What is diabetic retinopathy?
Diabetic retinopathy is a disease of the retina caused by diabetes mellitus. In diabetes mellitus, the body is unable to metabolize sugar in the body. High blood sugar levels affect the tiny blood vessels to the retina by causing them to either become blocked or leaky. The result in the retina is leakage of fluid and protein, and ischemia due to insufficient oxygen and blood. Diabetic retinopathy is the fifth commonest cause of blindness worldwide.
Left: Normal vision. Right: Patchy central vision loss due to diabetic maculopathy.
Depending on the whether you have diabetic maculopathy or proliferative diabetic retinopathy, your vision can be affected in different ways. In maculopathy, your central vision will become affected. In proliferative retinopathy, your entire vision can be affected suddenly and dramatically. The visual impairment may or may not be reversed, depending on the type and severity of damage. This means that diabetes-related eye disease can cause blindness if not detected and treated early enough. And this is why diabetic retinopathy prevention is so important.
So is there anything you can do to protect your eyes from sight-threatening diabetic retinopathy?
Yes there is. There are certain risk factors for retinopathy that you can’t change, such as age, ethnicity and how long you’ve had diabetes for. However, there are other ways that you can reduce your risk. By adopting lifestyle measures that eliminate the modifiable risk factors for sight-threatening retinopathy, you reduce your chance of losing vision from diabetes. And you can do this by following 6 golden rules for diabetic retinopathy prevention.
Diabetic retinopathy prevention rule no. 1: Stop smoking
Smoking is a significant risk factor for many eye and general health problems. Eye conditions that can worsen with cigarette smoking include cataract, glaucoma and age-related macular degeneration. If you have diabetes and you smoke, you are more likely to develop nerve damage, kidney problems and cardiovascular disease.
Cigarette smoke contains many harmful chemicals, such as tobacco-specific N-nitrosamines (TSNAs), benzene, pesticides, arsenic, cadmium, cyanide, and many many more. These toxins circulate all around the body and cause oxidative damage to the macula and retinal blood vessels. This is bad news if you already suffer from diabetic maculopathy. In fact, this is also bad news if you have proliferative diabetic retinopathy because your retinal cells will become even more starved of oxygen and nutrients. Not only that, smoking also increases your blood pressure and raises your blood sugar level which makes it harder to control your diabetes.
If you smoke, do yourself a favour and stop, even if you do not have diabetes. This is one decision that you will never regret making. If you need help, ask your family doctor to help you quit.
Diabetic retinopathy prevention rule no. 2: Blood sugar
Tight blood glucose control is probably the most important factor in preventing diabetes-related complications, including diabetic retinopathy. Results from the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS), have conclusively shown that intensive control of blood glucose levels decreases the vascular complications from diabetes mellitus. Try to aim for a hemoglobin A1c level below 7%. The optimal level is less than 6.5%.
To do this, you have to make a firm commitment towards managing your diabetes. Controlling blood glucose levels requires discipline and perseverance. Make sure you take your medications and insulin injections as instructed by your doctor. You will also have to change your diet to a diabetes diet to reflect the changes in your glucose levels throughout the day (higher after meals and lower in between). You will need to coordinate what you eat and when you eat according to your blood sugar fingerprick test results. Increase your fiber intake while at the same time reduce your sugar and starch consumption. As a general rule of thumb, the foods you eat ought to have less than 5 g of sugar and more than 5 g of fiber.
Diabetic retinopathy prevention rule no. 3: Hypertension
If your blood pressure is well-controlled, then your chances of developing microvascular complications such as diabetic nephropathy and diabetic retinopathy decrease. When you have hypertension and your blood pressure is high, your heart becomes overworked. The American Diabetes Association and the National Institute of Health recommend a target blood pressure of below 130/80 mmHg. Exercise regularly, reduce your salt intake and cut down on processed foods. However, medications are often needed to control your blood pressure adequately. These include angiotensin converting enzyme inhibitors, angiotensin receptor blockers and beta blockers. The best medication for you will be the one that maintains your blood pressure at a reasonable level without causing you serious side effects.
Diabetic retinopathy prevention rule no. 4: Cholesterol
Likewise, if your cholesterol level is well-controlled, your chances of developing diabetes-related complications reduce. The recommended targets are triglyceride level of less than 150 mg/dL, a low density lipoprotein (LDL) cholesterol level of less than 100 mg/dL, and a high density lipoprotein (HDL) cholesterol level of more than 60 mg/dL. Eat more fish, grains and nuts while cutting down on red meats, saturated fats and junk food. Regular exercise helps. Sometimes, you may need medications to get your cholesterol level to the recommended level.
Two recent large multi-center diabetic retinopathy trials (FIELD and ACCORD) found that fenofibrate (a cholesterol lowering medication) reduced the need for retinal laser treatment for diabetic macular edema by 30 to 40%. Interestingly, the researchers felt that this effect was not due to the cholesterol lowering properties of fenofibrate. So if your cholesterol is high, it may be worthwhile considering taking fenofibrate for the dual benefit of lowering your cholesterol level and reducing your risk of diabetic laser treatment.
Diabetic retinopathy prevention rule no. 5: Exercise
Exercise is a part of the lifestyle factors are important in reducing the risk of diabetes-related complications. Regular exercise helps to control blood pressure, blood glucose and cholesterol levels. Any aerobic exercise will help you to maintain your weight and to keep your heart working well. In general, try to do about 30 minutes of aerobic exercise, such as brisk walking or swimming, at least a few days a week. If you’re just starting out, begin with less strenuous exercise for around 10 minutes. As your fitness improves, you can gradually increase the time and exertion level of your exercises.
Diabetic retinopathy prevention rule no. 6: Screening
Having diabetes does not necessarily mean that you will develop vision problems. The better your diabetes is controlled, the less likely you are to experience sight-threatening complications from diabetic retinopathy. The good thing is that most diabetic complications can be treated. The earlier treatment with retinal laser or intravitreal injections, the better your outcomes will be. Blindness can be prevented in up to 90% of those at risk if sight-threatening retinopathy is identified early enough and then treated appropriately.
The key in diabetic retinopathy prevention is early detection and treatment. Most developed countries now have an annual diabetic retinopathy screening service. When you attend for screening, your eyes will be dilated so that your retina can be examined thoroughly. Sometimes, a digital photograph is taken of your retina. This picture is then compared with previous pictures and examined for signs of sight-threatening retinopathy. Regular screening and eye examinations are absolutely essential because you may not be aware that there is anything wrong with your eyes until it is too late.