Laser surgery is a type of surgery that uses a laser (in contrast to using a scalpel) to cut tissue. Laser surgery is a type of surgery that uses a laser (in contrast to using a scalpel) to cut tissue. Examples include the use of a laser scalpel in otherwise conventional surgery, and soft-tissue laser surgery, in which the laser beam vaporizes soft tissue with high water content. Laser surgery is commonly used on the eye. Techniques used include LASIK, which is used to correct near and far-sightedness in vision, and photorefractive keratectomy, a procedure which permanently reshapes the cornea using an excimer laser to remove a small amount of the human tissue. Types of surgical lasers include carbon dioxide, argon, Nd:YAG laser, and potassium titanyl phosphate, from among others. Surgical laser systems, sometimes called 'laser scalpels', are differentiated not only by the wavelength, but also by the light delivery system: flexible fiber or articulated arm, as well as by other factors. CO2 lasers were the dominant soft-tissue surgical lasers as of 2010. Soft-tissue laser surgery is used in a variety of applications in human (general surgery, neurosurgery, ENT, dentistry, orthodontics, and oral and maxillofacial surgery as well as veterinary surgical fields. The primary uses of lasers in soft tissue surgery is to cut, ablate, vaporize, and coagulate. There are several different laser wavelengths used in soft tissue surgery. Different laser wavelengths and device settings (such as pulse duration and power) produce different effects on the tissue. Some commonly used lasers types in soft tissue surgery include erbium, diode, and CO2. Erbium lasers are excellent cutters, but provide minimal hemostasis. Diode lasers (hot tip) provide excellent hemostasis, but are slow cutters. CO2 lasers are both efficient at cutting and coagulating. A range of lasers such as erbium, dye, Q switch lasers and CO2 are used to treat various skin conditions including scars, vascular and pigmented lesions, and for photorejuvenation. The laser surgery for dermatology often bypass the skin surface. The principle of laser surgery for dermatologic problem is based on SPTL (selective photothermolysis). The laser beam penetrates the skin until it encounters chromophore which absorbs the laser beam. After absorption of the laser beam, heat is generated to induce coagulation, necrosis of the targeted tissue, this results in removal of unwanted tissue by laser surgery. Laser resurfacing is a technique in which covalent bonds of a material are dissolved by a laser, a technique invented by aesthetic plastic surgeon Thomas L. Roberts, III using CO2 lasers in the 1990s.