwise go undetected.
Ultra-widefield imaging can be combined with OCT angiography. Ultra-widefield OCTA is reaching accuracy similar to fluorescein angiography for detecting abnormal new blood vessel growth. It also allows better characterization of microvascular changes in the peripheral retina.
Who Should Have Retinal Imaging
Anyone who has diabetes is at risk of developing diabetic retinopathy. This includes people with type 1, type 2, and gestational diabetes. Several factors increase the risk further.
- Longer duration of diabetes: People who have had diabetes for 15 years or more are at significantly higher risk of developing diabetic retinopathy (PMC, 2023).
- Higher fasting blood sugar levels.
- Use of diabetic oral medications or insulin, which may reflect more advanced diabetes.
- Greater waist-to-hip ratio.
Diabetic retinopathy affects men and women about equally. In 2010, Hispanic Americans age 50 and older had the highest rates of diabetic retinopathy at about 8%, compared with about 5% in Black and white Americans (NEI, 2010). Hispanic Americans accounted for 16% of all cases and Black Americans accounted for 11% (NEI, 2010).
Because diabetic retinopathy can develop without symptoms, screening recommendations apply to all people with diabetes regardless of whether they notice vision changes.
National guidelines recommend that people with type 1 diabetes have a comprehensive dilated eye exam within five years of diagnosis. People with type 2 diabetes should be examined at the time of diagnosis. After the initial exam, annual or more frequent screenings may be recommended based on the severity of any findings.
A retina specialist may recommend more frequent imaging if there are signs of progression. People with gestational diabetes should also have an eye exam during pregnancy.
Artificial Intelligence in Diabetic Retinal Screening
Artificial intelligence systems are now available to help screen for diabetic retinopathy. These systems capture digital photographs of the retina, often through an undilated pupil, and upload them to cloud-based software. The software generates an automated assessment indicating whether diabetic retinopathy is present.
Three autonomous AI systems have received approval from the U.S. Food and Drug Administration (FDA) for the detection of diabetic retinopathy. IDx-DR, approved in 2018, was the first medical device to use artificial intelligence for this purpose. It uses deep learning algorithms to analyze fundus images. EyeArt, developed by Eyenuk, later received FDA clearance as well.
In a study of 942 individuals with diabetes, the EyeArt autonomous AI system showed 96% sensitivity and 88% specificity for detecting more-than-mild diabetic retinopathy (AAO, EyeNet). For vision-threatening diabetic retinopathy, sensitivity was the vast majority and specificity was the vast majority (AAO, EyeNet). Sensitivity refers to correctly identifying people who have the disease. Specificity refers to correctly identifying people who do not.
These results suggest that AI screening can be a highly effective tool for identifying patients who need referral to a retina specialist for further evaluation and treatment.
AI screening systems are being used in primary care offices, endocrinology clinics, and community health settings. Because these devices can sometimes capture images through undilated pupils, screening becomes more accessible. Some newer handheld devices, including smartphone attachments, allow retinal images to be captured and transmitted to an eye care professional for review.
It is important to understand that AI screening is a detection tool. A positive result means you should see a retina specialist for a complete evaluation. AI screening does not replace a comprehensive dilated eye exam.
What to Expect During Retinal Imaging
For many retinal imaging tests, your eyes will be dilated with special drops. These drops take about 15 to 30 minutes to work. Once dilated, your eyes will be sensitive to bright light and your near vision may be blurry for several hours. Bringing sunglasses and arranging a ride home is a good idea.
Some newer imaging systems, particularly those used for AI-based screening or ultra-widefield photography, can take images through undilated pupils. Your retina specialist or referring doctor will let you know if dilation is needed.
Most retinal imaging is comfortable and straightforward. For OCT and OCTA scans, you rest your chin on a support and look at a small light while the machine captures images. The process takes only a few minutes per eye. For fundus photography, a camera takes a series of photographs. You may see a bright flash with each photo.
For fluorescein angiography, a small needle is used to inject dye into a vein in your arm. The injection feels like a standard blood draw. As the dye travels to your eye, rapid photographs are taken over several minutes. You may notice a warm sensation or mild nausea from the dye. Your skin and urine may appear yellow for up to 24 hours afterward.
Results from retinal imaging are often available the same day. Your retina specialist will review the images and discuss findings with you. If diabetic retinopathy is detected, a treatment plan will be discussed based on the severity of the disease.
Images are stored digitally so they can be compared at future visits. This comparison over time is one of the most valuable aspects of retinal imaging. It allows your retina specialist to detect subtle changes that might be missed in a single examination.
Living with Diabetes and Protecting Your Vision
Because diabetic retinopathy often causes no symptoms in its early stages, regular screening is the most effective way to protect your vision. Many people with diabetes do not realize they have retinopathy until it has progressed. Routine retinal imaging catches changes early, when treatment is most effective.
Studies have shown that photography can be more sensitive in identifying sight-threatening retinopathy than clinical examination with ophthalmoscopy alone (AAO, Preferred Practice Pattern). Adding advanced imaging to your regular diabetic eye exam provides a more complete picture of your retinal health.
Controlling blood sugar, blood pressure, and cholesterol can slow the progression of diabetic retinopathy. Work closely with your primary care doctor or endocrinologist to maintain healthy levels. Following your treatment plan for diabetes is one of the most important steps you can take to preserve your vision.
If you smoke, quitting can also reduce your risk of progression. A healthy diet, regular physical activity, and weight management support both your overall health and your eye health.
If you experience any of the following symptoms, see a retina specialist or go to the emergency room immediately. These may indicate a serious problem that needs urgent treatment.
- Sudden increase in floaters (spots or strings drifting across your vision).
- Flashes of light in your vision.
- A curtain or shadow appearing over part of your visual field.
- Sudden vision loss in one eye.
- Blurred vision that worsens rapidly.
When to See a Retina Specialist
If a screening exam, AI system, or primary care doctor identifies signs of diabetic retinopathy, you should be referred to a retina specialist for a comprehensive evaluation. A retina specialist is a vitreoretinal surgeon with advanced training in diagnosing and treating diseases of the retina.
Do not delay this referral. Early evaluation and, if needed, early treatment can greatly reduce the risk of vision loss.
Even if your initial screening shows no signs of diabetic retinopathy, continued monitoring is essential. The disease can develop at any time as long as you have diabetes. Your retina specialist will recommend a follow-up schedule based on your individual risk factors and any findings from previous exams.
Retinal imaging makes ongoing monitoring more precise. By comparing images over months and years, a retina specialist can detect the earliest changes in your retinal blood vessels and act before those changes threaten your sight.
Questions and Answers
Retinal imaging is not painful. OCT, OCTA, fundus photography, and ultra-widefield imaging involve no contact with the eye. For fluorescein angiography, the injection of dye into a vein in the arm may cause brief discomfort similar to a blood draw. Some people experience mild nausea from the dye, but this usually passes quickly.
Yes. One of the greatest advantages of retinal imaging is its ability to detect diabetic retinopathy at very early stages, often before any symptoms are present. OCTA can even identify early vascular abnormalities in people with prediabetes. This early detection is critical because treatment is most effective when started before significant damage has occurred.
The recommended frequency depends on your type of diabetes, how long you have had it, and whether any retinopathy has been found. Most guidelines recommend at least an annual comprehensive dilated eye exam for people with diabetes. Your retina specialist may recommend imaging more frequently if there are signs of disease. Follow the schedule your retina specialist provides.
No. AI screening is a valuable tool for detecting diabetic retinopathy in settings like primary care offices. It can identify people who need further evaluation. However, a positive AI screening result should be followed by a comprehensive exam with a retina specialist. AI cannot replace the full clinical assessment, advanced imaging, and treatment planning that a retina specialist provides.
If retinal imaging reveals diabetic retinopathy, your retina specialist will discuss the severity and recommend a treatment plan. In early stages, careful monitoring and blood sugar management may be sufficient. More advanced stages may require intravitreal injections (injections of medication into the eye), laser treatment, or surgery. The goal of treatment is to slow or stop progression and preserve as much vision as possible.