The stages of diabetic eye disease

Retinopathy refers to damage to the retina, the layer of light-sensitive cells located in the back of the eyeball. Diabetic retinopathy is damage to the retina caused by having diabetes.

Diabetic retinopathy can occur with type 1 diabetes and type 2 diabetes. It can also occur with gestational diabetes (diabetes that occurs during pregnancy), though this is less common. However, the risk is highest among people who have diabetes prior to becoming pregnant, and eye exams are recommended when planning pregnancy or during the first trimester, with additional exams each trimester to monitor for eye problems.

People who have early stages of diabetic retinopathy may have no symptoms or may only have mild symptoms. People who have the more advanced stages of diabetic retinopathy are likely to experience vision problems, and in some cases, vision loss.

Here, we look at the difference between early-stage diabetic retinopathy and late-stage diabetic retinopathy, including what is happening in the eye during these stages and the symptoms a person might experience.

Non-proliferative diabetic retinopathy

Diabetic retinopathy can be divided into two broad stages or types—non-proliferative diabetic retinopathy and proliferative diabetic retinopathy.

Non-proliferative diabetic retinopathy (NPDR) is the early stage. It occurs when high blood glucose levels damage and weaken the very small blood vessels (called capillaries) that supply the retina with blood.

When these capillaries become weakened and damaged, small pockets of the capillary walls can bulge outward (these are called microaneurysms). Eventually, these bulges can rupture and leak fluid into the retina (called dot and blot hemorrhages).

When fluid leaks into the retina, it can disrupt the eye’s normal functioning and cause damage to the retina. It can also cause macular edema—swelling of the macula, the retina’s central cluster of photoreceptor cells.

As the leaked fluid drains away from the eye, it can leave behind deposits of waxy, yellowish residue (these are called hard exudates). Over time, these can clog capillaries, blocking them off completely. These will be visible during an eye exam.

Blockages can also lead to a type of lesion on the retina called cotton wool spots, which look like flecks of white paint and can be seen during an eye exam. These can be a sign that NPDR is progressing.

NPDR can be classified as mild, moderate, or severe depending on the number and distribution of microaneurysms, dot-and-blot hemorrhages, and cotton wool spots throughout the eye or eyes.

Proliferative diabetic retinopathy

The advanced stage is called proliferative diabetic retinopathy (PDR). This stage occurs when new blood vessels begin to form inside the retina (called neovascularization).

Neovascularization is the body’s attempt to supply the retina with blood after existing blood vessels have become blocked, and normal blood flow to the retina has been reduced. The eye releases a protein called vascular endothelial growth factor (VEGF) that stimulates the growth of new blood vessels.

However, these new blood vessels do not function well—they leak, they are easily damaged, and they can form scar tissue that can further damage the eye. PDR can cause severe and sudden vision loss.

PDR and other conditions can be treated with anti-VEGF medications, which are injected into the eye and block VEGF. Other treatment options are photocoagulation (laser surgery to seal off leaking blood vessels) and surgery to repair damage to the retina.

As with many aspects of treating diabetes, the best choice of treatment for diabetic retinopathy varies from person to person, and your best source of information will be a healthcare provider.

While treatment is different for every person, good diabetes control and getting treated as early as possible are essential to getting the best results.