Proliferative Diabetic Retinopathy: Protecting Your Vision
Understanding Proliferative Diabetic Retinopathy
Proliferative diabetic retinopathy, often called PDR, is the most severe form of diabetic retinopathy. It develops when prolonged high blood sugar damages the tiny blood vessels that supply the retina. Over time, these damaged vessels become blocked or close off, cutting the retina's blood supply.
When the retina does not receive enough blood and oxygen, it releases chemical signals called growth factors. These growth factors trigger the formation of new, abnormal blood vessels on the retina's surface. This process is called neovascularization. Unlike healthy blood vessels, these new vessels are fragile and prone to bleeding.
Chronic high blood sugar leads to dysfunction in the retina's blood vessels through inflammation and oxidative stress. This damages the cells that support and line the tiny capillaries. As oxygen supply drops, the retina produces a protein called vascular endothelial growth factor (VEGF). VEGF drives the growth of abnormal new blood vessels.
These new blood vessels grow into the vitreous (the clear gel that fills the inside of the eye). As they grow, they bring along scar tissue that forms a firm attachment between the retina and the vitreous. When this scar tissue contracts, it can pull on the fragile vessels and cause bleeding inside the eye. This bleeding is known as vitreous hemorrhage. In more severe cases, the pulling force can detach the retina from the back wall of the eye.
Several serious complications can result from proliferative diabetic retinopathy:
- Vitreous hemorrhage: Bleeding from fragile new vessels fills the vitreous, blocking light from reaching the retina and causing sudden vision loss or floaters.
- Tractional retinal detachment: Scar tissue pulls the retina away from its normal position, which can cause severe and lasting vision loss if not treated.
- Neovascular glaucoma: Abnormal blood vessels may grow on the iris (the colored part of the eye) and clog the eye's drainage system, raising eye pressure and causing pain.
Who Is Affected and Risk Factors
Diabetic retinopathy is the most common cause of irreversible blindness in working-age Americans. A global analysis estimated that 9.60 million people were living with proliferative diabetic retinopathy (Teo et al., The Lancet Global Health, 2021). At five years following a type 2 diabetes diagnosis, approximately 1.74% of patients had developed PDR (Diabetes Care, 2021).
The Wisconsin Epidemiologic Study of Diabetic Retinopathy found that after 20 years with diabetes, 99% of patients with type 1 diabetes and 60% of patients with type 2 diabetes showed some degree of retinopathy (AAO EyeWiki). PDR is rare in the first decade after a type 1 diabetes diagnosis but rises to 14 to 17% by 15 years.
The length of time a person has lived with diabetes is one of the strongest risk factors for developing PDR. After 5 years, about 25% of people with type 1 diabetes will have some retinopathy. After 10 years, nearly 60% will be affected. After 15 years, that number rises to 80% (AAO EyeWiki). The risk of progressing to the proliferative stage climbs steadily with each additional year.
Poorly controlled blood sugar significantly increases the risk of PDR. Higher blood sugar levels, longer diabetes duration, and more advanced retinopathy at diagnosis are all linked to a greater chance of developing proliferative disease (WESDR). In younger patients, higher blood pressure at baseline is also linked to increased risk.
Other factors that may raise risk include:
- High blood pressure (hypertension)
- High cholesterol
- Pregnancy in women with pre-existing diabetes
- Kidney disease related to diabetes
- Smoking
Signs and Symptoms
One of the most concerning aspects of diabetic retinopathy is that it can progress for years without causing noticeable symptoms. Many people do not realize their retinas have been damaged until the disease reaches an advanced stage. This is why regular eye exams are critical for anyone living with diabetes.
As proliferative diabetic retinopathy progresses, symptoms may appear suddenly or gradually. Common warning signs include:
- New floaters, which appear as spots or dark strings drifting across the field of vision
- Blurred or fluctuating vision
- Dark or empty areas in the visual field
- Difficulty seeing at night
- Sudden, significant vision loss
New floaters caused by vitreous hemorrhage are one of the most common first signs of PDR. A sudden increase in floaters, flashes of light, a shadow or curtain across the vision, or sudden vision loss in one eye requires immediate evaluation. See a retina specialist or go to the emergency room right away if you experience any of these symptoms.
Diagnosis and Testing
A comprehensive dilated eye exam is the foundation of diagnosing diabetic retinopathy. During this exam, drops are placed in the eyes to widen the pupils. This allows a retina specialist to examine the retina in detail. The specialist looks for damaged blood vessels, abnormal new vessel growth, bleeding, swelling, and scar tissue.
Several advanced imaging tools help retina specialists evaluate the extent of disease and guide treatment:
- Fluorescein angiography: A special dye is injected into a vein in the arm, and photographs are taken as the dye travels through the retinal blood vessels. This test reveals areas of poor blood flow and abnormal new vessel growth.
- Optical coherence tomography (OCT): This non-invasive scan creates detailed cross-sectional images of the retina. It helps detect swelling in the macula and can show areas of traction.
- OCT angiography (OCTA): This newer imaging method maps retinal blood vessel structure without injected dye, helping identify neovascularization.
People diagnosed with any stage of diabetic retinopathy need ongoing monitoring. A retina specialist will determine how often follow-up visits are needed based on severity. Patients with PDR typically require frequent visits to check for new bleeding, worsening traction, or the need for additional treatment.
Treatment Options
Anti-VEGF medications are now a primary treatment for proliferative diabetic retinopathy. These drugs block vascular endothelial growth factor, the protein that drives abnormal blood vessel growth and leakage. They are delivered as intravitreal injections (injections directly into the eye).
Common anti-VEGF medications used in PDR include Eylea (aflibercept), Lucentis (ranibizumab), Avastin (bevacizumab), and Vabysmo (faricimab). Avastin is FDA-approved for cancer treatment and is used off-label for eye conditions. These injections may be needed every 4 to 8 weeks initially. The CLARITY study showed that aflibercept was superior to laser in improving visual acuity at one year (CLARITY Trial, The Lancet, 2017). Protocol S found that ranibizumab produced visual results at least as good as laser through two years (DRCR Retina Network, 2015).
Panretinal photocoagulation, also known as PRP or scatter laser treatment, has been a standard treatment for PDR for decades. During this procedure, a retina specialist applies hundreds to thousands of tiny laser burns to the peripheral retina. This reduces the retina's demand for oxygen and decreases the signals that drive abnormal vessel growth.
PRP does not improve vision. Its goal is to prevent further vision loss by stabilizing or shrinking the abnormal new blood vessels. Side effects may include reduced peripheral (side) vision, decreased night vision, and mild changes in color perception. PRP is sometimes combined with anti-VEGF injections for more comprehensive treatment.
In some cases, particularly when diabetic macular edema (swelling in the central retina) accompanies PDR, steroid injections may be used. Options include triamcinolone acetonide and Ozurdex (dexamethasone implant), a small sustained-release device placed inside the eye. These may be considered when the eye does not respond well to anti-VEGF therapy.
Vitrectomy (a surgery to remove the vitreous gel from inside the eye) may be necessary in advanced cases of PDR. A retina specialist may recommend vitrectomy when a vitreous hemorrhage does not clear on its own, or when scar tissue causes a tractional retinal detachment. During vitrectomy, the surgeon removes the blood-filled vitreous and replaces it with a clear solution. Laser treatment is often applied during the surgery. In some cases, a gas bubble or silicone oil is placed inside the eye to hold the retina in place.
Treatment patterns for PDR have shifted significantly in recent years. An IRIS Registry analysis found that intravitreal injections surpassed PRP as the more common initial treatment for newly diagnosed PDR between 2013 and 2017 (IRIS Registry, JAMA Ophthalmology). Avastin (bevacizumab), used off-label, accounted for more than two-thirds of those injections. Eylea HD (high-dose aflibercept) has also received FDA approval for extended dosing intervals, which may reduce the number of office visits some patients need.
What to Expect
Anti-VEGF injections are performed in a retina specialist's office. The eye is numbed with anesthetic drops, and the surface is cleaned with an antiseptic solution. A very thin needle is used to inject the medication into the vitreous cavity. The procedure takes only a few minutes. Patients may feel pressure or mild discomfort during the injection. Temporary side effects can include redness, floaters, and a gritty sensation.
Panretinal photocoagulation is typically performed in the office. The procedure may be done in one or more sessions. Patients may notice some discomfort during treatment. Afterward, vision may be blurry for a day or two. Over time, some patients notice mild changes in peripheral or night vision due to the laser scars. These trade-offs are generally considered acceptable to prevent the more severe vision loss that PDR can cause.
Vitrectomy is performed in an operating room, usually under local anesthesia. Recovery time varies depending on the complexity of the surgery. If a gas bubble is placed in the eye, the patient may need to maintain a specific head position for days or weeks. Vision improvement after vitrectomy is gradual and can take weeks to months. The retina specialist will provide detailed recovery instructions and schedule follow-up visits.
Living With Proliferative Diabetic Retinopathy
Controlling blood sugar is the single most important step in slowing the progression of diabetic retinopathy. Work closely with your diabetes care team to keep hemoglobin A1c levels within the target range recommended for you. Managing blood pressure and cholesterol levels also plays a significant role in protecting retinal health.
Regular follow-up visits with a retina specialist are essential for anyone diagnosed with PDR. Even after successful treatment, new abnormal blood vessels can develop or existing ones can start bleeding again. Ongoing monitoring allows problems to be detected and treated before they cause additional vision loss. Most patients with PDR will need long-term follow-up care.
Living with a vision-threatening condition can be stressful. It is normal to feel anxious about the possibility of vision loss or overwhelmed by frequent treatments. Support from family, diabetes educators, and low-vision rehabilitation specialists can help patients adapt. If vision loss has occurred, low-vision aids and training programs may help with daily tasks.
When to See a Retina Specialist
All people with diabetes should have a comprehensive dilated eye exam at least once a year, or more often if recommended. Early stages of diabetic retinopathy typically produce no symptoms, so screening is the only way to detect the disease before significant damage occurs. Catching retinopathy early gives a retina specialist the best opportunity to preserve vision.
Certain symptoms signal a possible emergency and require prompt evaluation. See a retina specialist or go to the emergency room immediately if you experience a sudden increase in floaters, flashes of light, a dark curtain or shadow moving across your vision, or sudden vision loss in one eye. These symptoms may indicate vitreous hemorrhage or retinal detachment, both of which need urgent treatment to protect remaining vision.
Questions and Answers
PDR cannot be reversed once it has developed. Treatments such as anti-VEGF injections, laser therapy, and vitrectomy aim to stop the disease from getting worse and to prevent further vision loss. In some cases, treatment can lead to improvements in vision, particularly when bleeding clears or swelling is reduced. However, retinal damage that has already occurred may be lasting. This is why early detection and treatment are so important.
The number of injections varies from person to person. Many patients receive a series of injections over the first few months, with ongoing treatments as needed. Some patients require injections for months or years to keep the disease under control. A retina specialist will monitor the response and adjust the schedule accordingly. Newer medications and extended dosing options may help reduce the total number of injections over time.
Panretinal photocoagulation can cause some discomfort during the procedure. Most patients describe it as a mild aching or stinging sensation. Numbing drops are applied before treatment to reduce discomfort. The level of sensation varies depending on the number of laser spots applied. Any discomfort during the procedure is temporary and typically fades shortly after the session.
Not all people with PDR lose their vision. With prompt treatment and careful management of diabetes, many patients maintain useful vision for years. However, PDR is a serious condition, and the risk of significant vision loss is real, especially if the disease is left untreated. Controlling blood sugar, keeping all recommended appointments, and following the treatment plan from a retina specialist are the best ways to protect your sight.
Physical activity is generally beneficial for overall diabetes management. However, certain types of intense exercise may raise the risk of bleeding inside the eye for people with active PDR. Activities that involve heavy straining or sudden jarring movements may need to be modified. Discuss exercise plans with both your diabetes care team and your retina specialist for guidance based on your current eye health.