Proliferative Diabetic Retinopathy: Causes and Treatment

Diabetes affects far more than blood sugar levels. Over time, high blood sugar levels can quietly damage the tiny blood vessels lining the back of your eye, and in its advanced stage, this process is known as proliferative diabetic retinopathy. Understanding this condition, what drives it, and what treatment involves can make a real difference to your eye health.

This guide explains how proliferative diabetic retinopathy develops from earlier stages of diabetic eye disease, the risk factors involved, and what happens once it is diagnosed.

Quick Overview

Proliferative diabetic retinopathy (PDR) is the advanced stage of diabetic retinopathy, marked by abnormal new blood vessels growing on the retina.
It develops after non-proliferative diabetic retinopathy, the earlier stage where retinal blood vessels leak and weaken.
Poor blood sugar control, high blood pressure, and longer duration of diabetes are the main risk factors for disease progression.
Laser treatment and, in more advanced cases, retinal surgery are used to manage PDR and reduce the risk of severe vision loss.

The sections below cover how PDR develops, the risk factors involved, the symptoms to watch for, and the treatment options your eye specialist may discuss with you.

How Diabetic Retinopathy Progresses to Its Proliferative Stage

Diabetic retinopathy does not appear suddenly in its most serious form. It develops in stages, starting with non-proliferative diabetic retinopathy, where the retinal blood vessels begin to weaken and leak under the strain of prolonged high blood sugar.

What happens in the non-proliferative stage

In these early stages, tiny blood vessels in the retina develop small bulges and begin leaking fluid or blood. This often causes no noticeable vision problems at first. That is exactly why regular eye examinations matter, even when your sight feels completely normal.

A diagnosis of non-proliferative retinopathy at this point does not mean it will get worse. With good medical control of blood sugar and blood pressure, many adults stay at this stage for years, or the condition improves.

One complication can develop alongside this stage: diabetic macular edema, also called diabetic macular oedema. This happens when leaking fluid causes swelling in the macula, the part of your retina responsible for sharp central vision, and it can blur or distort what you see directly in front of you.

The shift to proliferative diabetic retinopathy

Over time, more and more damaged blood vessels and leaking blood vessels appear throughout the retina. Parts of the retina start running low on oxygen. Your eye tries to fix this the only way it knows how: by growing new blood vessels, in a process called retinal neovascularisation.

This is where the real trouble starts. These new vessels are weak and poorly formed. They grow on the surface of the retina and sometimes push into the vitreous gel, the clear jelly that fills the middle of your eye. This stage, where these fragile new vessels appear, is what doctors call proliferative diabetic retinopathy (PDR).

The problem is that these new vessels are not a real fix. Clinical guidance confirms that fragile new vessels bleed easily. When one breaks, blood spills into the vitreous cavity, the main fluid-filled space inside your eye. This is called a vitreous haemorrhage, and it can cloud your vision suddenly, sometimes within hours.

What Increases the Risk of Developing PDR

Anyone with diabetes faces some risk of developing diabetic retinopathy. Whether it progresses to the more serious proliferative stage depends on a handful of factors. Here is what matters most.

Blood sugar control is the biggest factor. The research is consistent on this: the better your blood sugar is managed over time, the lower your risk of progression.

Blood pressure matters just as much. High blood pressure puts extra strain on retinal blood vessels that are already under pressure from diabetes. Recent research confirms that blood pressure is an independent predictor of diabetic retinopathy progression, alongside other cardiovascular risk factors.

How long you have had diabetes counts too. Clinical guidance confirms that risk increases with diabetes duration, regardless of how well it has been managed along the way. This applies whether you have type 1 or type 2 diabetes.

A few other factors add to the risk: high cholesterol, smoking, and pregnancy in women who already have diabetes. Genetics may also play a small role, since some families show a higher rate of eye complications even with good blood sugar and blood pressure control, though researchers do not yet fully understand why.

Recognising the Symptoms

Vision changes from proliferative diabetic retinopathy can develop gradually or, in some cases, quite suddenly.

Blurred vision, new floaters, or dark spots drifting across your visual field can all signal bleeding from abnormal new blood vessels. A sudden, significant drop in visual acuity in one or both eyes may indicate a more substantial vitreous haemorrhage or the early stages of retinal detachment, where the retina pulls away from the back of the eye as fibrous bands form scar tissue around the fragile new vessels.

You might also notice difficulty with night vision or gaps and shadows appearing in your visual field as the condition progresses. A sensation of a curtain or shadow moving across part of your vision can indicate a more significant retinal detachment and should prompt urgent assessment rather than waiting for a routine appointment. Importantly, many individuals with diabetic eye disease, including some with proliferative retinopathy, experience no symptoms at all until the disease has reached an advanced stage, which underscores why eye examinations matter regardless of how your vision feels day to day.

How PDR Is Diagnosed

A dilated fundus examination is the standard way an eye specialist checks for diabetic retinopathy. Eye drops widen the pupil, allowing a detailed view of the retina, the optic disc, and the blood vessels in the retina.

Optical coherence tomography is often used alongside this examination, producing detailed cross-sectional images that reveal swelling, leaking fluid, or areas of macular oedema that might not be visible during a standard examination alone. Together, these tools allow an eye specialist to determine the stage of diabetic retinopathy and plan appropriate treatment.

Treatment Options for Proliferative Diabetic Retinopathy

Once a diagnosis of proliferative diabetic retinopathy (PDR) is confirmed, treatment generally involves one or a combination of approaches, depending on severity and how the disease is progressing.

Laser treatment

Laser therapy, specifically panretinal laser treatment, is a long-established approach for PDR. It works by targeting areas of the retina that are not receiving enough blood supply, reducing the drive behind abnormal blood vessel growth and helping to reduce swelling in nearby tissue. Research confirms that laser treatment cuts severe vision loss by more than half when performed on eyes with high-risk PDR. While laser surgery can slow disease progression considerably, it does not reverse damage that has already occurred, which is part of why early treatment matters so much.

Anti-VEGF injections

Vascular endothelial growth factor is the substance the body produces in response to the oxygen-starved retina, and it is largely responsible for triggering new blood vessel growth. Medications that block this substance are injected directly into the eye and are commonly used both for PDR and for diabetic macular edema.

Retinal surgery

For more advanced cases involving significant vitreous hemorrhage, scar tissue, or tractional retinal detachment, retinal surgery may be required. Known as a vitrectomy, this procedure removes blood and scar tissue from the eye and addresses any retinal detachment directly, aiming to preserve as much vision as possible. Recovery from retinal surgery varies depending on the extent of the disease, and your eye specialist will discuss what to expect during your specific procedure and the follow-up appointments that typically come afterwards.

Neovascular Glaucoma: A Serious Complication of Advanced PDR

When proliferative diabetic retinopathy reaches a more advanced stage without adequate treatment, abnormal blood vessels can begin growing in parts of the eye well beyond the retina itself.

How neovascular glaucoma develops

In advanced diabetic retinopathy, the same oxygen-starved retina that triggers neovascularisation can also drive abnormal blood vessel growth on the iris, the coloured part of the eye, and into the eye’s drainage angle. When this happens, these vessels can block the normal outflow of fluid from the eye, causing intraocular pressure to rise sharply. This condition is known as neovascular glaucoma, and it represents one of the more serious complications associated with severe cases of PDR.

Why this matters for your vision

Neovascular glaucoma can progress quickly and is more difficult to manage than other forms of glaucoma, making early detection of the underlying proliferative diabetic retinopathy especially important. Left unmanaged, it can contribute to severe visual loss on top of any damage already caused by vitreous haemorrhage or tractional retinal detachment. Treating PDR before it progresses to this advanced stage is one of the clearest reasons early treatment matters so much.

Why Early Treatment and Regular Eye Exams Matter

Severe vision loss from proliferative diabetic retinopathy is largely preventable with early diagnosis and timely treatment. Diabetic eye disease at its earliest stages often produces no symptoms, which makes scheduled eye examinations, not waiting for vision changes, the most reliable way to catch disease progression before it reaches a more advanced stage. Early detection consistently leads to better outcomes than waiting until decreased vision becomes noticeable, since the light-sensitive tissue at the back of the eye does not repair itself once significant damage has occurred.

Those with diabetes lose vision unnecessarily in many cases where retinopathy was not caught and treated early, but rather left until symptoms appear. When PDR is treated early, before extensive scar tissue has had the chance to form around fragile vessels, the likelihood of preserving useful vision improves considerably. The goal throughout treatment remains the same: to prevent vision loss before the disease threatens your sight permanently.

Beyond the eyes, the same vascular damage driving PDR is connected to broader diabetic complications, including elevated risk of conditions like myocardial infarction. Managing blood pressure and cholesterol alongside blood sugar levels supports both eye health and overall cardiovascular health, since the abnormal blood vessels seen in the eye reflect the same vascular processes occurring throughout the body.

Living With Diabetes? Protect Your Vision With Regular Eye Care

Diabetic eye disease can progress without obvious symptoms, which makes regular eye examinations one of the most valuable steps you can take if you live with diabetes. A comprehensive examination looks well beyond a standard vision check, assessing the retina directly for the early signs of damage long before you would notice any change yourself.

The team at Armadale Eye Clinic can talk you through your individual risk factors and how often you should be screened based on your specific situation.

To book a comprehensive eye examination or discuss your risk of diabetic retinopathy, please call us on (03) 9070 5753.

Frequently Asked Questions

How often should someone with diabetes have an eye exam?

An eye examination at least once a year is recommended for those living with diabetes, though this can increase to every three to six months if retinopathy has already been detected or risk factors are elevated. Pregnant women with pre-existing diabetes are often advised to have more frequent reviews due to the accelerated risk of progression during pregnancy. Your eye specialist will set a personalised schedule based on your specific findings.

Can proliferative diabetic retinopathy affect only one eye?

While diabetic retinopathy often progresses in both eyes simultaneously, it is possible for one eye to be more severely affected than the other at any given time. This is one reason a comprehensive eye examination always assesses both eyes individually rather than assuming symmetry. If you notice vision changes in one eye specifically, this still warrants the same urgency as changes affecting both.

Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

References

https://www.healthdirect.gov.au/diabetic-retinopathy

https://www.mdfoundation.com.au/about-macular-disease/diabetic-eye-disease/other-risk-factors/

Proliferative Diabetic Retinopathy: What Happens When Diabetic Eye Disease Reaches Its Advanced Stage