What is diabetic retinopathy?
Retinopathy is a disease of the retina. The retina is the nerve layer that lines the back of your eye. It is the part of your eye that "takes pictures" and sends the images to your brain. Many people with diabetes get retinopathy. This kind of retinopathy is called diabetic retinopathy (retinal disease caused by diabetes).
Diabetic retinopathy can lead to poor vision and even blindness. Most of the time, it gets worse over many years. At first, the blood vessels in the eye get weak. This can lead to blood and other liquid leaking into the retina from the blood vessels. This is called non-proliferative retinopathy. And this is the most common retinopathy. If the fluid leaks into the centre of your eye, you may have blurry vision. Most people with non-proliferative retinopathy have no symptoms.
If blood sugar levels stay high, diabetic retinopathy will keep getting worse. New blood vessels grow on the retina. This may sound good, but these new blood vessels are weak. They can break open very easily, even while you are sleeping. If they break open, blood can leak into the middle part of your eye in front of the retina and change your vision. This bleeding can also cause scar tissue to form, which can pull on the retina and cause the retina to move away from the wall of the eye (retinal detachment). This is called proliferative retinopathy. Sometimes people don't have symptoms until it is too late to treat them. This is why having eye examinations regularly is so important.
Retinopathy can also cause swelling of the macula of the eye. This is called macular edema. The macula is the middle of the retina, which lets you see details. When it swells, it can make your vision much worse. It can even cause legal blindness.
What causes diabetic retinopathy?
If you are not able to keep your blood sugar levels in a target range, it can cause damage to your blood vessels. Diabetic retinopathy happens when high blood sugar damages the tiny blood vessels of the retina.
When you have diabetic retinopathy, high blood pressure can make it worse. High blood pressure can cause more damage to the weakened vessels in your eye, leading to more leaking of fluid or blood and clouding more of your vision.
What are the symptoms?
Most of the time, there are no symptoms of diabetic retinopathy until it starts to change your vision. When this happens, diabetic retinopathy is already severe. Having your eyes checked regularly can find diabetic retinopathy early enough to treat it and help prevent vision loss.
If you notice problems with your vision, call an eye doctor (ophthalmologist) right away. Changes in vision can be a sign of severe damage to your eye. These changes can include floaters, pain in the eye, blurry vision, or new vision loss.
How is diabetic retinopathy diagnosed?
An eye examination by an eye specialist (ophthalmologist or optometrist) is the only way to detect diabetic retinopathy. Having a dilated eye examination regularly can help find retinopathy before it changes your vision. On your own, you may not notice symptoms until the disease becomes severe.
Can diabetic retinopathy be prevented?
You can lower your chance of damaging small blood vessels in the eye by keeping your blood sugar levels and blood pressure levels within a target range. If you smoke, quit. All of this reduces the risk of damage to the retina. It can also help slow down how quickly your retinopathy gets worse and can prevent future vision loss.
If you have a dilated eye examination regularly, you and your doctor can find diabetic retinopathy before it has a chance to get worse. For most people, this will mean an eye examination every year. Finding retinopathy early gives you a better chance of avoiding vision loss and blindness.
How is it treated?
Surgery, laser treatment, or medicine may help slow the vision loss caused by diabetic retinopathy. You may need to be treated more than once as the disease gets worse.
Diabetes damages small blood vessels throughout the body, leading to reduced blood flow. When these changes affect the tiny blood vessels in the eyes, diabetic retinopathy may occur.
In the early stage of diabetic retinopathy, tiny blood vessels in the eye weaken and develop small bulges that may burst and leak into the retina. Later, new fragile blood vessels grow on the surface of the retina. These blood vessels may break and bleed into the eye, clouding vision and causing scar tissue to form.
The scar tissue may pull on the retina, leading to retinal detachment. Retinal detachment occurs when the retina separates from the wall of the eye. This can lead to vision loss.
You may have diabetic retinopathy for a long time without noticing any symptoms. Typically, retinopathy does not cause noticeable symptoms until significant damage has occurred and complications have developed.
Symptoms of diabetic retinopathy and its complications may include:
- Blurred, double, or distorted vision or difficulty reading.
- Floaters or spots in your vision.
- Partial or total loss of vision or a shadow or veil across your field of vision.
- Pain, pressure, or constant redness of the eye.
Diabetic retinopathy begins as a mild disease. During the early stage of the disease, the small blood vessels in the retina become weaker and develop small bulges called microaneurysms. These microaneurysms are the earliest signs of retinopathy and may appear a few years after the onset of diabetes. They may also burst and cause tiny blood spots (hemorrhages) on the retina. But they do not usually cause symptoms or affect vision. This is called non-proliferative retinopathy. At this stage, treatment is not required.
As retinopathy progresses, fluid and protein leak from the damaged blood vessels and cause the retina to swell. This may cause mild to severe vision loss, depending on which parts of the retina are affected. If the centre of the retina (macula) is affected, vision loss can be severe. Swelling and distortion of the macula (macular edema), which results from a buildup of fluid, is the most common complication of retinopathy. Macular edema treatment usually works to stop and sometimes reverse your loss of vision.
In some people, retinopathy gets worse over the course of several years and progresses to proliferative retinopathy. In these cases, reduced blood flow to the retina stimulates the growth (proliferation) of fragile new blood vessels on the surface of the retina. As the new blood vessels multiply, one or more complications may develop and damage the person's vision. These complications can include:
- The formation of scar tissue that pulls on the retina, which may lead to retinal detachment.
- Bleeding inside the eye (preretinal or vitreous hemorrhage).
- The growth of new blood vessels on the surface of the iris (rubeosis iridis), which eventually leads to a form of severe glaucoma called neovascular glaucoma.
Any of these later complications may cause severe, permanent vision loss.
What Increases Your Risk
Your risk for diabetic retinopathy depends largely on two things: how long you have had diabetes and whether or not you have kept good control of your blood sugar.
You can control some risk factors, which are things that may increase your risk for diabetic retinopathy and its complications. Risk factors that you can control include:
- Pregnancy. Women who have diabetes are at increased risk of developing retinopathy during pregnancy. In women who already have retinopathy when they become pregnant, the condition can become much worse during pregnancy.
- Consistently high blood sugar. High blood sugar levels increase your risk of retinopathy. Keeping your blood sugar levels in a target range can reduce your risk for diabetic retinopathy and can slow the progression of the disease if it has already started.
- High blood pressure. In general, people with diabetes who also have high blood pressure are more likely to develop complications that affect the blood vessels in the body, including those in the eyes.
- Delayed diagnosis and treatment. Getting a dilated eye examination will not prevent retinopathy. But it may reduce your risk of severe vision loss from complications of retinopathy. By detecting it early, you can get treatment that can prevent vision loss and delay the progression of the disease.
- Smoking. Although smoking has not been proved to increase the risk of retinopathy, smoking may make many of the other health problems faced by people with diabetes worse, including disease of the small blood vessels.
If you have type 2 diabetes and use the medicine rosiglitazone (Avandia, Avandamet) to treat your diabetes, you may have a higher risk for problems with the centre of the retina (the macula). Health Canada, the U.S. Food and Drug Administration (FDA), and the makers of the drug have warned that taking this medicine could cause swelling in the macula, which is called macular edema.
When should you call your doctor?
Call your doctor now if you have diabetes and notice:
- New or sudden vision changes.
- Floaters in your field of vision. Floaters often appear as dark specks, globs, strings, or dots. A sudden shower of floaters may be a sign of a retinal detachment, which is a serious complication of diabetic retinopathy.
- A new visual defect, shadow, or curtain across part of your vision. This is another sign of retinal detachment.
- Eye pain or a feeling of pressure in your eye.
- New or sudden vision loss. Sudden partial or complete vision loss is a symptom of many disorders that can occur within or outside the eye, including retinal detachment or bleeding within the eye. Sudden vision loss is always a medical emergency.
Call your doctor for an appointment if:
- You have more and more trouble doing everyday tasks (like driving or reading) because of your eyesight.
Watchful waiting is not okay if you have diabetes and notice changes in your vision.
If you have type 2 diabetes, even if you don't have any symptoms of eye disease, you still need to have your eyes and vision checked regularly by an eye specialist (ophthalmologist or optometrist). If you wait until you have symptoms, it's more likely that complications and severe damage to the retina will have already happened. These may be harder to treat. You could end up with permanent vision loss.
If you have type 1 diabetes, are age 10 or older, and were diagnosed 5 or more years ago, you should have your eyes checked even if you don't have symptoms. If you wait until you have symptoms, it's more likely that complications and severe damage to the retina will have happened. These may be harder to treat. And the damage may be permanent.
Watchful waiting is not an option if you already have diabetic retinopathy but don't have symptoms or vision loss. You will need to go back to your ophthalmologist for frequent checkups (every few months in some cases) so that your doctor can closely monitor changes in your eyes. There is no cure for the disease. But treatment can slow its progression. Your ophthalmologist can tell you how often you need to be checked.
Examinations and Tests
Diabetic retinopathy can be detected during a dilated eye examination by an ophthalmologist or optometrist. An examination by your primary doctor, during which your eyes are not dilated, is not an adequate substitute for a full examination done by an ophthalmologist or optometrist. Eye examinations for people with diabetes can include:
- Visual acuity testing. Visual acuity testing measures the eye's ability to focus and to see details at near and far distances. It can help detect vision loss and other problems.
- Ophthalmoscopy and slit lamp examination. These tests allow your doctor to see the back of the eye and other structures within the eye. They may be used to detect clouding of the lens (cataract), changes in the retina, and other problems.
- Gonioscopy. Gonioscopy is used to find out whether the area where fluid drains out of your eye (called the drainage angle) is open or closed. This test is done if your doctor thinks you may have glaucoma, a group of eye diseases that can cause blindness by damaging the optic nerve.
- Tonometry. This test measures the pressure inside the eye, which is called intraocular pressure (IOP). It is used to help detect glaucoma. Diabetes can increase your risk of glaucoma.
Your doctor may also do a test called an optical coherence tomography (OCT) to check for fluid in your retina. Sometimes a fluorescein angiogram is done to check for and locate leaking blood vessels in the retina, especially if you have symptoms, such as blurred or distorted vision, that suggest damage to or swelling of the retina.
Fundus photography can track changes in the eye over time in people who have diabetic retinopathy and especially in those who have been treated for it. Fundus photography produces accurate pictures of the back of the eye (the fundus). An eye doctor can compare photographs taken at different times to watch the progression of the disease and find out how well treatment is working. But the photos do not take the place of a full eye examination.
Early detection and treatment of diabetic retinopathy can help prevent vision loss. For people in whom diabetic retinopathy has not been diagnosed, Diabetes Canada recommends that screening be done based on the following guidelines:
- People with type 1 diabetes who are age 15 and older should have a dilated eye examination within 5 years after diabetes is diagnosed and then every year.footnote 1
- People with type 2 diabetes should have an examination as soon as diabetes is diagnosed and then every year. If your eye examination results are normal or you have a very small amount of retinopathy, your doctor may consider follow-up examinations every 1 to 2 years.footnote 1
- If you are diagnosed with retinopathy, you may need frequent eye examinations.
- Women who have type 1 or type 2 diabetes and who are planning to get pregnant should have an examination before getting pregnant, during the first 3 months (first trimester) of pregnancy, and within the first year after the baby is born. The eye doctor can decide whether you need further screening for retinopathy during pregnancy based on the results of the first-trimester examination.footnote 2
Note: Pregnant women who develop gestational diabetes are not at risk for diabetic retinopathy and do not need to be screened for it. (But women who develop gestational diabetes during pregnancy have a greater chance of developing type 2 diabetes later in life, which can put them at increased risk for retinopathy and other eye problems.)
People who have diabetes are also at increased risk for other eye diseases, including glaucoma and cataracts. Regular dilated eye examinations can help detect these diseases early and prevent or delay vision loss.
There is no cure for diabetic retinopathy. But laser treatment (photocoagulation) is usually very effective at preventing vision loss if it is done before the retina has been severely damaged. Surgical removal of the vitreous gel (vitrectomy) may also help improve vision if the retina has not been severely damaged. Sometimes injections of an anti-VEGF (vascular endothelial growth factor) medicine or an anti-inflammatory medicine help to shrink new blood vessels in proliferative diabetic retinopathy. Because symptoms may not develop until the disease becomes severe, early detection through regular screening is important. The earlier retinopathy is detected, the easier it is to treat and the more likely vision will be preserved.
You may need treatment for diabetic retinopathy if:
- It has affected the centre (macula) of the retina.
- Abnormal new blood vessels have started to appear.
- Your side (peripheral) vision has been severely damaged.
If the macula has been damaged by macular edema, anti-VEGF medicine, such as aflibercept or ranibizumab, may help. Steroids may be injected into the eye. Sometimes an implant, such as Iluvien, may be placed in the eye to release a small amount of corticosteroid over time. If the retina hasn't been severely damaged, laser treatment or vitrectomy may help with macular edema.
Surgical removal of the vitreous gel (vitrectomy) is done when there is bleeding (vitreous hemorrhage) or retinal detachment, which are rare in people with early-stage retinopathy. Vitrectomy is also done when severe scar tissue has formed.
Treatment for diabetic retinopathy is often very effective in preventing, delaying, or reducing vision loss. But it is not a cure for the disease. People who have been treated for diabetic retinopathy need to be monitored frequently by an eye doctor to check for new changes in their eyes. Many people with diabetic retinopathy need to be treated more than once as the condition gets worse.
Also, controlling your blood sugar levels is always important. This is true even if you have been treated for diabetic retinopathy and your eyes are better. In fact, good blood sugar control is especially important in this case so that you can help keep your retinopathy from getting worse.
People with diabetes who have any signs of retinopathy need to be examined as soon as possible by an ophthalmologist.
There are steps you can take to reduce your chance of vision loss from diabetic retinopathy and its complications:
- Control your blood sugar levels. Keep blood sugar levels in a target range by eating a healthful diet, frequently monitoring your blood sugar levels, getting regular physical exercise, and taking insulin or medicines for type 2 diabetes if prescribed.
- Control your blood pressure. Retinopathy is more likely to progress to the severe form and macular edema is more likely to occur in people who have high blood pressure. It is not clear whether treating high blood pressure can directly affect long-term vision. But in general, keeping blood pressure levels in a target range can reduce the risk of many different complications of diabetes. For more information about how to control your blood pressure, see the topic High Blood Pressure.
- Have your eyes examined by an eye specialist (ophthalmologist or optometrist) every year. Screening for diabetic retinopathy and other eye problems will not prevent diabetic eye disease. But it can help you avoid vision loss by allowing for early detection and treatment.
- See an ophthalmologist if you have changes in your vision. Changes in vision—such as floaters, pain or pressure in the eye, blurry or double vision, or new vision loss—may be symptoms of serious damage to your retina. In most cases, the sooner the problem can be treated, the more effective the treatment will be.
The risk for severe retinopathy and vision loss may be even less if you:
- Don't smoke. Although smoking has not been proved to increase the risk of retinopathy, smoking may aggravate many of the other health problems faced by people with diabetes, including disease of the small blood vessels.
- Avoid hazardous activities. Certain physical activities, like weight lifting or some contact sports, may trigger bleeding in the eye through impact or increased pressure. Avoiding these activities when you have diabetic retinopathy can help reduce the risk of damage to your vision.
- Get adequate exercise. Exercise helps keep blood sugar levels in a target range, which can reduce the risk of vision damage from diabetic retinopathy. Talk to your doctor about what kinds of exercise are safe for you.
Surgical treatment for diabetic retinopathy is removal of the vitreous gel (vitrectomy). Vitrectomy does not cure the disease. But it may improve vision in people who have developed bleeding into the vitreous gel (vitreous hemorrhage), retinal detachment, or severe scar tissue formation.
Unfortunately, by the time some people are diagnosed with retinopathy (especially late-stage retinopathy), it is often too late for vitrectomy to provide much benefit. Even with treatment, vision may continue to decline.
Early detection of retinopathy through dilated eye examinations can help you decide to have surgery when it is most effective.
What to think about
After a person has had most of the vitreous gel removed by vitrectomy, surgery to remove scar tissue or to repair a new retinal detachment may be needed.
Vitrectomy is usually done as an outpatient surgery.
Laser treatment (photocoagulation) can be an effective treatment for diabetic retinopathy. But it does not cure the disease. It can prevent, delay, and sometimes reverse vision loss. Without either laser treatment or surgery, vision loss caused by diabetic retinopathy and its complications may get worse until blindness occurs. So early treatment is vital to slowing vision loss, which can happen quickly.
When diabetic retinopathy causes bleeding (hemorrhage) into the vitreous gel, extensive scar tissue formation, or retinal detachment, surgical removal of the vitreous gel (vitrectomy) may be needed before laser treatment is considered.
Unfortunately, by the time some people are diagnosed with diabetic retinopathy, it is often too late for treatment to provide much benefit. Even with treatment, vision will continue to decline.
Early detection of retinopathy through dilated eye examinations can provide the opportunity to have laser treatment when it is most effective.
Other treatment choices
Laser photocoagulation uses the heat from a laser to seal or destroy abnormal, leaking blood vessels in the retina. It can cause the abnormal, weak blood vessels to shrink.
Some anti-VEGF (vascular endothelial growth factor) medicines, such as aflibercept and ranibizumab, can help treat macular edema from diabetic retinopathy.
What to think about
Pan-retinal laser treatment is used to treat several spots on the retina during one or, most often, two sessions. It reduces the risk of serious bleeding and the progression of severe proliferative retinopathy.
Laser photocoagulation can result in some loss of vision, because it destroys some of the nerve cells in the retina and can cause the abnormal blood vessels to go away. With pan-retinal photocoagulation, this most often affects the outside (peripheral) vision, because the laser is directed at that area. Your vision may be worse right after treatment. But vision loss caused by laser treatment is mild compared with the vision loss that may be caused by untreated retinopathy.
- Diabetes Canada Clinical Practice Guidelines Expert Committee, et al. (2018). Retinopathy. Canadian Journal of Diabetes, 42(Suppl 1): S210–S216. DOI: 10.1016/j.jcjd.2017.10.027. Accessed October 15, 2018.
- Diabetes Canada Clinical Practice Guidelines Expert Committee, et al. (2018). Diabetes and pregnancy. Canadian Journal of Diabetes, 42(Suppl 1): S255–S282. DOI: 10.1016/j.jcjd.2017.10.038. Accessed October 15, 2018. [Erratum in Canadian Journal of Diabetes 42(3): 337. DOI: 10.1016/j.jcjd.2018.04.006.] Accessed October 12, 2018.
Other Works Consulted
- American Academy of Ophthalmology (2014). Diabetic retinopathy summary benchmark—2014 (Preferred Practice Pattern guidelines). http://one.aao.org/summary-benchmark-detail/diabetic-retinopathy-summary-benchmark--october-20. Accessed December 15, 2014.
- American Optometric Association (2014). Evidence-based clinical practice guideline: Eye care of the patient with diabetes mellitus. http://www.aoa.org/optometrists/tools-and-resources/clinical-care-publications/clinical-practice-guidelines?sso=y. Accessed December 15, 2014.
- Brownlee M, et al. (2011). Complications of diabetes mellitus. In S Melmed et al., eds., Williams Textbook of Endocrinology, 12th ed., pp. 1462–1551. Philadelphia: Saunders.
- Fletcher EC, et al. (2011). Retina. In P Riordan-Eva, JP Whitcher, eds., Vaughan and Asbury's General Ophthalmology, 18th ed., pp. 190–221. New York: McGraw-Hill.
- Mohamed QA, et al. (2011). Diabetic retinopathy (treatment), search date June 2010. BMJ Clinical Evidence. Available online: http://www.clinicalevidence.com.
Current as of: July 28, 2021
Author: Healthwise Staff
Adam Husney MD - Family Medicine
Donald Sproule MDCM, CCFP - Family Medicine
Kathleen Romito MD - Family Medicine
Carol L. Karp MD - Ophthalmology