Diabetes affects more than 34 million people in the United States, and prediabetes impacts an additional 88 million Americans. While diabetic complications are commonly thought of as associated with heart, kidney, or nerve damage, diabetes also puts you at risk for vision loss and other eye health problems. In fact, diabetes is the leading cause of vision loss in people ages 18 to 64 years old, according to the American Diabetes Association (ADA).
To help promote eye health, we are examining the ways in which diabetes can impact your eyes, eye complications you may experience, and how you can treat these diabetes-related eye conditions.
What Does Diabetes Do to Your Eyes?
Any type of eye problem that affects people with diabetes falls under the umbrella term of diabetic eye disease. Diabetic eye disease can include diabetic retinopathy, diabetic macular edema, cataracts, and glaucoma.
The increased blood sugar levels associated with diabetes can impact your eyes in a number of ways. The most common impact is weakened blood vessels that leak into your eye causing swelling that can damage the sensitive structures in your eye. Diabetes can also cloud the lens of your eye, and is associated with an increased risk of elevated eye pressure that can damage your optic nerve and lead to vision loss.
Diabetic Eye Problems
There are four diabetic eye diseases that affect the eyes in different ways.
With diabetic retinopathy, damage occurs to blood vessels in the retina, the thin layer of light-sensitive tissue that lines the back of the eye. Diabetic retinopathy is the most common and the most serious diabetic eye disease, according to the ADA. This condition is more common in people who have poor control of their blood sugar or who have had diabetes for a long time.
There are two types of diabetic retinopathy: Nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). NPDR is considered the less advanced stage of diabetic retinopathy when blood vessels leak into the retina and cause swelling, which can lead to macular edema (see below). Alternatively, blood vessels in the retina can become closed off depriving the macula of blood and leading to a loss of vision. Closure of retinal blood vessels can also cause PDR where abnormal blood vessels grow on the surface of the retina (neovascularization). These blood vessels can bleed into the vitreous, the clear, gel-like substance of the eye. This can cause floaters that impact parts of your vision. If there is substantial bleeding, all vision might be blocked. These abnormal blood vessels can also form scar tissue that can damage the macula or cause a retinal detachment.
Signs of diabetic retinopathy include floaters, blurry vision, problems seeing at night, dark areas in your vision, or experiencing faded or washed-out colors. About 33% of people with diabetes above the age of 40 have diabetic retinopathy, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
Diabetic Macular Edema
The macula is the central part of the retina that allows for sharp, detailed vision. When fluid leaks from damaged blood vessels caused by diabetic retinopathy it can build up in the area of the macula where it causes swelling. Macular swelling causes blurry, distorted vision with a loss of color clarity and is the most common cause of vision loss in people with diabetes.
In some cases, macular edema can lead to blindness.
In people with healthy eyes, a transparent, flexible lens sits behind the iris and pupil to allow for clear vision. As we age, proteins in the lens can start to break down and clump together making the lens cloudy and increasingly opaque over time. This cloudy lens is called a cataract, and surgery is required to remove it.
People with diabetes who have high glucose levels can develop cataracts much more quickly because excess glucose is converted to sorbitol that collects in the lens. This leads to cataracts being two to five times more frequent in patients with diabetes than those without it.
Glaucoma is a medical term to describe different diseases often associated with elevated eye pressure that affect the optic nerve — the nerve connecting the eye to the brain. Once damage occurs to the optic nerve, visual information from the retina is impeded from reaching the vision centers of your brain. Over time, loss of vision can occur. In fact, glaucoma is the leading cause of irreversible blindness in adults over the age of 60.
Those with diabetes are twice as likely as the general population to develop glaucoma. In particular, a severe form of diabetic retinopathy can lead to the growth of abnormal blood vessels on the iris, which can cause a type of angle-closure glaucoma called neovascular glaucoma. Even the steroids used to treat macular edema can lead to glaucoma.
Eye Complications of Diabetes
Your risk of developing diabetic eye disease increases if you have untreated high blood pressure or high blood sugar levels. Smoking and high cholesterol are two other risk factors that can lead to diabetic eye disease.
In general, diabetic eye diseases take 10 or more years to develop. You may not initially have symptoms, which further highlights the importance of having an annual eye exam to screen for eye complications before they occur.
Aside from the four types of eye diseases diabetes can cause, you may also experience double vision due to uncontrolled diabetes. This complication occurs when a lack of circulation damages the muscles that help your eyes move. When these muscles do not work together, your brain processes two images instead of one, resulting in double vision. Generally, this vision issue subsides once your diabetes is under control.
Diabetes can also affect your immune system and lead to other common eye complications, such as conjunctivitis and other eye infections. As a precaution, wash your hands before and after touching your eyes, such as when putting in contacts.
Another eye complication from diabetes involves pregnant women, who are more at risk for diabetic retinopathy and vision loss. The speed in which you can develop these eye diseases is expedited due to hormonal changes and blood pressure changes during pregnancy.
How to Prevent Diabetic Eye Problems
Simply having diabetes does not mean you will eventually have eye problems. There are measures you can take to prevent eye diseases from developing. In fact, the Centers for Disease Control and Prevention (CDC) estimates 90% of vision loss from diabetes is preventable.
To start, schedule an annual comprehensive eye exam with your eye doctor. Early detection is one of the biggest ways to maintain healthy eyes, but past studies have shown only about 40% of people with diabetes actually receive a yearly exam.
As for other preventive measures, manage your A1c, blood pressure, and cholesterol, as high levels of any of these three can lead to diabetic eye disease or make it worse. Talk to your primary care doctor about a diet to help you manage your diabetes. Controlling your blood sugar levels can either stop vision loss or help bring your vision back. Physical activity can also help control your diabetes.
Diabetic Eye Disease Treatment
In the event diet and exercise does not have a positive effect on your eye symptoms, there are other treatments available to manage diabetic eye disease. Your ophthalmologist may recommend medications or, in advanced cases, you may need a surgical procedure to alleviate symptoms.
Anti-VEGF intraocular injections are a common treatment used to reduce swelling in the macula caused by macular edema and to treat diabetic retinopathy. Vascular endothelial growth factor (VEGF) is a protein in your body that helps create and repair blood vessels. Too much of this protein can lead to abnormal blood vessel growth. This medication blocks the VEGF protein from growing new blood vessels and can also stop fluid leaks, therefore slowing down vision loss.
Injections are administered during an in-office procedure. Typically, there are three initial treatments in the first three months followed by a series of injections over a period of several years.
During a laser treatment, a highly concentrated beam of light passes through the cornea, lens, and vitreous to treat the retina. The light damages retinal tissue and forms scars as it heals. These scars help seal off leaking blood vessels or destroy areas of retinal tissue damaged by poor circulation.
The main purpose of laser treatment is to keep diabetic eye disease from progressing and help prevent severe vision loss or blindness. Focal/grid laser treatment focuses on a small area of the retina to treat macular edema caused by diabetes. Scatter laser treatment, also called panretinal photocoagulation (PRP), focuses on a larger area of the retina to treat abnormal blood vessel growth.
If diabetes leads to the formation of cataracts, the only option available is surgery. Cataract surgery removes the cloudy, hardened lens and replaces it with a clear, artificial lens, called an intraocular lens (IOL). There are standard and premium cataract surgery options available. Premium cataract surgery can reduce or even eliminate the need for glasses.
Glaucoma Laser Treatments and Surgical Options
Depending on the type of glaucoma associated with diabetes, different treatment options are available. Primary open-angle glaucoma patients are treated the same as non-diabetic patients — with medications, lasers, and surgery, as needed. For neovascular glaucoma, lasers and injections can be used to treat the diabetic retinopathy, but the angle-closure glaucoma usually needs to be treated with a shunt to help restore drainage. A combination of these glaucoma treatments might be required to treat steroid-induced glaucoma, which can be a side-effect of steroid injections used to treat diabetic macular edema.