High blood sugar levels resulting from diabetes can lead to diabetic retinopathy (DR), which may damage the blood vessels in the retina. In severe cases, this results in the growth of new, abnormal vessels, which is known as neovascularization.

People living with diabetes must carefully monitor their blood sugar levels and keep them within suitable ranges. If a person is unable to manage their blood sugars, they may begin to experience health complications, such as DR. This refers to blood vessel damage in the retina that can affect vision.

DR affects a large number of people living with diabetes. The Centers for Disease Control and Prevention (CDC) note that it may affect up to a third of adults over the age of 40 living with diabetes.

A person may not notice symptoms of DR at first, but as it progresses, it can lead to visual impairment and the growth of new and abnormal blood vessels in the retina.

In this article, we will review what neovascularization is, why it occurs in DR, and how to prevent or delay it from occurring in DR.

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Neovascularization is a term that refers to the development of new and abnormal blood vessels that grow from within the retina toward the center of the eye.

It often occurs during the latter, or more advanced, stages of DR. As these new blood vessels are not healthy, they are prone to leaking or hemorrhaging. This can lead to vision issues, such as seeing dark spots, and visual impairment.

Experts note that neovascularization occurs in the final and most severe stage of DR, known as proliferative diabetic retinopathy (PDR). The defining characteristic of PDR is the presence of new, or proliferating, blood vessels. Health experts may use the term neovascularization to describe these blood vessels.

At this stage in the condition, the retina releases vascular endothelial growth factor (VEGF) to try to improve blood circulation in the retina. VEGF is a protein that stimulates the formation of new blood vessels. However, these blood vessels are fragile and can leak blood into the back of the eye and block vision.

A treatment option to slow or reverse DR involves the injection of anti-VEGF medication. Evidence notes that these medications can play an important role in improving the overall outcome for DR and preventing further complications.

There are two main types of DR. Doctors refer to these as nonproliferative diabetic retinopathy (NPDR) and PDR. They can then further classify DR into 4 stages with increasing severity.


NPDR refers to the early stages of the condition. The first 3 stages of DR are types of NPDR with increasing severity. Many people living with diabetes have this type of DR. It often causes blurry vision.

During these stages, a doctor will be able to identify the presence of tiny bulges in the retina’s blood vessels. These areas of swelling are known as microaneurysms.

As the condition progresses, further damage and blockages occur in larger sections of blood vessels in the retina. This causes a significant decrease in blood flow to this area.


PDR is the more advanced stage of DR. The defining feature of PDR is the presence of new, fragile blood vessels.

The new blood vessels tend to leak and may also cause scar tissue to form. This can result in the retina detaching or additional issues with the macula. PDR can cause severe vision loss and blindness if a person does not get treatment.

DR affects a person’s vision. It can lead to vision issues that include:

  • losing vision
  • seeing an increasing number of floaters
  • having vision that changes from blurry to clear
  • having blurry vision
  • noticing colors appearing washed out or faded
  • having poor night vision
  • seeing blank or dark areas in the field of vision

DR is a common occurrence in people living with diabetes. Several factors increase the likelihood of developing DR. They include:

  • higher A1c levels
  • insulin use
  • male sex
  • longer duration of diabetes
  • higher systolic blood pressure

A person can take steps to help prevent DR. The CDC recommend two methods. First, a person should take care to manage their blood sugar levels. This can include:

  • following a diabetic diet plan
  • taking regular exercise
  • checking blood sugar levels frequently and following a doctor’s recommendations for timing
  • taking insulin or medications as a doctor prescribes

The CDC also recommend a person living with diabetes get regular eye exams. This can help doctors catch issues with the eyes earlier, which may improve treatment outcomes and overall outlook.

A person should also contact an optometrist, an eye doctor, or a doctor treating their diabetes if they notice vision changes because this can indicate DR.

Click here to learn more about diabetic eye screening.

DR is a common cause of vision impairment and blindness in people living with diabetes. In the early stages, it can cause blurry vision and other changes in vision. In later stages, it may cause partial or full loss of vision.

Neovascularization refers to the formation of new, fragile blood vessels in the eye. It is the defining characteristic of the final stage of DR.

A person can help prevent DR from occurring by managing their blood sugar and blood pressure levels. Additionally, it is also advisable for a person living with diabetes to attend regular eye exams so a doctor can assess their eyes. A person should contact their doctor if they notice any changes to their vision.