Diabetic Retinopathy, Explained

Diabetic retinopathy is damage to the tiny blood vessels of the retina — the light-sensitive tissue at the back of the eye — that can develop when blood glucose stays high over time. It is a leading cause of vision loss in working-age adults, and it frequently causes no symptoms early on. That silence is exactly why regular dilated eye exams matter so much.

What happens in the retina

The retina is nourished by a network of very small blood vessels. Prolonged high glucose can weaken and damage these vessels, causing them to leak fluid or blood, or to close off. As the eye tries to compensate, it can grow fragile new vessels that cause further problems. Because this is damage to small vessels, retinopathy sits alongside kidney and nerve disease among the microvascular complications of type 2 diabetes. See the type 2 diabetes hub for the wider context.

Why it is often silent

In its early stages, diabetic retinopathy often produces no noticeable symptoms. Vision can seem completely normal while changes are already underway in the retina. When symptoms do appear, they may include blurred or fluctuating vision, dark or empty areas, spots or "floaters," or difficulty seeing at night. Because the early phase is silent, waiting for symptoms is not a safe strategy — the National Eye Institute (NEI) recommends regular dilated eye exams, which let a specialist see the retina directly and catch changes before vision is affected.

The stages of retinopathy

Retinopathy is usually described in stages that reflect how advanced the vessel damage is:

• Nonproliferative diabetic retinopathy (NPDR): the earlier stages, ranging from mild to severe, in which vessels weaken, may leak, and can develop small bulges. Vision is often still normal.
• Proliferative diabetic retinopathy (PDR): a more advanced stage in which fragile new blood vessels grow, raising the risk of bleeding and other serious problems that can threaten vision.

Macular edema

At any stage, fluid can build up in the macula — the central part of the retina responsible for sharp, straight-ahead vision. This is called diabetic macular edema, and because it affects central vision it can interfere with reading, recognising faces, and other everyday tasks. It is a common reason vision is affected in diabetes and can be present even when other retinopathy is not advanced.

Protecting vision

The encouraging message from the NEI and the American Diabetes Association (ADA) is that vision can often be protected. Managing blood glucose and blood pressure reduces the risk of retinopathy developing and progressing, and timely eye care — regular dilated exams and treatment when it is needed — makes a meaningful difference to outcomes. Detected early, retinopathy can often be managed before serious vision loss occurs. Endobits is clinical decision-support software used under clinician oversight; it can help organise and interpret glucose data that informs a care plan, but it does not diagnose or treat, and eye care should always be directed by a qualified clinician.

Sources

National Eye Institute (NEI) — Diabetic Retinopathy. American Diabetes Association — Eye Health & Diabetes. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) — Diabetic Eye Disease.

Related: The type 2 diabetes guide · Complications of type 2 diabetes · Diabetic neuropathy · Diabetic kidney disease · Glossary