Proliferative diabetic retinopathy (PDR) is the most advanced and serious stage of diabetic eye disease, where new, abnormal blood vessels grow on the surface of the retina. These fragile vessels can bleed into the eye or pull the retina out of position, leading to severe vision loss or blindness. About 3.7% of people with diabetes develop PDR, making it relatively uncommon but one of the leading causes of preventable blindness in working-age adults.
How PDR Develops
Diabetic retinopathy progresses through stages. In the earlier, nonproliferative stage, high blood sugar damages the tiny blood vessels that nourish the retina. These vessels weaken, bulge, and leak fluid. Over time, some of them close off entirely, cutting off blood supply to patches of retinal tissue.
When enough vessels shut down, parts of the retina become starved of oxygen. This is where PDR begins. The oxygen-deprived retina sends out chemical distress signals, most importantly a protein called VEGF (vascular endothelial growth factor). VEGF tells the body to grow new blood vessels to restore circulation. The problem is that these emergency replacement vessels are structurally defective. They’re thin-walled, leaky, and grow in the wrong places, often extending from the retina’s surface into the gel-like fluid (vitreous) that fills the center of the eye. Scar tissue typically forms alongside them, creating fibrous membranes that attach to both the retina and the vitreous.
Symptoms and Warning Signs
PDR can develop silently. Many people have no symptoms until a complication occurs, which is why screening exams matter so much. When symptoms do appear, they often come on suddenly:
- Floaters or dark spots: New blood vessels are fragile and rupture easily. When they bleed into the vitreous, you may see a shower of dark floaters, cobweb-like streaks, or a sudden reddish tint across your vision.
- Blurred or patchy vision: A larger bleed (vitreous hemorrhage) can partially or completely block light from reaching the retina, causing a dramatic drop in vision over hours or even minutes.
- Distorted or lost vision: The fibrous scar tissue that grows alongside new vessels can contract and pull the retina away from the back wall of the eye. This tractional retinal detachment may cause a shadow or curtain effect in part of your visual field.
A small vitreous hemorrhage sometimes clears on its own over weeks as the blood reabsorbs. But repeated bleeding, progressive scarring, or retinal detachment can cause permanent damage if left untreated.
How PDR Is Diagnosed
An eye doctor can detect PDR during a dilated eye exam, where drops widen your pupils so the retina can be examined directly. The hallmark finding is neovascularization: new blood vessels growing on the optic disc or elsewhere on the retinal surface.
To get a more detailed picture, your doctor may order a fluorescein angiography. In this test, a fluorescent dye is injected into a vein in your arm. As the dye circulates through the retinal blood vessels, a special camera captures images. Abnormal new vessels leak dye visibly, showing up as areas of bright, spreading fluorescence. The test also reveals patches of retina that have lost their blood supply, which appear as dark zones where the dye never arrives. These areas of poor circulation help the doctor gauge how much of the retina is at risk and guide treatment decisions.
Optical coherence tomography (OCT), a painless imaging scan that creates cross-sectional pictures of the retina, is often used alongside angiography to check for fluid buildup or traction on the retina’s layers.
Treatment Options
The goal of treatment is to stop abnormal vessel growth, prevent bleeding, and preserve as much vision as possible. Two main approaches are used, sometimes in combination.
Laser Therapy
Panretinal photocoagulation (PRP) has been the standard treatment for PDR for decades and remains the primary recommendation from national guidelines, including those of the American Academy of Ophthalmology. During PRP, a laser creates hundreds to thousands of tiny burns across the peripheral retina. By intentionally destroying small areas of oxygen-starved tissue, the treatment reduces the retina’s demand for blood supply and lowers the chemical signals driving abnormal vessel growth. PRP is highly effective at preventing severe vision loss, though it can reduce peripheral vision and night vision to some degree because of the tissue it sacrifices.
Anti-VEGF Injections
Because VEGF is the key chemical driving new vessel growth in PDR, medications that block it can slow or reverse the process. These drugs are injected directly into the eye, typically in an office setting with numbing drops. The injections cause the abnormal vessels to shrink and leak less. Anti-VEGF therapy is used as an alternative to laser in some cases or as an add-on treatment. Unlike laser, anti-VEGF injections don’t permanently alter the retina, but they require ongoing treatment since the effect wears off over weeks to months.
Newer medications that target two pathways at once, blocking both VEGF and a second protein that destabilizes blood vessels, are also now available. By addressing vessel instability from a second angle, these dual-action drugs may offer more durable results for some patients, potentially meaning fewer injections over time.
Vitrectomy Surgery
When PDR causes a large vitreous hemorrhage that doesn’t clear on its own, or when scar tissue pulls the retina into a detachment, surgery may be necessary. A vitrectomy removes the blood-filled vitreous gel and any scar tissue, replacing the gel with a clear saline solution or a gas bubble that holds the retina in place while it heals. Recovery time varies, but many people need several weeks before vision stabilizes. If a gas bubble is used, you may need to hold your head in a specific position for days to keep the bubble pressing against the retina.
Risk Factors and Prevention
The longer you have diabetes, the higher your risk of developing PDR. Poor blood sugar control accelerates the process significantly. High blood pressure and high cholesterol also contribute to retinal vessel damage. People with type 1 diabetes generally face a higher lifetime risk because they typically live with the disease longer, but type 2 diabetes accounts for the majority of PDR cases simply because it’s far more common.
The most effective way to prevent PDR is to keep blood sugar, blood pressure, and cholesterol well managed. Studies consistently show that tighter glucose control dramatically reduces the risk of progression from early retinopathy to the proliferative stage.
Screening Recommendations
Because PDR often causes no symptoms until serious damage has occurred, regular eye exams are critical. The American Diabetes Association’s 2025 guidelines recommend the following schedule:
- Type 1 diabetes: First dilated eye exam within 5 years of diagnosis, then annually.
- Type 2 diabetes: First dilated eye exam at the time of diagnosis, then annually.
If your exam shows no signs of retinopathy and your blood sugar is well controlled, your doctor may extend the interval to every 1 to 2 years. If any level of retinopathy is detected, you’ll need at least annual exams, and more frequent visits if the disease is progressing. Catching retinopathy in its earlier stages gives you the widest range of treatment options and the best chance of preserving your vision long term.