Diabetic retinopathy – Diagnostics – Overview of Information and Clinical Research

Early detection can save your sight. Diabetic retinopathy often develops silently, with no warning signs in its initial stages, making regular screening essential for anyone living with diabetes. Understanding when and how to get tested can make the difference between preserving clear vision and facing permanent vision loss.

Introduction: Who Should Be Tested and When

If you have diabetes, regular eye examinations are not optional—they are a crucial part of managing your health. Diabetic retinopathy is a complication that affects the blood vessels in the retina, which is the light-sensitive tissue at the back of your eye that allows you to see. The condition can develop in anyone with type 1 diabetes, type 2 diabetes, or even gestational diabetes, which is diabetes that occurs during pregnancy.^[1]

The challenge with diabetic retinopathy is that it usually does not cause any symptoms during its early stages. You may not notice any changes in your vision until the damage becomes more severe or widespread throughout your retina. This is why waiting for symptoms to appear before seeking care can be dangerous. By the time vision problems become noticeable, the disease may already be at an advanced stage where treatment options are more limited and the damage may be irreversible.^[2]

Anyone with diabetes should undergo comprehensive eye screening. If you are 12 years or older and have diabetes, you should be invited for diabetic eye screening every one to two years. This regular monitoring helps catch any changes early, when interventions are most effective. Even if your vision seems perfectly fine, these screenings are essential because they can detect problems before you become aware of them.^[5]

You should also schedule regular eye tests at an optician’s office to check for other eye problems linked to diabetes, such as cataracts and glaucoma. Having diabetes makes you two to five times more likely to develop cataracts and nearly doubles your risk of developing a type of glaucoma called open-angle glaucoma. These conditions can develop alongside diabetic retinopathy or independently, so comprehensive eye care is important.^[2]

⚠️ Important

If you experience sudden changes in your vision—such as sudden blurriness, dark floating spots, or difficulty seeing—contact a medical professional right away. Do not wait for your scheduled screening appointment. These symptoms could indicate that blood vessels in your retina have started bleeding or that other serious complications have developed.^[1]

Women with diabetes who become pregnant, or women who develop gestational diabetes during pregnancy, face an increased risk of diabetic retinopathy. If you are pregnant and have diabetes, your healthcare professional might recommend additional eye examinations throughout your pregnancy to monitor any changes that could affect your vision.^[1]

Your risk of developing diabetic retinopathy increases the longer you have diabetes and if your blood sugar levels are not managed well. Over time, more than half of people with diabetes will develop some form of diabetic retinopathy. However, controlling your diabetes through healthy lifestyle choices, medication adherence, and regular monitoring can significantly lower your risk and slow down the progression of the disease if it does develop.^[2]

Diagnostic Methods for Identifying Diabetic Retinopathy

The primary way to diagnose diabetic retinopathy is through a dilated eye exam. This examination is considered the gold standard for detecting diabetic eye disease. During this exam, an eye care professional places special drops in your eyes. These drops widen your pupils, which are the black circles in the center of your eyes. Widening the pupils allows the eye care professional to get a much better view of the inside of your eye, especially the retinal tissue at the back.^[9]

The drops used to dilate your pupils can cause your near vision—the vision you use for reading—to blur for several hours after the examination. This is a normal temporary effect, and you should plan accordingly. You may want to bring someone with you to drive you home, or avoid scheduling important tasks that require clear close-up vision immediately after your appointment.

During the dilated eye exam, the physician looks for several specific signs of diabetic retinopathy. They check for swelling in the retina that threatens vision, a condition called diabetic macular edema. The macula is the central part of the retina that provides the sharp, detailed vision needed for reading and recognizing faces. When fluid leaks into this area, it causes swelling and can blur your vision.^[6]

The eye care professional also looks for evidence of poor blood vessel circulation in the retina, which is called retinal ischemia. This occurs when damaged blood vessels fail to supply adequate blood flow to parts of the retina. They will also check for abnormal blood vessels that may predict an increased risk of developing new, fragile blood vessels, as well as any new blood vessels or scar tissue already forming on the surface of the retina. This advanced stage is known as proliferative diabetic retinopathy.^[6]

In many screening programs, diabetic eye screening involves taking photographs of the back of your eye. These photographs can be reviewed by trained specialists to look for signs of diabetic retinopathy. This approach makes screening more accessible and efficient, allowing more people to be checked regularly.^[5]

Another important diagnostic test is optical coherence tomography, commonly called OCT. This test provides highly detailed cross-sectional images of the retina. Think of it like taking a slice through a layer cake to see all the different layers. OCT images show the thickness of the retina and help determine whether fluid has leaked into retinal tissue. The test is non-invasive and painless. Later, OCT exams can be repeated to check whether treatment is working and if the swelling is improving.^[6]

A fluorescein angiography test may be performed in some cases. After your eyes are dilated, a special dye called fluorescein is injected into a vein in your arm. As the dye circulates through the blood vessels in your body, it eventually reaches the blood vessels in your eyes. A special camera takes a series of pictures as the dye flows through these vessels. The pictures can pinpoint exactly which blood vessels are closed, broken, or leaking. This detailed information helps doctors understand the extent of damage and plan appropriate treatment.^[9]

In addition to these specialized eye tests, a comprehensive dilated eye exam evaluates many other aspects of your eye health. The examination checks your need for corrective lenses, measures eye pressure to look for glaucoma, examines the front of the eye including the eyelids and cornea, checks for dry eye and cataracts in the lens, and provides a complete examination of the retina and vitreous, which is the gel-like substance filling the inside of your eye.^[6]

⚠️ Important

Regular dilated eye exams by an ophthalmologist are especially important for those at higher risk for diabetic retinopathy or diabetes. If you are over 50, an exam every year is recommended so the eye physician can look for signs of diabetes or diabetic retinopathy before any vision loss has occurred. Early detection truly makes a difference in preserving your sight.^[6]

The examination also helps distinguish diabetic retinopathy from other conditions that can affect vision. Many eye problems can cause similar symptoms, such as blurred vision or floaters. A thorough diagnostic evaluation ensures that the correct condition is identified so that appropriate treatment can be provided.

Diabetic retinopathy develops in stages, and diagnostic testing helps determine which stage you are in. There are two main stages: nonproliferative diabetic retinopathy, which is the earlier stage, and proliferative diabetic retinopathy, which is more advanced. In nonproliferative retinopathy, blood vessels in the retina leak fluid. The damage eventually makes some vessels close off as your body tries to repair them. In proliferative retinopathy, new blood vessels start to form to increase blood flow to areas not getting enough blood. However, these new vessels are fragile and can leak blood and fluid into the vitreous, leading to more serious vision problems.^[3]

There is also a type of diabetic retinopathy called diabetic maculopathy. In its early stages, it has no symptoms and does not affect vision. However, in a small number of people, it progresses to an advanced stage and affects the central part of vision. This means you may be able to see around the edges of your vision but not be able to read clearly because the central, detailed vision is affected.^[5]

Diagnostics for Clinical Trial Qualification

When patients are being considered for enrollment in clinical trials studying new treatments for diabetic retinopathy, specific diagnostic tests and criteria are used to determine eligibility. These tests help ensure that the right patients are selected for each study and that the results can be properly measured and compared.

Clinical trials typically require a comprehensive dilated eye exam as a baseline assessment. This establishes the starting point of the disease and documents exactly what damage exists before any experimental treatment begins. The dilated exam identifies the stage of diabetic retinopathy and whether complications like diabetic macular edema are present.

Optical coherence tomography is commonly used as a standard measurement tool in clinical trials. Because OCT provides precise, quantifiable measurements of retinal thickness and can detect even small amounts of fluid accumulation, it serves as an objective way to track whether an experimental treatment is working. Researchers can compare OCT images taken before treatment, during treatment, and after treatment to see if the retina’s condition is improving, staying stable, or worsening.

Fluorescein angiography may also be required for trial enrollment. This test provides detailed information about blood vessel damage and leakage that helps researchers categorize the severity of disease. It can also help identify which patients are most likely to benefit from a particular type of experimental treatment.

Clinical trials often have specific inclusion and exclusion criteria based on diagnostic findings. For example, a trial might only accept patients with proliferative diabetic retinopathy but exclude those who have already had certain types of treatment. Or a trial studying treatments for diabetic macular edema might require that patients have a certain level of retinal swelling as measured by OCT. These criteria ensure that the study population is appropriate for the treatment being tested.

Blood tests to measure blood sugar control, such as hemoglobin A1C levels, are typically required for clinical trial participation. These tests help researchers understand how well a patient’s diabetes is being managed overall. Blood pressure measurements and cholesterol levels may also be documented, as these factors can affect diabetic retinopathy progression and treatment outcomes.

Visual acuity testing, which measures how clearly you can see, is another standard component of clinical trial screening and monitoring. This involves reading letters or numbers on an eye chart at a specific distance. Your visual acuity score provides an objective measure of your vision function that can be tracked throughout the trial to determine if treatment is preserving or improving your sight.

Some clinical trials may use additional specialized imaging techniques or newer diagnostic technologies that are being evaluated alongside the experimental treatment. These might include different types of retinal imaging or biomarker testing to better understand how the disease is progressing or responding to treatment at a molecular level.

Prognosis and Survival Rate

Prognosis

The outlook for people with diabetic retinopathy depends greatly on several factors, including how long someone has had diabetes, how well blood sugar levels are controlled, and at what stage the condition is detected and treated. Diabetic retinopathy is a progressive disease, meaning it typically gets worse over time if left unmanaged. However, the progression can be slowed significantly or even stopped with proper diabetes management and timely treatment.^[3]

Not everyone with diabetes will develop retinopathy, but the risk increases with disease duration. Over time, more than half of people with diabetes will develop some form of diabetic retinopathy. The longer you have diabetes, the greater your risk becomes. Those who can better control their blood sugar levels tend to experience slower onset and progression of the disease.^[2]

When caught early, before significant damage has occurred, the prognosis is generally favorable. Background or early-stage nonproliferative diabetic retinopathy often requires only monitoring rather than immediate treatment. With good diabetes management and regular eye screening, many people with early-stage disease maintain good vision for many years. The key is consistent follow-up to detect any progression that might require intervention.^[5]

Poor blood sugar control, high blood pressure, high cholesterol, and long disease duration all worsen the prognosis. These factors accelerate damage to retinal blood vessels and increase the likelihood of progression to more advanced stages. Conversely, managing these risk factors through lifestyle changes, medication adherence, and regular medical care improves outcomes significantly.^[3]

If diabetic retinopathy progresses to the proliferative stage without treatment, the prognosis for vision becomes more serious. Proliferative diabetic retinopathy can lead to severe vision loss and blindness due to bleeding into the eye, retinal detachment, or development of glaucoma. However, even at this advanced stage, treatment can often prevent further vision loss or improve vision in many cases, especially when started promptly.^[6]

Diabetic retinopathy can lead to other serious eye complications that affect prognosis. About one in 15 people with diabetes will develop diabetic macular edema over time, which causes blurry central vision. The condition can also cause abnormal blood vessels to grow and block fluid drainage from the eye, leading to neovascular glaucoma. Scar tissue formation can pull the retina away from the back of the eye, causing tractional retinal detachment. Each of these complications can impact vision outcomes if not treated appropriately.^[2]

It is important to understand that while treatments can prevent or delay vision loss, sight loss that has already occurred due to diabetic retinopathy cannot be reversed. This is why early detection through regular screening and prompt treatment of any progression are so critical to preserving vision.^[5]

Survival rate

Diabetic retinopathy itself is not a life-threatening condition, so survival rates are not typically discussed in relation to this disease. However, it is a serious complication of diabetes that signals broader health concerns. The presence of diabetic retinopathy often indicates that diabetes has been affecting blood vessels throughout the body for some time, which can impact overall health and longevity.

While diabetic retinopathy does not directly cause death, it is associated with increased risk of other serious diabetes complications that can affect survival. These include cardiovascular disease, kidney disease, and stroke. People with poorly controlled diabetes who develop retinopathy may also have damage occurring in blood vessels serving the heart, kidneys, and other vital organs.^[3]

The focus with diabetic retinopathy is on preventing blindness and vision loss rather than mortality. Diabetic retinopathy is the leading cause of blindness in working-age adults, and without treatment, it can cause severe vision loss and permanent blindness. However, with proper screening, timely treatment, and good diabetes management, most people can preserve their vision and maintain quality of life.^[6]

#1 Clinical Trials Search in Europe