Laser surgery is surgery carried out using a laser beam. The high energy in an extremely narrow laser beam can burn through body tissues to make a fine "cut". The heat also seals blood vessels, so there is much less bleeding than when a knife is used. A less powerful laser beam can removed colored marks, such as tattoos, from the skin. Heat destroys the pigment because it absorbs much energy from the beam, whereas the surrounding skin is virtually unaffected, Surgeons also use lasers to treat some forms of skin cancer and eye problems.