No one really knows the cause of spider veins, but it is assumed that heredity, local trauma, and hormonal levels are believed to be contributing factors. As you get older, you will be acquiring more spider veins and women are twice as likely as men to exhibit spider veins. Spider veins are formed by the dilation of the small veins under the surface of the skin, mostly on the legs. They look like red or purple sunbursts or web patterns. Spider veins are also referred to as telangiectasia or broken capillaries and they measure between 0.5 and 1 millimeter in diameter. On the face, spider veins are painless. Larger veins on the leg are known as varicose veins. Varicose veins are swollen or enlarged blood vessels caused by a weakening in the vein’s wall or valves. They are located somewhat deeper than spider veins, are sometimes raised, and often appear blue. These are treated with sclerotherapy and the smaller surrounding spider veins are treated with the ThermaVein technology.