Save your eyes with exercise

Philip J. Goscienski, M.D.

May 2008

Hundreds of thousands of blind and near-blind Americans would enjoy watching television, reading books and basking in the smiles of their grandchildren if only they had exercised more. An exaggeration? Not at all! But the link is not obvious.

Diabetes is rapidly gaining on Age-related Macular Degeneration (AMD) as the leading cause of blindness in the United States. Among persons between the ages of 20 and 74, eye damage resulting from diabetes has become the leading cause of vision loss.

Diabetic retinopathy refers to progressive damage to the retina, the lining of the back part of the eye. The high blood sugar that is the hallmark of diabetes weakens and scars the eye's blood vessels. That gradually eliminates the retina's ability to receive images and transmit them to the brain.

There is no cure for diabetic retinopathy. By the time diabetes is diagnosed nearly one half of its victims already have suffered some eye damage. Estimates of new cases of blindness each year are climbing because type 2 diabetes is on a dramatic upswing in all developed countries. What is even more ominous is the recent surge in diabetes among children, who appear to develop complications, including blindness, earlier than adults do.

Physical activity can prevent diabetes, even in persons who have a familial or genetic predisposition to it. Though poor diet is a major contributor to the disease, regular, moderately intense daily exercise will postpone or prevent it. Among persons with prediabetes, the earliest identifiable stage of type 2 diabetes, those who walk at a moderate pace for about 4 hours a week can lower their risk of full-blown disease by more than 50 percent.

Type 2 diabetes is extremely rare among population groups whose relatively primitive lifestyle requires a high level of physical exertion. The classic example is the Pima Indian population of central Mexico. These farmers and laborers have almost no modern tools or machinery. They also have almost no type 2 diabetes, high blood pressure, heart disease or osteoporosis. Among their genetically identical but sedentary counterparts in the American Southwest, type 2 diabetes is a major cause of death and disability, including blindness.

How much physical activity do you need? Whatever it takes to keep body weight in the normal range. That's about 30 to 60 minutes on most days of the week. The kind of exercise doesn't matter but it should include weight-bearing exercise, using free weights or weight machines 2 or 3 days a week. Such resistance exercise improves the way in which the body uses insulin, further lowering the risk of type 2 diabetes.

It would be naïve to think that diet is not important in the prevention of type 2 diabetes. A diet that is made up primarily of fruits, vegetables and whole grains protects against type 2 diabetes as well as against obesity and heart disease. Eliminate foods that cause rapid, high levels of blood sugar, such as refined baked goods and sweets. An occasional treat of this type is reasonable. A daily dose of junk food is a recipe for chronic disease and a shorter lifespan that even daily exercise may not protect you from.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.