Diabetic Retinopathy Stages: What Each One Means

If you live with diabetes, you have probably been told your eyes need checking every couple of years. What is less often explained is what the check is actually looking for. Diabetic retinopathy stages describe how far the condition has moved along a path that starts with no symptoms at all. The stage you are given decides how often you are seen and whether treatment is needed. Knowing what each stage means makes the results of your next eye check far easier to follow. In this blog post, we cover what causes the condition, how the stages are graded, what happens at each one, and how each stage is treated.

Quick Overview

• Diabetic retinopathy is damage to the small blood vessels of the retina caused by high blood glucose over time.
• The stages divide into non-proliferative diabetic retinopathy, where vessels leak and become blocked, and proliferative diabetic retinopathy, where fragile new blood vessels grow.
• Diabetic macular edema is graded separately, because it can appear at any stage and follow its own course.
• Early stages usually cause no symptoms, so the stage is found on examination rather than by how your vision feels.

We will start with what is happening inside the retina, because the stages are simply a description of how far that process has gone.

What Causes Diabetic Retinopathy?

Diabetes mellitus affects small blood vessels throughout the body, and the retina is one of the places where that damage can be seen directly. The retina is the light-sensing layer at the back of your eye, and it depends on a dense network of retinal capillaries to supply it.

High blood glucose over years weakens those capillary walls. Some balloon outwards into tiny bulges called microaneurysms. Others leak fluid and blood into the surrounding retina. Others close off completely, so the tissue they used to supply stops receiving enough blood. That loss of supply is retinal ischemia.

Retinal ischemia is what drives the later stages. When enough of the retina is starved of blood, it releases chemical signals asking for new vessels to be built. Those new blood vessels are the defining feature of the advanced stage, and they cause more problems than they solve.

Diabetic retinopathy is a complication of these small blood vessels, and it is common. A review of the systems used to classify the disease notes that it occurs in about 30% of those with diabetes. It remains a leading cause of preventable vision impairment in adults.

How Are the Stages of Diabetic Retinopathy Graded?

There are five recognised stages. Grading is based on what an eye doctor can see in your retina, not on how your vision feels.

The scale is used internationally, so the stage recorded at your appointment means the same thing anywhere. It came out of long-running research programmes, including the Diabetic Retinopathy Study and the Early Treatment Diabetic Retinopathy Study. Those studies photographed thousands of eyes over years and worked out which fundus photographic risk factors predicted trouble ahead. Grading diabetic retinopathy this way means your stage tells you something about risk, rather than just describing today.

The five stages are no apparent retinopathy, then mild, moderate and severe nonproliferative diabetic retinopathy, then proliferative diabetic retinopathy. We will take each in turn.

Stage 1: Mild Non-Proliferative Diabetic Retinopathy

Mild diabetic retinopathy is the earliest change that can be seen. It is defined by microaneurysms alone, with nothing else present.

Research on imaging that detects change early notes that a diagnosis of mild non-proliferative diabetic retinopathy is made once at least one microaneurysm is found. That is a very small finding. It causes no symptoms, and vision is usually completely normal.

This stage matters because it is a marker rather than a problem in itself. It tells you the process has started. It is also the stage at which changes to blood glucose, blood pressure and cholesterol have the greatest chance of altering what happens next. Sometimes called background diabetic retinopathy, this stage generally needs monitoring rather than treatment. Your ophthalmologist records it, sets a review interval, and compares the images at your next visit to see whether anything has shifted.

Stage 2: Moderate Non-Proliferative Diabetic Retinopathy

Moderate non-proliferative diabetic retinopathy sits between mild and severe, and its definition reflects that. It means more than just microaneurysms, but not yet enough to meet the criteria for severe disease.

In practice, this stage brings a wider range of retinal findings. Retinal hemorrhages appear as small dots or blots where vessels have bled. Hard exudates show up as yellowish deposits of fat and protein that have leaked out. Cotton wool spots appear as pale patches where nerve fibres have lost their blood supply. Some retinal capillaries have closed, so retinal blood flow to parts of the retina is starting to fall.

Vision is often still normal at this stage, or only slightly affected. Blurred vision, where it does appear, usually comes from fluid at the macula rather than from the stage itself. What changes is the monitoring interval. Moderate disease is watched more closely than mild, because the risk of moving up a stage is higher.

Stage 3: Severe Non-Proliferative Diabetic Retinopathy

Severe non-proliferative diabetic retinopathy means widespread vessel closure, with the retina now significantly short of blood, but no new vessels yet.

The criteria are specific. Severe disease is diagnosed when an eye shows any one of the following, with no proliferative changes present:

• More than 20 retinal hemorrhages in each of the four quadrants of the retina
• Clear venous beading, meaning veins that look like a string of sausages, in two or more quadrants
• Prominent intraretinal microvascular abnormalities in at least one quadrant

Those abnormalities, often shortened to IRMA, are small irregular vessels that have opened up inside the retina to bypass blocked capillaries.

This is the stage where the risk of progression rises sharply. The retina is now signalling for new vessel growth, and treatment is often discussed here rather than after the new vessels arrive.

Stage 4: Proliferative Diabetic Retinopathy

Proliferative diabetic retinopathy is the advanced stage. It is defined by new blood vessels growing on the retina or the optic disc. It is also diagnosed when there is bleeding in front of the retina, or into the vitreous gel that fills the eye.

The new vessels are the problem. They grow in response to retinal ischemia, but they are fragile and poorly built. When they bleed into the gel, the result is a vitreous haemorrhage, which can cause sudden floaters or a dark curtain across the vision. Over time, the vessels are accompanied by scar tissue, and when that scar tissue contracts, it can pull the retina away from the back of the eye. That is a tractional retinal detachment, and it differs from a rhegmatogenous retinal detachment, which happens when the retina tears.

New vessels can also grow on the iris and block the eye’s drainage channels, causing pressure to rise. This is neovascular glaucoma, and it needs prompt treatment because raised pressure damages the optic nerve. Vision-threatening diabetic retinopathy is the term used for the stages carrying serious risk to sight, and proliferative disease sits firmly within it.

Where Does Diabetic Macular Edema Fit?

Diabetic macular oedema does not belong to any single stage. It is graded separately, and it can appear alongside mild, moderate, severe or proliferative disease.

The macula is the small central part of the retina you use for reading and recognising faces. When leaking vessels allow fluid to collect there, the tissue swells. That swelling is retinal oedema, and the resulting retinal thickening is what an eye examination measures. Guidance from Diabetes Australia on the stages notes that macular oedema can be found with any stage of diabetic retinopathy and can run an independent course.

There is also a specific threshold, called clinically significant macular oedema. It describes swelling that sits close enough to the centre of the macula to matter for your sight. The threshold was set in the research that first showed laser treatment helped this group, and it is still referred to today. Diabetic macular oedema is now the leading cause of vision loss in diabetic retinopathy, which is why it is assessed at every review regardless of your overall stage.

How Are the Stages Diagnosed?

Staging is done by looking at the retina and by measuring it. Symptoms are not part of the grading, because the early stages do not produce any.

A diabetic eye check starts with a dilated fundus examination. Drops widen the pupil so the whole retina can be seen, then a photograph is taken. Optical coherence tomography adds a cross-sectional scan through the macula. It measures retinal thickening in microns, which are thousandths of a millimetre, and it is how macular oedema is graded and monitored.

Two further tests are used when more detail is needed. Fluorescein angiography involves injecting a dye into a vein in your arm and photographing it as it passes through the retinal vessels. It shows exactly where capillaries have closed and where new vessels are leaking. Optical coherence tomography angiography maps the same vessels without any dye, and can pick up changes before anything is visible on a standard photograph. Between them, these tests produce the retinal findings that decide your stage. Repeating the same tests over time is how progression is measured.

What Treatment Is Used at Each Stage?

Treatment follows your stage rather than your symptoms. In the earlier stages, it usually means managing your diabetes rather than treating the eye.

For mild and moderate disease, the approach is monitoring plus blood sugar management. Keeping blood glucose levels, blood pressure and cholesterol close to target slows progression. No eye procedure is normally needed.

For severe nonproliferative and proliferative disease, laser treatment comes in. A laser is applied across the outer retina to reduce the demand for new vessels, which lowers the risk of serious vision loss. This is called panretinal photocoagulation.

Macular oedema is treated differently. Laser was the original approach, and injections into the eye are now the mainstay. The injections block a chemical signal called vascular endothelial growth factor, or VEGF. It drives both the leaking and the growth of new vessels.

Two things are worth knowing about the injections. They do not work fully for everyone, and roughly 40 to 50% of eyes with macular oedema get an incomplete response. They also do not fix the poor blood supply underneath, so swelling can return if treatment stops. Newer medicines aimed at other pathways have reached phase III trials, which are the large studies run before a treatment is approved for use.

Vitrectomy surgery is used in the advanced stages. It is an operation inside the eye, and it is used when a vitreous haemorrhage will not clear, or when scar tissue has caused a tractional retinal detachment.

What Affects How Fast the Stages Progress?

Two patients at the same stage can move at very different speeds, and several factors explain the difference.

• How long you have had diabetes. Duration carries risk independently of everything else.
• Glycemic control. Long-running high blood glucose accelerates progression. This applies to type II diabetes and to insulin-dependent diabetes mellitus alike.
• Blood pressure and cholesterol. Both influence how quickly retinopathy advances, which is why diabetes care covers all three.
• Pregnancy. It can change the pace of progression, so monitoring is usually increased.
• Other systemic diseases. Kidney disease in particular tends to travel alongside diabetic eye disease.

None of these are reasons for alarm on their own. They are the reasons the interval between your checks is set individually rather than by a single rule.

Book a Diabetic Eye Check at Our Clinic

The stages of diabetic retinopathy exist because the condition is silent until it is not, and the interval between your eye checks does more to protect your sight than any symptom you might notice. Retinal imaging and macular scanning can identify a change of stage while it is still quiet, well before a vitreous haemorrhage.

At Mornington Peninsula Eye Clinic, our retinal ophthalmologists assess and manage diabetic retinopathy and diabetic macular oedema using retinal imaging, intravitreal injections, retinal laser and vitreoretinal surgery. Whether you have been referred with retinal changes, are due for a review, or have noticed a change in your vision, we are glad to help. To arrange a consultation at our eye clinic, please call us on (03) 9070 3580.

Frequently Asked Questions

Can diabetic retinopathy improve or go back a stage?

Sometimes the recorded stage does improve, particularly after injections, because the visible lesions used for grading can settle. That is not quite the same as the underlying disease reversing, since the reduced blood supply behind it remains. It is one reason your stage is read alongside your history rather than on its own.

Why does my vision seem to fluctuate from day to day?

High blood glucose temporarily changes the shape of the lens inside your eye, which blurs vision until levels settle. This is separate from retinopathy and often happens around diagnosis or when control shifts. It is also why a new glasses prescription is usually delayed until your glucose has been stable for a while.

Does pregnancy change how often my eyes need checking?

Yes, usually. Pregnancy is one of the factors that can alter the pace of retinopathy, so checks are typically scheduled more frequently through it. If you are planning a pregnancy, raising it before you conceive gives time for a baseline examination.

How long does a diabetic eye check take, and can I drive afterwards?

Allow around half an hour. The dilating drops leave you sensitive to light for a few hours and blur near vision. Bring sunglasses, and arrange another way home rather than planning to drive yourself.

Can I have a different stage in each eye?

Yes, and it is common. The two eyes are graded separately because the pattern of vessel damage is rarely identical. Your management follows the worse eye, while the better one continues to be monitored on the same schedule.

If I have had diabetes for years with no retinopathy, am I in the clear?

No, though it is a good sign. Risk continues to accumulate with duration, so screening carries on regardless of how many clear checks you have had. Some patients develop their first changes after two decades without any.

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

References

https://www.keepsight.org.au/eye_health_diabetes

https://my.clevelandclinic.org/health/diseases/8591-diabetic-retinopathy