Protecting your eyesight is one of the most important things you can do to help maintain your quality of life. Some type of sight-threatening eye problem affects one in six adults age 45 and older. And the risk for vision loss only increases with age. Since the leading causes of blindness and low vision are primarily age-related diseases such as macular degeneration, cataract, diabetic retinopathy and glaucoma, protecting your eyesight as you age is an essential part of your health care.   How the Eye Works In a number of ways, the human eye works much like a digital camera: Light is focused primarily by the cornea —...