From yalemedicine.org
A leading cause of blindness, this condition can develop without symptoms, making preventive steps and eye exams imperative
If you have diabetes, it’s not only your blood sugar levels you need to pay close attention to, but also your vision.
Over time, high blood sugar levels can damage the delicate blood vessels in your eyes, causing a condition called diabetic retinopathy—a leading cause of blindness both globally and in the United States.
The lifetime risk of diabetic retinopathy is striking: about 50-60% for people with type 2 diabetes, and more than 90% for those with type 1 diabetes.
The good news, says Yale Medicine ophthalmologist Kristen Nwanyanwu, MD, MBA, is that blindness from diabetic retinopathy is largely preventable.
“The first treatments for diabetic retinopathy were identified more than 40 years ago and they’ve only gotten better,” Dr. Nwanyanwu says. “We now have options ranging from laser treatments to medications injected into the eye. The challenge is that the disease can progress quietly, so it’s crucial that people see their medical provider at the right time.”
Because damage to the eye from diabetic retinopathy often occurs before any vision problems appear, annual eye exams are important.
“If you have diabetes, you need to have your eyes screened,” Dr. Nwanyanwu emphasizes. “Even if you are seeing well, you can still have damage from diabetes in your eyes.”
What is diabetic retinopathy?
Diabetic retinopathy develops when chronically high blood sugar damages the tiny blood vessels in the retina—the light-sensitive layer at the back of the eye that helps you see clearly.
Type 1 diabetes usually occurs when the immune system destroys the cells that produce insulin, leaving the body with very little or none. Type 2 diabetes generally happens when the body doesn’t respond well to insulin (insulin resistance) or doesn’t make enough insulin, often due to a mix of genetic and lifestyle factors. In both conditions, persistently high blood sugar can harm blood vessels throughout the body, including in the eyes.
“When the retina’s blood vessels are damaged, they lose their protective cells, which makes them prone to breaking and bleeding,” Dr. Nwanyanwu explains. As the disease advances and blood flow decreases, the eye tries to make new blood vessels. “But the only time you want to make new vessels in the eye is in utero—otherwise, new vessels in the eye are harmful. They’re weak, they bleed easily, and cause blurred vision.”
“In the late stages of diabetic retinopathy, abnormal blood vessels can cause vitreous haemorrhage, which is bleeding in the eye cavity, or even retinal detachment,” she says. “Both of those can lead to blindness.”
Who is most at risk for diabetic retinopathy?
Diabetic retinopathy can affect anyone with type 1 or type 2 diabetes. In 2021, an estimated 9.6 million people in the U.S.—about 26% of those with diabetes—were living with the condition. It is the leading cause of vision loss in working-age people in the country.
People with diabetes who have had chronically elevated blood sugar levels, a stroke, a heart attack, an amputation, kidney failure, or who are on dialysis are all at higher risk of eye disease because of their advanced disease, Dr. Nwanyanwu says.
Those with type 1 diabetes should be screened for diabetic retinopathy within five years of diagnosis; those with type 2 should be screened as soon as they are diagnosed.
“It can take time for damage to occur with type 1 diabetes, which is usually diagnosed quickly, but with type 2 diabetes, people may have had undetected high blood sugar levels for years before being diagnosed, and damage might have already happened,” she says.
How is diabetic retinopathy prevented?
The key to preventing diabetic retinopathy is maintaining healthy blood sugar levels and scheduling regular eye exams. That’s because while the initial damage is happening, it doesn’t cause noticeable vision changes and people continue to see fine—making it easy to overlook.
“If you are seeing perfectly fine, your eyes might not feel like a priority when you already have a list of health care maintenance things to do because of your diabetes,” Dr. Nwanyanwu says. “Add challenges like busy schedules, parenting demands, food or housing insecurity, or financial stress, and it’s easy to see why eye exams sometimes get skipped. But getting a regular, comprehensive eye exam should be at the top of the list.”
How is diabetic retinopathy diagnosed?
Doctors have more tools than ever for detecting diabetic retinopathy. A dilated eye exam remains the gold standard, but new approaches include tele-ophthalmology (where images of the eye are taken with specialized cameras and sent to specialists for review) and artificial intelligence systems designed to flag signs of diabetic retinopathy.
During an eye exam, an eye doctor can look at the retina for signs of damage, which can include microaneurysms (small bulges in the vessels), leaking blood, and neovascularization (growth of new, fragile blood vessels that bleed easily). Additionally, doctors may see signs of swelling, called edema, in the macula, which is at the centre of the retina and is responsible for detailed vision.
How is diabetic retinopathy treated?
Fortunately, diabetic retinopathy is treatable and the outlook is encouraging. “We do a really good job of treating it and we save vision every day,” Dr. Nwanyanwu says.
First and foremost, anyone with diabetic retinopathy should work with their primary care physician or endocrinologist to manage their blood sugar levels. In some cases, better blood sugar control can reverse early diabetic retinopathy, she says.
“Because of that, we don’t start using our treatment tools until more advanced stages,” she says. And when treatment is needed, it can include medication injections into the eye that can reduce swelling in the retina and help shrink abnormal blood vessels. These are given monthly at first and then less frequently over time.
Laser treatments are also used to change the environment in the eye and stop abnormal blood vessels from growing. Laser treatments are more permanent than injections and are often used in more advanced stages of the disease.
While the treatments may sound uncomfortable, Dr. Nwanyanwu reassures patients that they are well tolerated and highly effective.
What’s the future look like for diabetic retinopathy?
Diabetes rates continue to climb globally, but advances in treatment—including newer medications such as GLP-1 agonists for obesity and diabetes—offer hope for reducing complications like diabetic retinopathy.
For now, the key is vigilance. “I don’t expect to see rates decline in the near future, but that is our ultimate goal,” says Dr. Nwanyanwu, who notes that this is the goal of Yale Medicine’s SEEN (Sight-Saving Engagement and Evaluation in New Haven) Lab, which she directs. “Every day, I wake up eager to help prevent blindness that doesn’t need to happen,” she says.
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