Diabetic Retinopathy: Causes, Prevention, and Treatment

From diatribe.org

Key takeaways: 

• Screening for diabetic retinopathy is important as many people do not show symptoms until the disease has progressed. 
• New technology, like artificial intelligence, may make screening for diabetic retinopathy easier. 
• Treatment for diabetic retinopathy may involve eye injections, laser therapy, or surgery to remove leaking fluid. 

Diabetic retinopathy is the most common eye disease among people with diabetes and the main cause of blindness in American adults. According to the National Eye Institute, more than half of people with diabetes will develop retinopathy over time. 

Often, the symptoms of DR do not appear until it has progressed to the point of severe vision loss. Read on for valuable advice on screening, how to prevent retinopathy, and a glimpse into current and future treatments. 

What is diabetic retinopathy?

Diabetic retinopathy is a diabetes complication that occurs when blood vessels in the retina of the eye are damaged or swollen, or begin to grow irregularly. It has four stages: mild, moderate, severe, and proliferative retinopathy. 

At first, diabetic retinopathy may cause no symptoms. If left untreated, however, it can cause severe vision loss or even blindness.
A retinopathy diagnosis may mean the presence of other diabetes-related complications occurring elsewhere in the body. For instance, a 2021 study found that people with diabetic retinopathy are twice as likely to develop heart disease compared to people without it. Likewise, diabetic retinopathy is also linked to a higher risk of chronic kidney disease. 

What causes diabetic retinopathy?   

Anyone with type 1 or type 2 diabetes is at risk of developing diabetic retinopathy, which is caused by high blood sugar over time – typically, many years. Chronic high blood sugar levels can lead to damage and blockage of the tiny blood vessels in the retina, diminishing blood supply. 

When this blood supply is cut off, the eye develops new blood vessels. However, these new blood vessels don’t develop properly and can easily leak fluid, causing vision loss. The longer a person lives with diabetes, the more likely he or she is to develop retinopathy.

How to prevent diabetic retinopathy

To answer this question, we spoke to Dr. Ivan Suñer, an ophthalmologist and retinal surgeon at Retina Associates of Florida, and Mike Ellis, a person who was diagnosed with diabetic retinopathy at age 63.

Suñer emphasized that monitoring and controlling blood sugar, blood pressure, and cholesterol are key steps to preventing diabetic retinopathy. A1C levels also have a direct relationship with the risk of developing diabetic retinopathy – maintaining an A1C of less than 6.5% is associated with a decreased risk, according to the American Diabetes Association.

Regular exercise also decreases the risk of diabetic retinopathy and other long-term complications. Suñer also pointed out that limited research suggests smoking cigarettes increases the risk for diabetic retinopathy if you have type 1 – but not type 2 – diabetes.

The most critical piece of information Suñer shared was that people with all stages of diabetic retinopathy often have no symptoms until they are at extremely high risk for vision loss. Thus, he strongly emphasized the importance of regular screening with a comprehensive eye examination.

Our conversation with Ellis taught us the same lesson. Ellis hadn’t seen a doctor in years when he started losing his vision, and only when he started having trouble doing the things he loved, including fly fishing and working on cars, did he see a doctor. 

His physician diagnosed him with type 2 diabetes and diabetic retinopathy at the same appointment. He had no reason to believe that he had diabetes – while a majority of people with type 2 diabetes are overweight, he had been fit and active his entire life. Thus, the number one piece of advice he wanted to share was to see a doctor regularly and get screened.

Screening for diabetic retinopathy 

Because early detection of diabetic retinopathy is key to preventing vision loss, people should be screened through a dilated eye exam by an ophthalmologist or optometrist. An eye exam performed by a primary care doctor (without eye dilation) does not replace a full exam done by an eye doctor. 

The ADA recommends that anyone with type 1 diabetes receive an initial dilated eye examination within five years of being diagnosed with diabetes. Anyone newly diagnosed with type 2 diabetes should receive a dilated eye exam by a specialist immediately after diagnosis. 

However, because there are a limited number of eye specialists in the U.S., screenings are not always easy for everyone with diabetes to do as directed by the ADA. 

Historically, the images taken during screening were interpreted by an ophthalmologist. However, this might change in the future with the development of artificial intelligence. Eyenuk’s EyeArt AI Screening System gained FDA approval in 2023 and AEYE Health’s AEYE-DS received FDA approval in 2024; both systems provide AI-based detection of diabetic retinopathy. AI-based screening could be especially useful for people who live in rural areas or places with limited access to eye doctors. 

Research suggests that a considerable proportion of people with type 2 diabetes have some level of retinopathy at the time of diagnosis – up to 16%, according to a 2023 study. The recommended frequency of screenings depends on the stage of retinopathy. People with mild retinopathy may need to be screened once a year; people with more severe disease may need eye exams on a more frequent basis. 

The silver lining of Ellis’ diagnosis was that it served as a “wake-up call” to his younger siblings. After he was diagnosed with diabetic retinopathy, he encouraged them all to get tested for diabetes. It turned out that they all had blood sugars in the prediabetes range. This information gave them the opportunity to proactively change their lifestyles, potentially preventing the onset of type 2 diabetes and its complications.

How is diabetic retinopathy treated?

Treatment options depend largely on the severity of the disease. Mild or moderate retinopathy may not require immediate treatment; managing blood sugar can usually slow the progression of the condition. It’s also important to manage blood pressure and cholesterol levels. 

For people with more advanced stage diabetic retinopathy, treatment options include:

1. Injections

Anti-VEGF drugs, such as Lucentis and Eylea, can help slow down or reverse early-stage disease. They are given by a healthcare provider as a monthly eye injection for people who do not yet need surgery. Anti-VEGF drugs block a protein that causes damage to blood vessels in the eye. According to Suñer, as many as 40% of people with diabetic retinopathy see significant improvements after using these drugs.

Newer and more powerful medications, like higher-dose Eylea, have the potential to reduce the frequency of injections. Other medicines, called corticosteroids, can help reduce swelling and inflammation. 

2. Laser treatment

For people who do not see improvement after injections, focal laser treatment allows doctors to shrink abnormal blood vessels through a laser procedure. According to the National Eye Institute, focal laser treatments can reduce the risk of vision loss by 50%.

3. Eye surgery

If blood vessels in the eye have significant bleeding, a surgical procedure called a vitrectomy may be performed. In this procedure, vitreous gel containing leaked blood is removed from the eye as well as any scar tissue. Laser treatment is also performed to help prevent the recurrence of new blood vessels and bleeding. 

When Ellis was diagnosed, he started receiving Lucentis injections as a treatment. Fortunately, these injections helped him regain his vision within a year. He has regained the ability to do all the activities he loves again, including fishing and tutoring children at his local church. According to his doctor, he likely would have lost his vision completely had he not caught the symptoms when he did (and if this treatment hadn’t been available to him). Although he said it’s certainly not comfortable to get injections in his eyeballs every month, it’s a small price to pay for maintaining his vision. 

Surgical interventions like focal laser treatment and vitrectomy often slow or stop the progression of diabetic retinopathy, but they are not cures. Regular eye exams are thus necessary to continue monitoring diabetic retinopathy.

The future of diabetic retinopathy treatment

Along with advancements in screening for retinopathy, treatments are ever-evolving as well. Here’s a look at what may be coming in the future.

New medications

Researchers are investigating medications such as fenofibrate, an oral drug traditionally used to lower cholesterol. For instance, a 2022 study of nearly 150,000 participants found that using fenofibrate was linked to a lower risk of proliferative retinopathy and vision-threatening retinopathy. Additional research suggests that fenofibrate may slow the progression of the disease. 

Implant devices

Researchers are investigating eye implants that release a drug (e.g. Lucentis) over a prolonged period of time, instead of regular, frequent injections. With eye implants, patients would need to refill the device less frequently (i.e., potentially every six or eight months). Susvimo, an eye implant, has been approved for patients who have wet age-related macular degeneration. Clinical trials are currently underway to investigate Susvimo in people with diabetic retinopathy without diabetic macular edema. 

Combination therapies

Other researchers are investigating the effectiveness of combining multiple therapies for diabetic retinopathy earlier in treatment. For instance, laser therapy at the start of treatment, rather than beginning with injections and then performing surgery later on. While this research is in its early stages, Suñer has seen that combination therapy can lead to better outcomes and fewer treatments down the road.

The bottom line

Being screened for diabetic retinopathy is the most important action that people with diabetes can take to prevent severe vision loss and blindness. 

Improving blood sugar levels by getting regular exercise and eating a nutritious diet can prevent diabetic retinopathy and even reverse it in its early stages. However, since symptoms may not appear until the disease is more severe, the only way to know if you are at risk is to get regular eye screenings from your eye doctor. 

https://diatribe.org/diabetes-complications/diabetic-retinopathy-causes-prevention-and-treatment