MODEL RELEASED. Laser thread vein treatment. Surgeon using a laser tool to remove thread veins from a female patient's leg. Thread or spider veins are dilated capillaries in the skin. They most often form on the cheeks, nose and legs. They are not dangerous, but many people wish to have them removed for cosmetic reasons. The laser operator focuses a low-energy laser beam (green) through a pen-like tool onto the patient's skin. The heat from the laser is absorbed by the blood vessels, causing the blood to coagulate and be broken down by the surrounding cells.