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Here’s a look at the ways diabetes can impact your eyesight — and the importance of regular eye exams.
If you have type 1 or type 2 diabetes, it’s important to know that high blood sugar and other diabetes-related health issues can affect your eyes and your vision. Often, the eye-damaging effects don’t have early warning signs, so along with all the steps your doctor recommends for managing diabetes, make sure you’re also getting regular eye exams. Working with your optometrist to spot and then address diabetes-related eye issues during their earliest, most treatable stages can help you sidestep potentially serious vision problems down the road.
That risk to your vision is very real: Diabetes-related eye diseases are the leading cause of newly diagnosed blindness in American adults ages 20 to 74, according to the Centers for Disease Control and Prevention (CDC). But the CDC has hopeful news too, reporting that 90% of diabetes-related vision loss can be prevented. How? By controlling your blood sugar and getting the eye care you need.
That sounds simple, yet more than half of people with diabetes skip regular eye exams. Don’t make that mistake. Learning more about how diabetes can affect your vision — and about the many research-proven ways to keep your eyes healthy — can help you protect your precious eyesight. This clear and comprehensive guide is a great place to start.
How common are diabetes-related vision problems?
Very common. Here’s a peek at the stats:
- About 1 in 3 people who are older than 40 with diabetes have signs of diabetic retinopathy, the most common reason for vision loss in those with diabetes.
- About 1 in 50 who have long-standing diabetes (at least 10 years) develop diabetic macular edema, which is vision-threatening swelling inside the eyes.
- Adults with diabetes are also two to five times more likely to have cataracts, compared with people who don’t have diabetes. In addition, they are more likely to develop cataracts at a younger age. In fact, among people age 45 and older with diabetes, cataracts cause vision loss in about 1 out of every 11 cases.
- Diabetes doubles your risk of glaucoma.
- Diabetes increases the odds that you’ll experience age-related macular degeneration especially if you already have diabetic retinopathy.
A little less alarming — but just as important to your day-to-day life — is the fact that high blood sugar levels can affect the lenses of your eyes in ways that cause temporary blurry vision. That could make it more difficult for your optometrist to measure your vision accurately and give you the right prescription for glasses or contact lenses, says Robert Africano, O.D., an optometrist and clinical preceptor at North Carolina Primary Vision Care Associates inside America’s Best Contacts & Eyeglasses in Charlotte, North Carolina.
Eye exams are an essential part of a diabetes treatment plan. Book an appointment today!
How is diabetes connected to the health of the eyes?
Over time, the elevated blood sugar associated with diabetes can damage the tiny blood vessels that carry nutrients and oxygen to your retina. (The retina is the light-sensing tissue at the backs of your eyes.) Once those blood vessels are weakened, they’re more prone to leakage. In turn, that leakage can lead to a buildup of fluid that causes swelling and clouds your eyes’ normally clear lenses.
In addition, your eyes may start growing new blood vessels to try to compensate for the damaged ones. But the high level of glucose in your system makes those new vessels weak, and they can bleed into your eye. This is another cause of dangerous pressure and can even lead to scarring.
Diabetes also results in high blood pressure in 2 out of 3 people with the disease, and it can lead to high cholesterol; both conditions are additional threats to the health of the blood vessels in your eyes.
“We are always serious about blood sugar,” Dr. Africano says. “Keeping your blood sugar under good control can prevent diabetes-related eye problems from happening, and it can help slow down and even stop damage if you do have a diabetic eye disease.”
How do I know if I’m developing a diabetes-related eye disease?
Well, you may not know in the early stages: Diabetes-related eye diseases can progress without causing any eyesight changes or symptoms at all. That’s why making regular visits to your optometrist is a crucial part of your care: They can spot very early warning signs during an exam.
“Your eye doctor is essentially looking into your body when they do an eye exam,” Dr. Africano says. “Diabetes can affect your whole body, including your kidneys and your nerves, but your eyes are the only place where a doctor can directly see what’s going on.”
The American Diabetes Association and the National Institute of Diabetes and Digestive and Kidney Diseases both recommend that people with type 2 diabetes have a comprehensive eye exam as soon as they’re diagnosed. This should include dilation of your pupils, so that your optometrist can view the backs of your eyes.
People with type 1 diabetes have a little more leeway, if they’re at a safe blood sugar level and have no retinopathy. Annual eye exams are still recommended and under no circumstances should you go longer than five years without an exam.
Regardless of diabetes type, if any retinopathy is found, you should have a dilated eye exam at least once a year. And if retinopathy is progressing or threatening your sight, you’ll likely need even more frequent checks. See your eye doctor right away, however — don’t wait for your annual exam — if your vision suddenly changes or becomes blurry, hazy, or spotty.
Let’s run through some of the common diabetes-related eye issues talked about above and how your eye doctor can diagnose and treat them.
What it is: Simply put, diabetic retinopathy is disease or damage in the retinas. (“Pathy” means “disease,” so “retinopathy” means “retinal disease.”) It is caused by the high blood sugar associated with diabetes.
Nonproliferative retinopathy is the most common form. Here, capillaries in the backs of the eyes swell and form pouches, which block the blood flow. The condition can progress from mild to moderate to severe as more and more blockages occur.
Nonproliferative retinopathy may then develop into proliferative retinopathy. In this stage, blood flow to the retina worsens due to the damaged blood vessels. New and fragile blood vessels grow to replace them in the retina. These can leak blood, which interferes with your vision. This may also prompt the growth of scar tissue, which can put extra tension on your retina and raise your risk of a vision-robbing emergency called retinal detachment.
How it’s detected: You’ll likely see no vision changes from early-stage retinopathy, Dr. Africano says. In later stages, you may have the following symptoms:
- Blurry vision
- Floaters (spots or shadows that move across your field of vision)
- Trouble seeing at night
- Blank or dark areas in your field of vision
- Eyesight that changes from clear to blurry at times, or even blindness
Your optometrist can see much more. During a dilated eye exam, the doctor can see the beginnings of blood vessel changes and other problematic signs.
Your doctor may also perform a test called fluorescein angiography, which uses a special dye and a camera to see the blood vessels at the backs of your eyes more closely. They’ll be looking for evidence of leaks and the growth of new, abnormal blood vessels. Another test, called optical coherence tomography (OCT), takes cross-section pictures of the retina in order to better examine all of its layers.
How to treat it: That depends on the stage of the disease. In the early stages, good blood sugar control is your main plan of action, Dr. Africano says. You’ll want to work closely with the health care practitioner who manages your diabetes, whether that’s your primary care physician or a specialist in endocrinology.
Keeping your blood sugar within a healthy range can not only prevent the progression of retinopathy but also sometimes restore some vision you may have already lost, according to the American Academy of Ophthalmology. Equally important in the early stages of diabetes: Controlling the high blood pressure and high cholesterol that can happen with poorly managed diabetes.
If you have proliferative retinopathy, anti-VEGF injections are the treatment of choice. Here are the basics: VEGF, or vascular endothelial growth factor, is a protein your body produces that lets it create new blood vessels when you need them. That may sound like a good thing, but sometimes your body can make too much VEGF, and the blood vessels that form in your eye are abnormal. Enter anti-VEGF injections, which are used to reduce the amount of the culprit protein.
If you have advanced proliferative retinopathy and the bleeding or scarring is widespread, you may need eye surgery called a vitrectomy. This procedure replaces the gel-like fluid in your eyes with a safe, clear fluid such as silicone oil or saline. At the same time, the eye surgeon can remove scar tissue and repair the damage to your retinas.
Have questions about your vision or eye health? Reach out to your America’s Best optometrist, who is an important part of your care team. Book an appointment today!
What it is: Macular edema is closely related to diabetic retinopathy. As retinopathy progresses and the capillary walls weaken, there is abnormal leakage that causes swelling of the macula. The macula is the middle area of your retina that’s responsible for clear vision when you look straight ahead, as well as your ability to see things in fine detail.
This condition is painless and may have no early symptoms. But as it worsens, your central vision may start to look wavy or blurred. You may notice that it’s difficult to read or that colors look faded. If macular edema is left untreated, it can lead to severe vision loss or blindness.
How it’s detected: Once again, your best tool is regular eye exams, because even if you can’t spot any early symptoms, your optometrist can. They’ll dilate your pupils to get a clear view of the backs of them (where your retinas are). They may use other tests to look for blood vessel leakage or cysts in the macula.
Two of the tests we just mentioned are useful here too: A fluorescein angiography test uses dye and a special camera to look for leaking blood vessels and measure the degree of leakage. And an OCT test scans the retina and checks its thickness, allowing your doctor to assess whether there is leakage or swelling.
How to treat it: If you have diabetic macular edema, you will need prompt treatment to reduce the swelling. One treatment is injections of the same anti-VEGF medications used to treat retinopathy. You may need injections once a month at first to keep VEGF in check and stop or slow the progression of the edema, Dr. Africano notes.
Corticosteroids can also be used. These are medicines that reduce swelling and make your vision sharper. They can be delivered via an implant, which may sound scary but is simply a tiny capsule injected into your eye that releases the steroids gradually.
Then there are laser treatments: Focal laser therapy is often used to target the specific areas responsible for retinal leakage and repair those areas. If the damage is more severe, your doctor might use another laser treatment called scatter photocoagulation (or panretinal photocoagulation). It can lower the threat of blindness posed by a detached retina or severe diabetic retinopathy.
What they are: Cataracts can occur when a higher than healthy level of sugar (glucose) in your blood, due to diabetes, raises the level of glucose in a fluid in your eyes called the aqueous humor. Glucose helps nourish your retinas, but too much of it can permeate the lenses in your eyes, increasing levels of a compound called sorbitol that can make the lens cloudy, which can lead to the formation of a cataract.
While cataracts are a common development as we age, the risk is higher in people with diabetes, and the risk is even higher in those who develop the disease earlier.
How they’re detected: As cataracts develop, you may notice cloudy, blurry, or misty-looking vision, sensitivity to glare, or halos around lights — or you may notice that everything looks a little faded or yellow. During a professional eye exam, the doctor will use high-intensity light combined with a microscope, often while your eyes are dilated or after applying drops with a dye in them. He’ll closely examine all of the parts of your eyes; in the case of suspected cataracts, he’ll particularly be looking for signs of cloudiness on the surface of your lenses.
How to treat it: No surprise here: Blood sugar control is key to lowering your risk of cataracts related to diabetes. In one study, people who reduced their A1c by just 1% reduced their cataract risk by 19%.
Day to day, you can probably compensate if you have only mild cataracts: Wearing sunglasses during the day will help minimize glare, or you might consider getting anti-reflective lenses for your glasses. But for more advanced cataracts, you may need surgery to replace the lenses in your eyes.
Keep in mind that cataracts often go hand in hand with macular edema, and if that’s the case for you, your doctor may also recommend the anti-VEGF injections, corticosteroid drops or implants, or laser treatments discussed above.
What it is: Glaucoma is an umbrella term that describes an array of conditions that damage your optic nerve, which carries signals from your eyes to your brain. The damage is usually due to unnaturally high pressure in your eyes.
Diabetes specialists and vision experts have long known that there’s a connection between high blood sugar and a higher risk of glaucoma. It’s a relationship that goes both ways: People with diabetes have a higher risk of glaucoma, and people with open-angle glaucoma (the most common type) have a higher risk of developing diabetes, according to the Glaucoma Research Foundation.
How it’s detected: Glaucoma is yet another sight thief. Usually, it has no symptoms early on, when nerve fibers are just beginning to die off. As glaucoma progresses, however, you may notice blurry vision, halos around lights, blind spots in your peripheral vision, or headaches with sharp pain.
Your doctor can detect early signs of glaucoma during an eye exam by measuring the pressure inside your eye. There are several ways to do this; the one that you’ve probably encountered in your regular eye exam is the air puff test. Your doctor shoots a puff of warm air against your eyeball, using a device called a tonometer, in order to measure the pressure in your eyes. Unusually high pressure is a sign of glaucoma.
Your eye doctor may also check the thickness of your cornea (the clear window at the front of your eye), which can be related to eye pressure, as well as the angle where your cornea and iris meet, to see if it’s open and wide or narrow and closed. Diabetes develops slowly and leads to a wide and open angle between the iris and cornea. Observing this can help the doctor make a glaucoma diagnosis.
How to treat it: The most common form of glaucoma, primary open-angle glaucoma, is usually treated with prescription eye drops that lower the pressure inside the eyes. If the medications aren’t effective, your eye doctor might recommend laser procedures or surgery.
A more serious form of glaucoma, neovascular glaucoma, might require you to take anti-VEGF medications or have surgery to improve fluid drainage in your eyes.
Diabetes can be a difficult diagnosis to receive, but it is possible to manage with good lifestyle habits and medical care. Making sure you include your eye doctor on your diabetes team is an important step in making sure your vision doesn’t become a victim of the disease.
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