Varicose veins are large, dilated veins just beneath the skin. Many avoid addressing them because they think they are just a cosmetic issue, but the truth is that they are often a result of a deeper health condition: superficial venous reflux disease. Your veins have one-way valves that close to prevent the blood from pooling at the ankles. When the valves are damaged or become stretched out, the blood pools and causes the veins to enlarge. This is what causes those puffy veins most often seen on the legs, calves, and ankles.