From High Blood Sugar to Vision Loss With DME
Damage to the tiny vessels in your retina can permanently affect your eyesight. Here's how to prevent that from happening.
If you’ve been diagnosed with diabetes, you know how complicated it can be to manage this systemic condition that can affect every organ and tissue in your body over time.
But if there’s one thing you may not be thinking about doing—but should—it’s getting an eye exam—as in, ASAP. “The majority of people with diabetes will eventually develop diabetic retinopathy, which is damage to the tiny blood vessels in the eye’s retina,” says Lloyd P. Aiello, M.D., director of the Beetham Eye Institute at the Joslin Diabetes Center in Boston and professor of ophthalmology at Harvard Medical School. “About one-third of those people will go on to develop diabetic macular edema, or DME, which occurs when fluid from those damaged blood vessels leaks into the macula in the center of the retina.” Your chances of developing diabetic retinopathy or DME is not a matter of luck, but directly related to long term blood sugar control.
That’s a real problem because the macula is a very important part of vision: It helps you see objects directly ahead, as well as fine detail, color, and faraway objects. If anything affects the macula, it almost always will affect your eyesight. While most eye diseases like cataracts and macular degeneration develop in older people, DME can occur much earlier.
“DME is the most common blinding eye disease in people of working age, between their 30s and 50s,” explains Timothy Murray, M.D., an ophthalmologist in Miami and immediate past president of the American Society of Retina Specialists. That sounds pretty scary, but there is good news, too: “DME is very treatable when detected early,” he adds. “We can prevent progression and improve existing disease.”
An Inside Look
When you have diabetes, your body doesn’t make enough insulin or becomes resistant to insulin. As a result, the sugar hangs around in your bloodstream, which eventually damages blood vessels throughout your body by decreasing their elasticity and causing them to narrow, compromising blood flow and reducing oxygen levels in the blood.
In the retina, this decreased blood flow causes the pericytes—cells that wrap around and act as a sealant for the blood vessels—to retract and die off, says Dr. Murray. The blood vessels then develop balloon-like bulges inside, essentially mini aneurysms. This swelling increases the surface area of the blood vessel, so it’s thinner and not as water-tight. As a result, fluid, blood, and lipid can leak out of the vessels and into the retina at first. If the condition progresses to affect the macula, it is called diabetic macular edema, or DME, the leaking extends into the macula, and the excess fluid short-circuits the messages being sent to the brain so that the images you see are distorted.
“It may be 10 or 20 years into diabetes before we see DME, but it can occur in the first year as well,” says Howard R. Krauss, M.D., neuro-ophthalmologist and clinical professor of ophthalmology and neurosurgery at John Wayne Cancer Institute in Santa Monica, CA.
The most severe stage is known as proliferative diabetic retinopathy (PDR). At this stage, the damaged blood vessels close off, depriving the retina of oxygen. If enough of the retina is not getting blood supply, new but abnormal blood vessels can grow. Because these new blood vessels are very fragile, they may leak even more or bleed inside the eye, known as vitreous hemorrhage. Scar tissue from the growth of the new blood vessels may also cause the retina to detach. Eventually, complete vision loss can occur.
Seeing an Ophthalmologist
The standard advice for most ailments (including many eye problems, serious or not) is to see your doctor at the first sign of symptoms. That’s not the case with DME: You want to get to an eye doctor as soon as you’re diagnosed with diabetes so you can be monitored at least annually for both diabetic retinopathy and DME before you ever have any symptoms. “There’s a magic window when vision starts to shift from 20/20 to about 20/30 or 20/40 when we need to start treatment,” notes Dr. Aiello. At this stage, most people probably won’t have noticed that their vision is changing yet, but they may still have bad edema. Your eye doctor can use retinal photography and other diagnostic eye tests to monitor changes to the retina before your vision is affected, Dr. Krauss explains.
It’s also important which type of eye doctor you see. A doctor of optometry (D.O.) is like a primary care physician for your eyes—this physician. An ophthalmologist, however, is a medical doctor who specializes in the eye, performs eye surgery, and treats more serious eye diseases like diabetic retinopathy and DME. So seek out an appointment with the latter. An important part of the exam is being dilated with drops in the office. These drops enlarge your pupils so your ophthalmologist can look inside your eyes and directly visualize your retina. You may be blurry for several hours after a dilated eye exam. Some ophthalmologists also have additional training in diseases and surgery of the retina and vitreous body of the eye. They're known as retina specialists or vitreoretinal surgeons, and are highly skilled in treating diabetic eye disease.
In addition to frequent monitoring, you’ll also want to be on the lookout for any of the following symptoms of DME:
Blurry, wavy, or distorted vision
Floaters—specks, strings, or cobwebs—in your vision
Difficulty reading at any distance
Seeing colors as washed out or faded
Blind or dark areas or spots in your field of vision
Preventing DME With a Healthy Lifestyle
Keeping your blood sugar levels under control is one of the most important things you can do to prevent and slow the progression of diabetic retinopathy and DME. “The landmark Diabetes Control and Complications Trial proved that people with diabetes who kept their blood glucose levels as close to normal as possible with intensive treatment could slow the development of eye disease as well as other complications,” explains Dr. Murray. Having high blood pressure (HBP) and high cholesterol levels also add to your risk of DME, so controlling those with medication and lifestyle changes like losing weight, exercising, and quitting smoking are also helpful. “It’s totally within your power,” says Dr. Krauss. “I have many patients who never develop diabetic retinopathy or DME, as well as other diabetic complications.”
Treating DME With Injections and Steroids
The first line of defense is anti-VEGF medications, which are given as eye injections. VEGF stands for vascular endothelial growth factor, a naturally occurring protein that causes the body to create new blood vessels when under duress and also causes blood vessels to leak. “Anti-VEGF drugs act like spot welders, plugging the leakage. This prevents the formation of these problematic new vessels and can cause ones already present to resolve,” explains Dr. Aiello. Anti-VEGF treatments can slow the progression of DME and retinopathy, but may not completely reverse vision that has been lost.
Patients with more advanced DME have other options as well. Steroid treatments—in the form of pills, eye drops, injections, or implants—can be given along with anti-VEGF treatment or on their own. Steroids reduce inflammation and swelling, but can also increase your risk for glaucoma and cataracts.
Focal laser to remove fluid in the macula and panretinal laser to retinal areas no longer getting blood supply — the go-to treatments only a decade or so ago — are still used, but less frequently now. “Laser treatment can cause collateral damage to the rest of the retina,” Dr. Krauss says. “Still, this can be a good secondary tool for people who have more serious proliferative diabetic retinopathy and are at greater risk of vision loss.”
The bottom line? Things are looking up for people with diabetes who develop DME. “Anti-VEGF injections have revolutionized treatment,” says Dr. Murray. Frequent vision checkups by an ophthalmologist and aggressive treatment means many fewer people with diabetes will get DME, and those that do can be cured. DME can come back, so you’ll still need to monitored, but there’s more good news on the horizon. “Researchers are studying gene therapies that may one day allow the eye to make its own anti-VEGF proteins,” he adds. A possible advancement to definitely keep an eye on.
DME Overview: National Eye Institute. (2019). “Macular Edema.” nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/macular-edema
Retinal Damage: Developments in Ophthalmology. (2016). “Diabetic Retinopathy and Diabetic Macular Edema.” ncbi.nlm.nih.gov/pmc/articles/PMC4775164/
Diabetes Management: Diabetes Care. (2014). “The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study at 30 Years: Overview.” ncbi.nlm.nih.gov/pmc/articles/PMC3867999/
Anti-VEGF Treatment: Clinical Ophthalmology. (2017). "Anti-VEGF treatment of diabetic macular edema in clinical practice: effectiveness and patterns of use (ECHO Study Report 1)." ncbi.nlm.nih.gov/pmc/articles/PMC5328320/