Our eyes have been called "the window to our soul." It turns out, they also are often a very effective window to our overall health. During a comprehensive eye exam, your eye doctor can observe and evaluate the health and condition of the blood vessels in your retina, which are a good predictor of the health of blood vessels throughout your body. Conditions such as diabetes, hypertension and hypercholesterolemia all are visible by changes in the appearance of the retinal blood supply and blood vessels. Annual eye exams are especially important for anyone with diabetes or who might be at risk for the disease (due to obesity, family history or other reasons). More than 30 million Americans with diabetes and another 84 million who have prediabetes are at risk for developing diabetic eye disease, the leading cause of blindness among adults. In its early stages, diabetic eye disease has no visible symptoms; only a comprehensive eye exam can detect signs of the disease so treatment can begin soon enough to prevent vision loss.