A thread vein is a small visible red or purple blood vessel near the surface of the skin blood contains haemoglobin the red pigment in the blood that absorbs the light and converts it into heat the heat destroys the protein in the wall of the thread vein as a result the vein will gradually and safely disappear through lymphatic system the number of treatments depends on the severity of the thread vein clinical studies have confirmed that 1 4 treatments usually are needed and these are ti