Recognizing, Treating, and Preventing Diabetic Eye Disease
Though it sounds like a single condition, diabetic eye disease is actually a group of vision-related problems that can result from various factors, including chronically high blood glucose and blood pressure. Diabetes affects the entire body and, if it’s not properly managed, can lead to complications, such as damage to your blood vessels (the arteries, veins, and capillaries that the heart moves blood through) and nerves, including those in your eye. The good news is that you can lower your risk for eye problems by managing your diabetes—an important part of staying healthy head to toe—and getting regular eye exams. An eye doctor (ophthalmologist) can detect eye problems before they get too serious and can help you treat these problems early.
Retinopathy and Related Eye Problems
Diabetes can affect your eyesight in different ways. Even if you don’t have eye problems, you may notice that your vision blurs when your blood glucose is high or low but clears up once your levels are back within your target range.
But over time, diabetes can also damage the capillaries (tiny blood vessels) in the retina—a layer at the back of the eye—causing more-permanent changes to your vision. “Just like you can damage the capillaries that nourish your toes, kidneys, or heart, the tiny blood vessels that nourish the retina could be damaged by diabetes,” says Neil Bressler, MD, professor of ophthalmology and chief of the Retina Division at Johns Hopkins University School of Medicine. This is called diabetic retinopathy and causes blurred or cloudy vision or, if left untreated, complete loss of vision.
There are two major stages of diabetic retinopathy: the first is early-stage nonproliferative that can progress to the more advanced proliferative.
In nonproliferative retinopathy, small areas of swelling occur and the capillaries found in the retina begin to leak. “This [leaking] starts to shut down the capillaries, and then you get areas that don’t have adequate circulation, oxygen, and other nutrients,” says Richard Rosen, MD, director of retina services at the New York Eye and Ear Infirmary of Mount Sinai.
In proliferative retinopathy, the closed-off capillaries kick off a series of events. Because oxygen and nutrients aren’t getting to the cells in your eye, new abnormal capillaries start to form on the retina. These fragile new capillaries bleed and leak even more fluid into the eye, affecting your vision. If left unchecked they can also grow into the center of the retina responsible for central vision, called the macula, and affect your field of vision.
In either stage of retinopathy, fluid leaking from the capillaries can cause the macula to thicken or swell. The resulting condition, called macular edema, can lead to mild to severe vision loss in the center of your vision. Macular edema is the most common cause of vision loss in people with diabetes.
The breaking and bleeding of the abnormal capillaries also causes scar tissue to develop. Built-up scar tissue can tug on the retina, eventually pulling it off from the back of the eye. “[The process is] just like peeling wall paper off of a wall,” says Bressler. This can appear slowly or suddenly and is known as retinal detachment. The abnormal capillaries may also shrink, pulling on the retina and causing the same problem.
Your risk for developing diabetic retinopathy is greater if you:
- Have had diabetes for a long time. The longer you’ve had it, the higher your risk.
- Have chronically high blood glucose.
- Have high blood pressure.
- Have cholesterol problems.
- Have a family history of both diabetes and eye problems.
- Are African American or Latino.
Because the leaking capillaries reside inside your eye, you won’t be able to see any sign of a problem by looking in the mirror. That’s why regular eye exams are crucial. Though diabetic retinopathy and macular edema affect vision, they can be hard to spot early on. In fact, you can have each for some time without any symptoms at all. But if you notice any changes that last more than a few days or are not related to changes in your blood glucose, see your ophthalmologist pronto.
Nonproliferative or Proliferative Retinopathy:
- Blurred vision
- A sudden shower ofblack “floaters” in your vision (it’s really blood falling into the middle of the eye)
- Loss of vision starting from the side—thinkof it as “a dark curtain that comes from the side and starts to encroach onto thecenter of your vision as the retina detaches from the side toward the center,” says Bressler. This can appear slowly or suddenly.
- Cloudy central vision, such as when trying to read or tell time
- Seeing straight lines as if they are bent
- Trouble seeing at night
At first, macular edema may affect only one eye—and you might not notice a change in vision right away: Your brain may ignore the blurry vision in one eye, focusing on the best parts of the vision in both eyes. “Unless you cover the good eye, you might not notice the blurry vision developing,” says Bressler.
- A sudden or gradual increase in the number of floaters in your field of vision
- Light flashes in the eye
- Loss of vision starting from the side
When to Get Checked
Often diabetic retinopathy has no symptoms, but with regular screenings, you can catch and treat problems before vision loss occurs. If you have noticed a change in vision, don’t wait until your next appointment to tell your eye doctor, says Raj Maturi, MD, associate professor of ophthalmology at Indiana University School of Medicine and partner at the Midwest Eye Institute in Indianapolis. Visit your ophthalmologist right away. The American Diabetes Association’s 2017 Standards of Medical Care in Diabetes recommends:
- Adults with type 1 have a dilated eye exam within five years of their diabetes diagnosis.
- Adults with type 2 have a dilated eye exam at the time of their diabetes diagnosis.
- People with type 1 and type 2have annual dilated eye exams. If there is no evidence of retinopathy for one or more annual exams and blood glucose is well managed, doctors may recommend eye exams every one to two years. If there is evidence of diabetic retinopathy, exams should be repeated at least yearly. If retinopathy is progressing or threatening vision, then exams should be more frequent.
- Kids who’ve had type 1 diabetes for three to five years get a comprehensive eye exam at age 10 or after puberty has begun, whichever is earlier.
- Women with diabetes receive an eye exam before becoming pregnant or in the first trimester and then every trimester. Talk to your eye doctor about how often you should have exams during the first year after giving birth. Pregnancy can hasten the start or progression of diabetic retinopathy.
Tests and Exams
Comprehensive Eye Exam
An eye exam is pretty straightforward. Here’s what to expect: Your eye doctor will first check whether there is a change in your eyeglass or contact lens prescription. (People with macular edema, diabetic retinopathy, and other eye diseases can still wear contacts, says Maturi.)
Next, the doctor will drip a few drops in your eyes to dilate the pupils. Twenty to 30 minutes later, your eyes will be fully dilated and, using special lenses and lights, the doctor will be able to look into your eye and see your retina and macula in great detail. This is used to find signs of retinopathy, macular edema, and retinal detachment.
If you’re in an area that doesn’t have access to qualified eye doctors, you may have a high-quality photograph taken of the inside of your eye. This image is sent to an eye care provider who’s trained in looking for signs of damage in photographs, which isn’t as easy as finding problems during an eye exam. You will still need to see an ophthalmologist if the images aren’t clear enough to review or if there’s evidence of damage to your eye.
A fluorescein angiogram shows your ophthalmologist if, and how much, your blood vessels are leaking. During the test, a dye is injected into the arm. Within 45 seconds, the dye reaches the back of the eye. Just as blood leaks from the weak blood vessels, so does the dye. “[It] shows exactly where the abnormal blood vessels are located,” Maturi says. Pictures are taken to document the results.
Optical Coherence Tomography Angiography
In the last two years, a new form of imaging, called optical coherence tomography angiography, has emerged. It’s not yet widely available but can detect diabetic retinopathy long before the capillaries start leaking blood and fluid.
This new technology allows your eye doctor to see into the retina to examine blood flow, swelling, and whether your eye is losing capillaries, Rosen says. Your ophthalmologist can also measure how the disease has progressed at each visit. “We can tell if [the person] is losing capillaries—and how fast,” says Rosen.
Optical Coherence Tomography
For signs of macular edema, the eye doctor looks directly at the macula—but that may not be enough for a diagnosis. Your doctor may need to use optical coherence tomography, a laser-based scan of the back of the eye that measures the retina to detect macular edema. Even though the retina is wafer thin, the test is able to measure retinal thickening as slight as a thousandth of a millimeter, says Bressler.
Your doctor will also look for cataracts (clouding of the lensat the front of the eye), glaucoma (high pressure in the eye), and retinal vein occlusion (a blockage of blood flow in one of the retinal veins), all of which are more common in people with diabetes.
Over the past decade, new research and significant improvements in technology have aided our ability to diagnose and treat diabetic retinopathy, and advances in medications are giving people with diabetes the opportunity to manage their diabetes and potentially avoid or delay the complications of the disease, says Thomas Gardner, MD, MS, professor of ophthalmology and visual sciences at the Kellogg Eye Center at the University of Michigan. Here are the different treatment options for retinopathy and macular edema:
Laser treatment is used on the abnormal capillaries growing on the retina. The laser burns the outer areas of the retina in order to shrink the abnormal blood vessels. This saves central vision but sacrifices peripheral vision (everything you see on the side when looking straight ahead). Laser therapy can also help reduce the swelling of the macula (macular edema).
An experimental treatment may provide an alternative that preserves peripheral vision. The hope is that using low-intensity micro-pulses will treat retinopathy without damaging the tissue responsible for peripheral sight, says Rosen.
Treating Retinal Detachment
Surgery is the most common way to treat retinal detachment. There are different options available. Discuss which works for you with your eye doctor.
Anti-Vascular Endothelial Growth Factor Inhibitor Therapy
The most groundbreaking treatment for diabetic macular edema to date is anti-vascular endothelial growth factor (anti-VEGF) inhibitor therapy, says Bressler. After the eye is numbed, these drugs are injected into the eye to stop blood vessels from leaking.
“Instead of 1 out of 6 people losing vision [with laser treatment], maybe 1 out of 20 people lose vision [with anti-VEGF treatment],” says Bressler. And instead of only a third of people improving with laser, two-thirds improve with injections, he says.
There are three injectable anti-VEGF agents currently on the market: ranibizumab (Lucentis), aflibercept (Eylea), and bevacizumab (Avastin). The Food and Drug Administration (FDA) has not approved bevacizumab for the treatment of macular edema, but studies have shown it to be an effective treatment. Each medication is delivered in a series of injections, usually eight or nine in the first year and tapering off each year until you no longer need injections.
This treatment may also hold promise for the abnormal blood vessel growth of retinopathy. The FDA has recently approved ranibizumab for the treatment of retinopathy and aflibercept for the treatment of retinopathy if you also have macular edema. Anti-VEGF agents may reduce the growth of blood vessels and, in some cases, improve vision more than the traditional laser treatment, says Emily Chew, MD, deputy clinical director, and director of the Division of Epidemiology and Clinical Applications (DECA) at the National Eye Institute, part of the National Institutes of Health.
When anti-VEGF agents aren’t enough for a person with macular edema, Maturi will sometimes use a steroid implant, with doses too low to affect blood glucose as typical steroid treatments do, to further reduce retinal swelling. “They work on the retina quite well due to their proximity [to it],” he says. You have two options: a dexamethasone intravitreal implant (Ozurdex) or a fluocinolone acetonide intravitreal implant (Iluvien). There is a difference in side effects, so discuss your options with your eye doctor. In some cases, Maturi will use triple therapy to combat macular edema, using anti-VEGF agents, a steroid implant, and laser therapy simultaneously.
Drug trials are also underway to treat early stages of diabetic retinopathy, most likely with oral medication, which is more appealing than anti-VEGF injections. Researchers have identified molecules that can affect how the capillaries become clogged. The goal is to prevent capillaries from closing or to reopen them. “If we can address the disease right at the beginning, then we can change the whole course of it,” says Rosen.
Taking Care of Your Vision
The best way to preserve your vision is to manage your blood glucose. “When you have vision loss from diabetes, it indicates that your blood glucose levels have been abnormal for some time,” says Raj Maturi, MD, associate professor of clinical ophthalmology at Indiana University School of Medicine and partner at the Midwest Eye Institute in Indianapolis. High blood pressure and kidney problems are also risk factors for diabetic retinopathy. Read on for seven things you can do to lower your risk of developing retinopathy.
1. Manage your blood glucose. Keep your A1C (an overall measure of blood glucose control) in your target range.
2. Visit your eye doctor regularly. Optometrists and ophthalmologists can both detect signs of retinopathy, but only ophthalmologists can treat it.
3. Manage your blood lipids. Keep your cholesterol and triglycerides in your target range.
4. Manage your blood pressure. Keeping your blood pressure at 140 mmHg or lower has been shown to decrease retinopathy progression in people with type 2.
5. Avoid extremes. Avoid extreme and frequent blood glucose highs and lows, which can happen even if your A1C is within target range.
6. Protect your eyes. Maintain good eye protection habits, such as wearing sunglasses to reduce UV light exposure and taking a multivitamin that contains vitamin C, vitamin E, beta-carotene, and zinc.
7. Educate yourself. Take part in a diabetes education class or program to get answers to your diabetes questions and gain the knowledge, skills, and confidence you need to take charge of your health. You can find a program at:diabetes.org/findaprogram.