What is diabetic retinopathy?

Diabetic retinopathy is a complication of diabetes and a leading cause of blindness. It occurs when diabetes damages the tiny blood vessels inside the retina, the light-sensitive tissue at the back of the eye. A healthy retina is necessary for good vision.

If you have diabetic retinopathy, at first you may notice no changes to your vision. But over time, diabetic retinopathy can get worse and cause vision loss. Diabetic retinopathy usually affects both eyes.

What are the stages of diabetic retinopathy?

Diabetic retinopathy has four stages:

Mild Nonproliferative Retinopathy. At this earliest stage, microaneurysms occur. They are small areas of balloon-like swelling in the retina's tiny blood vessels.

Moderate Nonproliferative Retinopathy. As the disease progresses, some blood vessels that nourish the retina are blocked.

Severe Nonproliferative Retinopathy. Many more blood vessels are blocked, depriving several areas of the retina with their blood supply. These areas of the retina send signals to the body to grow new blood vessels for nourishment.

Proliferative Retinopathy. At this advanced stage, the signals sent by the retina for nourishment trigger the growth of new blood vessels. This condition is called proliferative retinopathy. These new blood vessels are abnormal and fragile. They grow along the retina and along the surface of the clear, vitreous gel that fills the inside of the eye.

By themselves, these blood vessels do not cause symptoms or vision loss. However, they have thin, fragile walls. If they leak blood, severe vision loss and even blindness can result.

Who is at risk for diabetic retinopathy?

All people with diabetes--both type 1 and type 2--are at risk. That's why everyone with diabetes should get a comprehensive dilated eye exam at least once a year early in diabetes and more frequently as directed by their ophthalmologist. Approximately 25% of Canadians diagnosed with diabetes have some stage of diabetic retinopathy. If you have diabetic retinopathy, we may recommend treatment to help prevent worsening of your eye disease.

During pregnancy, diabetic retinopathy may be a problem for women with diabetes. To protect vision, every pregnant woman with diabetes should have a comprehensive dilated eye exam as soon as possible. Additional exams during the pregnancy may be necessary.

How does diabetic retinopathy cause vision loss?

Blood vessels damaged from diabetic retinopathy can cause vision loss in two ways:

Fluid can leak into the center of the macula, the part of the eye where sharp, straight-ahead vision occurs. The fluid makes the macula swell, blurring vision. This condition is called macular edema. It can occur at any stage of diabetic retinopathy, although it is more likely to occur as the disease progresses. About half of the people with proliferative retinopathy also have macular edema.

Fragile, abnormal blood vessels can develop and leak blood into the center of the eye, blurring vision. This is proliferative retinopathy and is the fourth and most advanced stage of the disease.

Does diabetic retinopathy have any symptoms?

Diabetic retinopathy often has no early warning signs. Don't wait for symptoms. Make sure to keep your appointments and see your retina specialist as directed.

What are the symptoms of proliferative retinopathy if bleeding occurs?

At first, you will see a few specks of blood, or spots, "floating" in your vision. If spots occur, you should call for an eye examination as soon as possible. You may need treatment before more serious bleeding occurs. Hemorrhages tend to happen more than once, often during sleep.

Sometimes, without treatment, the spots clear, and you will see better. However, bleeding can reoccur and cause severely blurred vision. For this reason you should call our office as soon as your vision becomes blurred so that we can schedule a dilated eye examination to see what is happening and arrange treatment.

If left untreated, proliferative retinopathy can cause severe vision loss and even blindness. Also, the earlier you receive treatment, the more likely treatment will be effective.
How are macular edema and diabetic retinopathy detected?

Macular edema and diabetic retinopathy are detected during a comprehensive eye exam that includes:

Visual acuity test. This eye chart test measures how well you see at various distances.

Dilated eye exam. Drops are placed in your eyes to widen, or dilate, the pupils. We use a special magnifying lens to examine your retina and optic nerve for signs of damage and other eye problems. After the exam, your close-up vision may remain blurred for several hours. You should be careful not to drive until your vision normalizes.

Tonometry. An instrument measures the pressure inside the eye. Numbing drops may be applied to your eye for this test.

We check your retina for early signs of the disease, including:

• Leaking blood vessels.
• Retinal swelling (macular edema).
• Pale, fatty deposits on the retina--signs of leaking blood vessels.
• Damaged nerve tissue.
• Any changes to the blood vessels or growth of new vessels.

If we believe you need treatment for macular edema, we may suggest a fluorescein angiogram. In this test, a special dye is injected into your arm. Pictures are taken as the dye passes through the blood vessels in your retina. The test allows us to identify any leaking blood vessels and guide treatment.

Macular Edema	Fluorescein angiogram showing leakage

How is a macular edema treated?

Macular edema is treated with laser. The procedure is called focal laser treatment. We find the small leaky blood vessels and spot weld them so they no longer leak. The procedure is not painful, although the laser light can be bright. It takes only a few minutes to do the procedure although it takes a few months for the eye to stop leaking. Often more than one treatment is needed to stop the leakage. New areas of leakage can develop or treated areas may start leaking again so continued follow up with your retina specialist is necessary.

Focal laser treatment helps to preserve vision. In fact, focal laser treatment reduces the risk of vision loss by 50 percent. It can also improve the vision in a certain percent of people.

In some severe cases injection of a steroid medication into your eye, and/or surgery may be required to lessen the edema.

How is diabetic retinopathy treated?

During the first three stages of diabetic retinopathy, no treatment is needed, unless you have macular edema. To prevent progression of diabetic retinopathy, people with diabetes should control their levels of blood sugar, blood pressure, and blood cholesterol. Daily exercise such as walking, biking or swimming can help your blood sugar. Weight loss and proper diet can also be very helpful.

Proliferative retinopathy is treated with peripheral laser. This procedure is called scatter laser treatment. Scatter laser treatment helps to shrink the abnormal blood vessels. As proliferative retinopathy can occur in many places, scatter laser requires more laser than focal laser. In fact, we may have to put in 1,000 to 2,000 laser spots in the areas of the retina away from the macula, causing the abnormal blood vessels to shrink. Because a high number of laser spots are necessary, three or more sessions usually are required to complete treatment. Although scatter laser may cause some loss of your side vision, color vision or night vision, it can also save the rest of your sight.

Scatter laser treatment works better before the fragile, new blood vessels have started to bleed. That is why it is important to have regular, comprehensive dilated eye exams. Even if bleeding has started, scatter laser treatment may still be possible, depending on the amount of bleeding. If the bleeding is severe, you may need a surgical procedure called a vitrectomy. During a vitrectomy, blood is removed from the vitreous of your eye.

What happens during laser treatment?

Both focal and scatter laser treatment are performed at our office or at the Royal Alexandra eye clinic. Before the laser, we will dilate your pupil and apply drops to freeze the front of the eye. The area behind your eye also may be frozen to prevent discomfort.

The lights in the office will be dim. As you sit facing the laser machine, we will hold a special lens to your eye to prevent the lid from closing. During the procedure, you may see flashes of light. These flashes eventually may create a stinging sensation that can be uncomfortable.

You will need someone to drive you home after laser. Because your pupil will remain dilated for a few hours, you should bring a pair of sunglasses.

For the rest of the day, your vision will probably be a little blurry. If your eye has increasing pain or you develop nausea or vomiting, you should call our office.

What is a vitrectomy?

If you have a lot of blood in the center of the eye (vitreous gel), you may need a vitrectomy to restore your sight. If you need vitrectomies in both eyes, they are usually done several weeks apart.

A vitrectomy is performed under either local or general anesthesia. Your doctor makes a tiny incision in your eye. Next, a small instrument is used to remove the vitreous gel that is clouded with blood. The vitreous gel is replaced with a salt solution. Because the vitreous gel is mostly water, you will notice no change between the salt solution and the original vitreous gel.

You will probably have to stay overnight after the vitrectomy. Your eye will be red and sensitive. You will need to wear an eye patch for a few days or 1 week to protect your eye. You also will need to use medicated eyedrops to protect against infection.

Are scatter laser treatment and vitrectomy effective in treating proliferative retinopathy?

Yes. Both treatments are very effective in reducing vision loss. People with proliferative retinopathy have less than a five percent chance of becoming blind within five years when they get timely and appropriate treatment. Although both treatments have high success rates, they do not cure diabetic retinopathy.

Once you have proliferative retinopathy, you always will be at risk for new bleeding. You may need treatment more than once to protect your sight.

What can I do if I already have lost some vision from diabetic retinopathy?

If you have lost some sight from diabetic retinopathy, ask us about low vision services and devices that may help you make the most of your remaining vision. We can help you get an appointment with the Canadian National Institute for the Blind (CNIB) or with the low vision services at the Royal Alexandra Hospital Eye Clinic.

What research is being done?

We are part of a number of research trials to improve the identification and treatment of diabetes and diabetic retinopathy. We are working with communities throughout Alberta to diagnose diabetic retinopathy by Tele-ophthalmology. The University of Alberta is the leader in Islet cell transplant research. New medications are being tested every day. We continue to support research that seeks better ways to detect, treat, and prevent vision loss in people with diabetes. This research is conducted through studies at the office or at the Royal Alexandra Hospital.

For example, researchers are studying drugs that may stop the retina from sending signals to the body to grow new blood vessels. Someday, these drugs may help people control their diabetic retinopathy and reduce the need for laser surgery.

What can I do to protect my vision?

You should have a comprehensive dilated eye exam at least once a year to determine if you have diabetic retinopathy. If you have diabetic retinopathy, you may need an eye exam more often. People with proliferative retinopathy can reduce their risk of blindness by 95 percent with timely treatment and appropriate follow-up care.

A major study has shown that better control of blood sugar levels slows the onset and progression of retinopathy. The people with diabetes who kept their blood sugar levels as close to normal as possible also had much less kidney and nerve disease. Better control also reduces the need for sight-saving laser surgery.

This level of blood sugar control may not be best for everyone, including some elderly patients, children under age 13, or people with heart disease. Be sure to ask your family doctor if such a control program is right for you.

Other studies have shown that controlling elevated blood pressure and cholesterol can reduce the risk of vision loss. Controlling these will help your overall health as well as help protect your vision.

What should I ask the staff at Alberta Retina Consultants?

You can protect yourself against vision loss by working in partnership with us. Ask questions and get the information you need to take care of yourself and your family.

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