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Medically reviewed and verified by Kate Burke, MD, MHA
Diabetes remains one of the most common health concerns worldwide. Estimates report that around 10.5% of the world's adult population has the disease! And of that almost half are unaware. This number is only expected to go up. By 2045 the IDF Diabetes Atlas projects that more than 780 million people will be living with diabetes. There are a number of associated health risks that come with having the disease. One of the most significant complications of diabetes is diabetic retinopathy, a condition that can lead to blindness if left untreated. There are a few different stages, but the most advanced and dangerous form is called proliferative diabetic retinopathy (PDR). If you or a loved one has diabetes, understanding PDR and its associated risks is an important part of prevention! Here is a guide from PatientsLikeMe.
What Is Diabetic Retinopathy?
Diabetic retinopathy is a link in the chain that connects diabetes to your eye health. Diabetes is the condition that sits underneath everything and retinopathy is what happens when you have prolonged high blood sugar levels. In fact, after 20 years of having diabetes, 80% of patients with T1D and 53% of patients with T2D will develop some kind of retinopathy! It primarily affects the small blood vessels in the retina, the part of the eye responsible for detecting light and sending visual signals to the brain. Besides having diabetes, there are a few more risk factors to be aware of.
- Duration of diabetes (longer duration, higher risk)
- Poor blood sugar control (high HbA1c levels)
- High blood pressure
- High cholesterol (dyslipidemia)
- Smoking
- Pregnancy (for women with diabetes)
In early stages of diabetic retinopathy the blood vessels in the eye are weakened by blood sugar. Tiny bulges can form, and fluid may leak into the retina. Because these blood vessels are so small, an excess of sugar in the blood that flows through them can also cause a blockage. If they are blocked, your body will respond by trying to grow new blood vessels. However, these new passages do not develop as well as the old ones, and can leak easily. As the disease gets worse, it can cause vision loss and other serious complications.
Types of Diabetic Retinopathy
Diabetic retinopathy is categorized into two main types.
Non-Proliferative Diabetic Retinopathy (NPDR)
This is the early stage of diabetic retinopathy. Here someone with the condition might not even notice the symptoms. In NPDR, the blood vessels in the retina are weakened. The earliest sign of the condition is tiny abnormal bulges in these blood vessels, called microaneurysms. When a doctor looks at your eyes, that is what they are looking for first to diagnose you with diabetic retinopathy. NPDR is classified into three levels:
- Mild NPDR: In this stage, there will be a few microaneurysms. There are occasional leaks, called hemorrhages, but people with mild NPDR often do not have their vision affected or need treatment.
- Moderate NPDR: In NPDR, the damage to blood vessels is more widespread and there is more leaking. Two additional symptoms can show up here, cotton wool spots and hard exudates. Cotton wool spots are small lesions that look like clouds. Hard exudates are yellow flecks in the eye that happen when protein and fat starts to leak out and build up.
- Severe NPDR: Severe NPDR is diagnosed by following the "4-2-1" rule. The eye itself is made up of four quadrants, like the heart is made of four chambers. For severe NPDR, doctors are looking for severe hemorrhages in all four quadrants of the eye, venous bleeding in at least two, and intraretinal microvascular abnormalities (IrMA) in at least one. Hemorrhages are the blood vessels leaking. Venous bleeding is when blood vessels no longer look parallel and start to look more like sausage links. IrMA is when the blood vessels start to stretch out or grow where they are not supposed to. At this stage, people have a 52% chance of developing PDR within 1 year.
Proliferative Diabetic Retinopathy (PDR)
This is the most advanced form of diabetic retinopathy. In PDR, damage to blood vessels has deprived the eye of oxygen. This causes new, abnormal blood vessels to start to grow in the retina and even into the vitreous, which is the fluid that fills the back of the eye. These new vessels are fragile and can leak easily. Over time they can even form scar tissue. PDR can lead to even more serious complications!
- Retina Detachment: Scar tissue can pull on the retina, causing it to detach. This is called tractional retinal detachment, and can even lead to tears or holes.
- Neovascular Glaucoma: Neovascular glaucoma is when new blood vessels in the eye stop fluid from draining, causing an increase in pressure. PDR is one of the leading causes of neovascular glaucoma.
Diabetic Macular Edema (DME) and PDR
Diabetic macular edema (DME) is a complication of diabetic retinopathy that can happen at any stage of the disease. Of note, Diabetic macular edema (DME) can develop separately from proliferative diabetic retinopathy (PDR) and is not always associated with PDR in patients with type 1 or type 2 diabetes. However, DME is often associated with PDR. DME happens when fluid from damaged blood vessels build up in the macula, the central part of the retina. This swelling can lead to blurriness and central vision loss. This makes simple tasks like reading and driving difficult.
Diabetic retinopathy, including PDR and DME, is a leading cause of vision loss in people aged 25-74 worldwide. By 2030, an estimated 191 million people globally will have diabetic retinopathy! 56.3 million of these are expected to be at vision-threatening stages. One of the biggest concerns with diabetic retinopathy is that it often progresses without symptoms in its early stages. If you have diabetes, you should get regular comprehensive eye exams to find and treat it early!
Diagnosis and Treatment
The best way to catch diabetic retinopathy is with a comprehensive eye exam. This can consist of:
- Dilated eye exam: Here, doctors will look at the retina to find abnormalities (like those microaneurysms).
- Optical coherence tomography (OCT): This test is done to find swelling in the macula.
- Fluorescein angiography: This test will assess blood flow in the retina.
If diagnosed with either PDR or DME, there are a few treatments a doctor may recommend! For both conditions, anti-VEGF injections may help depending on the exact condition and location of the disease. Medicines like bevacizumab, ranibizumab, and aflibercept help reduce abnormal blood vessel growth and fluid leakage. A procedure called panretinal photocoagulation (PRP) laser therapy targets areas of the retina to reduce abnormal blood vessel growth. This helps to prevent bleeding and retinal detachment in PDR. In cases of severe PDR, where there is extensive bleeding or retinal detachment, vitrectomy surgery may be needed to remove the vitreous gel and scar tissue inside the eye.
The best way to prevent PDR and DME is to manage your underlying diabetes. Your goal, working alongside your doctor, should be to keep your blood sugar, blood pressure and cholesterol levels in their target ranges. Make sure you are getting comprehensive regular eye exams, at least once a year or as recommended! PDR is a serious condition, not to be taken lightly. But you have the tools and resources to take control of your health and ensure you preserve your vision and prevent long-term complications.
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