photo credit: helgabj
As you should already know, high blood sugar levels can cause serious diabetic complications such as nerve damage, foot disease and chronic kidney disease. It can also increase the risk for heart attack and stroke significantly. But did you know that diabetes is the leading cause of adult blindness in the United States? Uncontrolled blood sugar levels creates a metabolic state that causes damage to the eye over time, eventually resulting in vision loss and blindness. Diabetes causes approximately 24,000 new cases of blindness every year in adult patients. It is for this reason, that it is essential for all diabetic patients to complete annual eye exams with a board certified ophthalmologist and to work hard to gain control of elevated blood glucose readings.
What is Diabetic Retinopathy?
Diabetic retinopathy is characterized by damage to the blood vessels and retina of the eyes of a patient with diabetes. This condition occurs in both type 1 and type 2 diabetics.
Diabetic retinopathy can be classified as one of the following:
- Nonproliferative diabetic retinopathy (NPDR)
- Proliferative diabetic retinopathy (PDR)
- Diabetic macular edema.
Nonproliferative Diabetic Retinopathy
Nonproliferative diabetic retinopathy is a complication of diabetes where damage to the retina occurs through the formation of small aneurysms, blood vessel changes, cotton wool spots and other abnormalities. This disorder does not consist of the formation of new blood vessels.
Most diabetic eye disease begins as mild nonproliferative diabetic retinopathy (NPDR) but may progress to more serious, sight threatening disease over time. Nonproliferative diabetic retinopathy can vary in severity from mild to very severe eye disease. Most patients with nonproliferative diabetic retinopathy have no symptoms. When a detailed eye exam is done the following may be seen:
- Mild Nonproliferative Diabetic Retinopathy: This condition is characterized by no visual changes and only small aneurysms seen in the retina.
- Moderate Nonproliferative Diabetic Retinopathy: Moderate NPDR is defined as having more noticeable changes on the dilated fundoscopic eye exam. These changes include multiple microaneurysms, cotton wool spots and tiny vascular changes.
- Severe Nonproliferative Diabetic Retinopathy: Patients with this type of eye disease will exhibit more severe changes on their eye exam that typically show changes in more than one area of the retina. To meet the criteria for severe nonproliferative diabetic retinopathy one of the following findings must be found on exam:
- More than 20 hemorrhages or aneurysm in all four areas of the retina
- Venous beading in two areas of the retina
- Changes in the veins in one area of the retina but no new blood vessel formation
- Very Severe Nonproliferative Diabetic Retinopathy: Patients are diagnosed with very severe nonproliferative diabetic retinopathy when the eye exam shows two or more of the above findings.
Proliferative Diabetic Retinopathy
Proliferative diabetic retinopathy occurs when new blood vessels and fibrous tissue grow on the optic disc and retina. These new vessels are fragile and can rupture easily creating bleeding within the eye. When this occurs, it can cause sudden and severe vision loss. The fibrous tissue acts as scar tissue and can cause tugging on the retina which can trigger a retinal detachment, another condition that results in sudden vision loss. Proliferative diabetic retinopathy is characterized as either early or high risk.
- Early Proliferative Diabetic Retinopathy: Patients with this type of eye disease have visible changes in the retina with new blood vessel formation but at this stage is not felt to be more severe. These vessels may grow on the optic disc (NVD) or they may be present on other parts of the retina (NVE).
- High Risk Proliferative Diabetic Retinopathy: Patients with this disorder should consider treatment using laser techniques called photocoagulation to reduce the risk of hemorrhage and vision loss. Patients are classified as high risk if they meet one of the following criteria:
- New blood vessel formation on the optic disc (NVD) that occupy more than 1/4 of the optic disc.
- New vessel formation on the optic disc (NVD) that has ruptured causing hemorrhage within the eye.
- Blood vessel growth anywhere on the retina (NVE) that is larger than 1/2 of the optic disc in diameter and has ruptured, causing hemorrhage within the eye.
Diabetic Macular Edema (DME)
Diabetic macular edema is a condition where fluid leaks from the blood vessels within the retina causing swelling of the macula, which is needed for the ability to distinguish colors and fine details. This complication can occur with both nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). When the swelling affects the center of the macula of the eye, it is diagnosed as climically significant macular edema and treatment with laser photocoagulation is recommended. Diabetic macular edema can also be classified as mild, moderate or severe.
Who Is At Risk For Developing Diabetic Retinopathy?
All patients with diabetes are at risk for developing diabetic retinopathy. This is why it is recommended that all patients with type 1 diabetes begin having annual eye exams starting 3-5 years after diagnosis. Patients with type 2 diabetes should start eye exams immediately after diagnosis because it is likely that blood sugar levels have been elevated for several years before the diagnosis was confirmed. Your risk of developing this serious complication of diabetes is increased if you have the following risk factors:
- Poor control of diabetes
- Been diabetic for many years
- High blood pressure
- Chronic kidney disease
- High cholesterol
- Central obesity
- Cataract surgery
- Pregnancy: Pregnancy can trigger rapid progression of diabetic eye disease. All women should have a dilated eye exam prior to getting pregnant and again during each trimester and 6-8 weeks post-partum.
Diabetic Retinopathy Treatment
Most severe manifestations of diabetic eye disease are treated using laser photocoagulation therapy to prevent fluid leakage and hemorrhage from blood vessels. Early intervention is important to prevent permenent vision loss.
Diabetes & Your Eyes: Other Ways That Diabetes Affects The Eye
Diabetes affects the eyes in many ways, causing damage to multiple areas. Patients with diabetes are also at higher risk for developing multiple eye conditions such as:
- Glaucoma: All diabetic patients should be screened for glaucoma at their annual eye exams.
- Cataracts: Cataracts are very common in the general population but are also found more frequently in patients with diabetes.
- Vision changes: Blurring of the vision is very common in uncontrolled diabetes, especially immediately after diagnosis when sugars are being adjusted to improve blood glucose levels. Typically these changes will stabilize within 1-2 months after the initiation of treatment.
- Rubeosis iridis: This is similar to proliferative diabetic retinopathy only new blood vessels form on the iris of the eye.
- Nerve damage: High blood sugar levels can affect the nerves that control eye movement.
If you have diabetes and want to keep your vision, it is very important that you follow your doctor’s instructions and get your sugars under control. By far, this has the greatest impact on the development and progression of diabetic retinopathy. By taking control of your diabetes, you can reduce your risk of eye complications, vision loss or complete blindness. Don’t forget to get screened every year because diabetic retinopathy often has no symptoms until it is too late!