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Disease

Diabetic Retinopathy

Definition: Diabetic retinopathy is the most common diabetic eye disease and a leading cause of blindness in American adults. If you have diabetes mellitus, your body does not use and store sugar properly. High blood-sugar levels can damage blood vessels in the retina, the nerve layer at the back of the eye that senses light and helps to send images to the brain. The damage to retinal vessels is referred to as diabetic retinopathy.
In some people with diabetic retinopathy, blood vessels may swell and leak fluid. In other people, abnormal new blood vessels grow on the surface of the retina. The retina is 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 not notice changes to your vision. But over time, diabetic retinopathy can get worse and cause vision loss. Diabetic retinopathy usually affects both eyes.

Causes and Risk Factors:
If you have diabetes, your body doesn't use sugar (glucose) properly. Sugar in your blood is vital to your health because it's a main source of energy for your body's cells. But too much sugar in your blood can cause damage throughout your body, including your kidneys, nerves, heart and eyes. Damage to the capillaries in your eyes occurs in diabetic retinopathy.
Approximately 40 percent of all people with diabetes have at least mild diabetic retinopathy. About 3 percent suffer severe visual loss because of this disease. In general, the longer one has had diabetes, the greater are one's chances of developing diabetic retinopathy. Diabetic retinopathy generally takes at least eight years to develop in juvenile onset diabetes, but may be present at the time adult onset diabetes is first diagnosed. High blood pressure and high cholesterol in the blood are additional risk factors that your doctor will address.

Self-monitoring of blood glucose at home is very important.  Regular testing tells you how well diet, medication, and exercise are working together to control your diabetes.  Another test that is equally as important is called an A1c (also referred to as a hemoglobin A1c) which is done at your doctor’s office.  The A1c test is used primarily to monitor the glucose control of diabetics over time. The goal of those with diabetes is to keep their blood glucose levels as close to normal as possible. This helps to minimize the complications caused by chronically elevated glucose levels, such as progressive damage to body organs like the kidneys, eyes, cardiovascular system, and nerves. The A1c test gives a picture of the average amount of glucose in the blood over the last few months. It can help a patient and his doctor know if the measures they are taking to control the patient’s diabetes are successful or need to be adjusted.
Patients with diabetes are also at greater risk for other eye diseases such as cataract and glaucoma. Your doctor will include evaluation for these problems in your examination.

Stages of Diabetic Retinopathy:

Mild Nonproliferative Retinopathy (Background Diabetic Retinopathy or BDR). 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.

Signs & Symptoms:
One of the first symptoms of diabetic retinopathy is poor night vision. Other symptoms include:

• "Floaters" (spots in front of one's eyes)
• Blurred vision
• Blindness

However, many people have no symptoms before major bleeding occurs in the eye. This is why everyone with diabetes should have regular eye exams.

Diagnostic Testing:  Diabetic retinopathy is diagnosed by looking at the retinas using an illuminating instrument called an ophthalmoscope that is designed for inspecting the inside of the eye. The appearance of the condition is quite characteristic - there are yellow patches of fatty deposition, tiny dark dots called microaneurysms and the growth of fronds of new blood vessels.

If severe bleeding has occurred, the retina may not be visible, but the blood can be seen and the diagnosis can be made from the knowledge that the patient is diabetic.
As part of an eye examination, your doctor may include diagnostic procedures such as  fluorescein angiography and optical coherence tomography to identify leaking blood vessels.

Treatment: If you have mild nonproliferative diabetic retinopathy, you may not require treatment right away. However, your eye doctor will want to monitor your retina. Proliferative diabetic retinopathy sometimes requires prompt surgical treatment.
The main treatments for diabetic retinopathy are photocoagulation, vitrectomy and injections of medicines. In many cases, these treatments are effective and slow or stop the progression of the disease for some time. But they're not a cure. Because diabetes continues to affect your body, you may experience further retinal damage and vision loss at a later time.

Your doctor may recommend photocoagulation if you have:

• Diabetic macular edema, a swelling that involves or threatens the center of the retina
• Severe nonproliferative diabetic retinopathy, especially if you have type 2 diabetes
• Proliferative diabetic retinopathy
• Neovascular glaucoma

A vitreous hemorrhage may clear up on its own. But if the hemorrhage is massive and doesn't clear, a vitrectomy may help to restore your sight and may allow the application of needed laser treatment.

Prevention:

• Control your blood sugar
• Keep an eye on vision changes
• Keep your blood pressure down
• Control your cholesterol
• Stop smoking
• Control stress