How Diabetic Retinopathy Progresses

Medically Reviewed By William C. Lloyd III, MD, FACS
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Diabetic retinopathy is a complication of diabetes. High blood sugar levels damage small blood vessels throughout the body, including the eyes. Diabetic retinopathy occurs when the damage affects tiny blood vessels supplying the retina—the light-sensing tissue at the back of the eye. In the early stages, there usually aren’t any symptoms, but a doctor can find the condition during an eye exam. Diabetic retinopathy progression can lead to vision problems and eventually blindness.

The longer you have diabetes, the greater the risk of developing diabetic retinopathy. In fact, nearly all people with type 1 diabetes will develop some amount of retinopathy within the first 20 years of having the disease. In type 2 diabetes, the number is greater than 60%. The risk also increases when your blood sugar levels are not well controlled.

Stages of Diabetic Retinopathy

Diabetic retinopathy grading depends on the results of a retinal exam. Eye doctors classify it into two main stages, with further gradings within the first stage.

Non-Proliferative Diabetic Retinopathy

The first stage is non-proliferative diabetic retinopathy (NPDR). Non-proliferative means new blood vessels aren’t growing yet. Very early in the disease, symptoms may not be present. As the disease progresses, vision changes will be noticeable and can worsen.

This stage has three sub-stages based on what an eye doctor sees in your retina:

  • Mild NPDR has retinal blood vessels with microaneurysms. Aneurysms are bulges or balloon-like swellings in a vessel wall. They happen when the area in the vessel wall becomes weak or damaged. Blood vessels with aneurysms can leak fluid or blood into the retina. As fluid collects, the retina swells, which can cause vision changes.
  • Moderate NPDR occurs when some blood vessels close off. This deprives the retina of blood supply in that area. Small areas of bleeding and collections of fluid and cells—or exudates—can begin to accumulate.
  • Severe NPDR develops when more and more blood vessels become blocked. Several areas of the retina lose blood supply. This triggers messages to tell the body to make more blood vessels in an attempt to maintain nourishment to the retina.

Proliferative Diabetic Retinopathy

The second main stage is proliferative diabetic retinopathy (PDR). PDR represents advanced diabetic eye disease. Most experts consider this the fourth stage of diabetic retinopathy. Some may break it into two sub-stages.

With proliferative diabetic retinopathy, the retina starts growing new blood vessels in a process called neovascularization. It’s the body’s response to a lack of blood supply to the retina. However, the new vessels grow abnormally and are fragile and unstable. They have a tendency to bleed into the vitreous—the clear gel that fills the eye. Small bleeds can cause dark floaters in your vision. Larger bleeds can quickly block your vision.

When the new blood vessels bleed, they also form scar tissue as they heal. The scar tissue organizes into membranes that can pull on the retina and distort it. Eventually, enough membrane traction can cause retinal detachment, which is a medical emergency. Scar tissue can also interfere with the normal flow of fluid through the eye. This can result in glaucoma. Both of these consequences can lead to permanent blindness. In fact, diabetic retinopathy is a leading cause of blindness in adults up to 74 years of age.

Risk of Progression

People with diabetes should have a dilated eye exam to look at the retina on a regular basis. Adults with type 2 diabetes should have one as soon as they know they have diabetes. About 21% of these patients have some degree of retinopathy at diagnosis. In fact, adults often find out they may have diabetes because of the results of an eye exam. Your doctor will let you know how often you need to repeat a dilated eye exam based on what the first one reveals.

In general, people with mild NPDR have a 6% chance of progressing to PDR within 12 months. With moderate NPDR, the risk of progression within 12 months is 20 to 40%. When you have severe NPDR, your chances of developing PDR within 12 months are higher than 60%.

Diabetic Retinopathy Treatment

Fortunately, there are steps you can take to slow the progression of diabetic retinopathy. Two of the most important things you can do are to control your blood sugar and control high blood pressure if you have it.

Research from the landmark DCCT (Diabetes Control and Complications Trial) looked at the risk and progression of retinopathy. Results suggest that intensive blood sugar control can reduce the risk of retinopathy by 76% in people who do not have it at baseline. In those with mild to moderate retinopathy at baseline, intensive control can reduce the risk of progression by 54%. Similar research into tight control of blood pressure shows it can reduce the risk of retinopathy progression by 34%.

If your doctor decides treatment is necessary, your options may include:

  • Eye injections with vascular endothelial growth factor (VEGF) inhibitors may stop the formation of new blood vessels (neovascularization).
  • Laser photocoagulation can slow or stop the leakage of fluid and blood into the eye.
  • Panretinal photocoagulation can help shrink abnormal blood vessels.
  • Vitrectomy is a procedure to remove blood from the vitreous and scar tissue from inside the eye and replace it with clear sterile fluid, sterile oil, or an inert gas. This operation can help protect the retina from future problems.

After treatment, you will still need regular eye exams to monitor your retinopathy. It’s still possible to have future problems and vision loss. Contact your doctor right away if you have sudden vision changes.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Aug 17
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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