Veins are the blood vessels that return blood to the heart from the body. To overcome the force of gravity, inside the veins are one-way valves which open to allow blood flow to the heart, and close to prevent "reflux" of blood back to the body. When these valves fail to function, or if the vein is damaged so the valves do not completely close, blood can begin to pool in the vein and cause a variety of vein complications.
What are the different types of vein disease?
Spider veins are the small, thread-like colored veins that are most often seen on the surface of the skin. While many people seek treatment for spider veins for cosmetic reasons, spider veins also can result in substantial discomfort requiring therapy.