Diabetic retinopathy is a complication of diabetes that results from damage to the blood vessels of the light-sensitive tissue at the back of the eye (retina). At first, diabetic retinopathy may cause no symptoms or only mild vision problems. Eventually, however, diabetic retinopathy can result in blindness.
Diabetic retinopathy can develop in anyone who has type 1 diabetes or type 2 diabetes. The longer you have diabetes, and the less controlled your blood sugar is, the more likely you are to develop diabetic retinopathy.
To protect your vision, take prevention seriously. Start by carefully controlling your blood sugar level and scheduling yearly eye exams.
Too much sugar in your blood can damage the tiny blood vessels (capillaries) that nourish the retina. This can result in diabetic retinopathy and vision loss. Elevated blood sugar levels can also affect the eyes' lenses. With high levels of sugar over long periods of time, the lenses can swell, providing another cause of blurred vision.
Diabetic retinopathy is usually classified as early or advanced.
- Early diabetic retinopathy. Nonproliferative diabetic retinopathy (NPDR) is the most common type of diabetic retinopathy. It can be described as mild, moderate or severe. When you have NPDR, the walls of the blood vessels in your retina weaken. Tiny bulges protrude from the vessel walls, sometimes leaking or oozing fluid and blood into the retina. These bulges are called microaneurysms. As the condition progresses, the smaller vessels may close and the larger retinal veins may begin to dilate and become irregular in diameter. Nerve fibers in the retina may begin to swell. Sometimes the central part of the retina (macula) begins to swell, too. This is known as macular edema.
- Advanced diabetic retinopathy. Proliferative diabetic retinopathy (PDR) is the most severe type of diabetic retinopathy. When you have PDR, abnormal blood vessels grow in the retina. Sometimes the new blood vessels grow or leak into the clear, jelly-like substance that fills the center of your eye (vitreous). Eventually, scar tissue stimulated by the growth of new blood vessels may cause the retina to detach from the back of your eye. If the new blood vessels interfere with the normal flow of fluid out of the eye, pressure may build up in the eyeball, causing glaucoma. This can damage the nerve that carries images from your eye to your brain (optic nerve).
Diabetic retinopathy can happen to anyone who has diabetes. The risk is greater if you:
- Have poor control of your blood sugar level
- Have high blood pressure
- Have high cholesterol
- Are pregnant
- Are black or Hispanic
The longer you have diabetes, the greater your risk is of developing diabetic retinopathy.
It's possible to have diabetic retinopathy and not know it. In fact, it's uncommon to have symptoms in the early stages of diabetic retinopathy.
As the condition progresses, diabetic retinopathy symptoms may include:
- Spots or dark strings floating in your vision (floaters)
- Blurred vision
- Fluctuating vision
- Dark or empty areas in your vision
- Poor night vision
- Impaired color vision
- Vision loss
Diabetic retinopathy usually affects both eyes.
When to see a doctor
Careful management of your diabetes is the best way to prevent vision loss. If you have diabetes, see your eye doctor for a yearly dilated eye exam — even if your vision seems fine — because it's important to detect diabetic retinopathy in the early stages. If you become pregnant, your eye doctor may recommend additional eye exams throughout your pregnancy, because pregnancy can sometimes worsen diabetic retinopathy.
Contact your eye doctor right away if you experience sudden vision changes or your vision becomes blurry, spotty or hazy.
Diabetic retinopathy involves the abnormal growth of blood vessels in the retina. Complications can lead to serious vision problems:
- Vitreous hemorrhage. The new blood vessels may bleed into the clear, jelly-like substance that fills the center of your eye. If the amount of bleeding is small, you might see only a few dark spots or floaters. In more severe cases, blood can fill the vitreous cavity and completely block your vision. Vitreous hemorrhage by itself usually doesn't cause permanent vision loss. The blood often clears from the eye within a few weeks or months. Unless your retina is damaged, your vision may return to its previous clarity.
- Retinal detachment. The abnormal blood vessels associated with diabetic retinopathy stimulate the growth of scar tissue, which can pull the retina away from the back of the eye. This may cause spots floating in your vision, flashes of light or severe vision loss.
- Glaucoma. New blood vessels may grow in the front part of your eye and interfere with the normal flow of fluid out of the eye, causing pressure in the eye to build up (glaucoma). This pressure can damage the nerve that carries images from your eye to your brain (optic nerve).
- Blindness. Eventually, diabetic retinopathy, glaucoma or both can lead to complete vision loss.
Tests and diagnosis
Diabetic retinopathy is best diagnosed with a dilated eye exam. For this exam, your eye doctor will place drops in your eyes that make your pupils open widely for several hours. This allows your doctor to get a better view inside your eye. The drops may cause your close vision to be blurry until they wear off.
During the exam, your eye doctor will look for:
- Presence or absence of a cataract
- Abnormal blood vessels
- Swelling, blood or fatty deposits in the retina
- Growth of new blood vessels and scar tissue
- Bleeding in the clear, jelly-like substance that fills the center of the eye (vitreous)
- Retinal detachment
- Abnormalities in your optic nerve
In addition, your eye doctor may:
- Test your vision
- Measure your eye pressure to test for glaucoma.
As part of the eye exam, your doctor may do a retinal photography test called fluorescein angiography. First, your doctor will dilate your pupils and take pictures of the inside of your eyes. Then your doctor will inject a special dye into your arm. More pictures will be taken as the dye circulates through your eyes. Your doctor can use the images to pinpoint blood vessels that are closed, broken down or leaking fluid.
Optical coherence tomography
Your eye doctor also may request an optical coherence tomography (OCT) exam. This imaging test provides cross-sectional images of the retina that show the thickness of the retina, which will help determine whether fluid has leaked into retinal tissue. Later, OCT exams can be used to monitor how treatment is working.
Treatments and drugs
Treatment for diabetic retinopathy depends on the type of diabetic retinopathy you have, its severity and how well it may have already responded to previous treatments.
Early diabetic retinopathy
If you have nonproliferative diabetic retinopathy, you may not need treatment right away. However, your eye doctor will closely monitor your eyes to determine if you need treatment.
And, if you haven't been maintaining good blood sugar control, you'll need to work with your diabetes doctor (endocrinologist) to find out what additional steps you need to take to better control your diabetes. The good news is that when diabetic retinopathy is in the mild or moderate stage, good blood sugar control can slow the progression of diabetic retinopathy.
Advanced diabetic retinopathy
If you have proliferative diabetic retinopathy, you'll need prompt surgical treatment. Sometimes surgery is also recommended for severe nonproliferative diabetic retinopathy. Depending on the specific problems with your retina, options may include:
- Focal laser treatment. This laser treatment, also known as photocoagulation, can stop or slow the leakage of blood and fluid in the eye. It's done in your doctor's office or eye clinic. During the procedure, leaks from abnormal blood vessels are treated with laser burns. Focal laser treatment is usually done in a single session. Your vision will be blurry for about a day after the procedure. Sometimes you will be aware of small spots in your visual field that are related to the laser treatment. These usually disappear within weeks. If you had blurred vision from swelling of the central macula before surgery, however, you may not recover completely normal vision.
- Scatter laser treatment. This laser treatment, also known as panretinal photocoagulation, can shrink the abnormal blood vessels. It's also done in your doctor's office or eye clinic. During the procedure, the areas of the retina away from the macula are treated with scattered laser burns. The burns cause the abnormal new blood vessels to shrink and scar. Scatter laser treatment is usually done in two or more sessions. Your vision will be blurry for about a day after the procedure. Some loss of peripheral vision or night vision after the procedure is possible.
- Vitrectomy. This procedure can be used to remove blood from the middle of the eye (vitreous) as well as any scar tissue that's tugging on the retina. It's done in a surgery center or hospital under local or general anesthesia. During the procedure, the doctor makes a tiny incision in your eye. Scar tissue and blood in the eye are removed with delicate instruments and replaced with a salt solution, which helps maintain your eye's normal shape. Sometimes a gas bubble must be placed in the cavity of the eye to help reattach the retina. If a gas bubble was placed in your eye, you may need to remain in a facedown position until the gas bubble dissipates — often several days. You'll need to wear an eye patch and use medicated eyedrops for a few days or weeks. Vitrectomy may be followed or accompanied by laser treatment.
Surgery often slows or stops the progression of diabetic retinopathy, but it's not a cure. Because diabetes is a lifelong condition, future retinal damage and vision loss is possible. Even after treatment for diabetic retinopathy, you'll need regular eye exams. At some point, additional treatment may be recommended.
Researchers are studying new treatments for diabetic retinopathy, including medications that may help prevent abnormal blood vessels from forming in the eye. Some of these medications are injected directly into the eye to treat existing swelling or abnormal blood vessels.
If you have diabetes, reduce your risk of getting diabetic retinopathy by doing the following:
- Make a commitment to managing your diabetes. Make healthy eating and physical activity part of your daily routine. Take oral diabetes medications or insulin as directed.
- Monitor your blood sugar level. You may need to check and record your blood sugar level several times a day — more frequent measurements may be required if you're ill or under stress. Careful monitoring is the only way to make sure that your blood sugar level remains within your target range. Ask your doctor how often you need to test your blood sugar.
- Ask your doctor about a glycosylated hemoglobin test. The glycosylated hemoglobin test or hemoglobin A1C test reflects your average blood sugar level for the two- to three-month period before the test. For most people, the A1C goal is to be under 7 percent. If you've been meeting your blood sugar goals, your doctor will likely perform this test twice a year. But, if your A1C is higher than your goal, more frequent testing is recommended. Remember, keeping your blood sugar level as close to normal as possible slows the progression of diabetic retinopathy and reduces the need for surgery.
- Keep your blood pressure and cholesterol under control. High blood pressure and high cholesterol increase the risk of vision loss. Eating healthy foods, exercising regularly and losing excess weight can help. Sometimes medication is needed, too.
- If you smoke or use other types of tobacco, ask your doctor to help you quit. Smoking increases your risk of various diabetes complications, including diabetic retinopathy. Talk to your doctor about ways to stop smoking or to stop using other types of tobacco.
- Pay attention to vision changes. Yearly dilated eye exams are an important part of your diabetes treatment plan. Contact your eye doctor right away if you experience sudden vision changes or your vision becomes blurry, spotty or hazy.
Remember, diabetes doesn't necessarily lead to poor vision. Taking an active role in diabetes management can go a long way toward preventing complications.