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1.0 ABSTRACT
Facial laser resurfacing uses high-energy, pulsed and scanned lasers. Pulsed CO2 and Erbium: YAG lasers have been successful in reducing and removing facial wrinkles, acne scars and sun-damaged skin. High-energy, pulsed, and scanned CO2 laser is generally considered the gold standard against which all other facial rejuvenation systems are compared. Typically a 50% improvement is found in patients receiving CO2 laser treatment. Side effects of treatment include post-operative tenderness, redness, swelling and scarring. The redness and tenderness last several weeks, while new skin grows over the area where the damaged skin has been removed by the laser treatments (ablative laser systems). Secondary skin infection including reactivation of herpes is also a potential problem until healing occurs. Extreme caution is needed when treating darker skinned individuals as permanent loss or variable pigmentation may occur long term.
Erbium: YAG produces similar results and side effects compared to CO2. Despite their side effect profile and long recovery time these ablative laser systems, when used properly, can produce excellent results. Recently non-ablative lasers have been used for dermal modeling; 'non-ablative' refers to heating up the dermal collagen while avoiding damage to the surface skin cells (epidermis) by cooling it. Multiple treatments are required to smooth the skin.
1.1 INTRODUCTION
One of the most popular anti-aging remedies is laser skin resurfacing, which improves the appearance of fine lines or wrinkles, scars and hyperpigmentation (discolored areas of the skin), primarily around the eyes and mouth. It can also be used to treat large areas of the face.Dr.Goldman has been called the “Father of Lasers in Medicine and surgery”. Laser skin resurfacing holds advantages over alternative approaches that may cause discomfort, bleeding and bruising, all of which equate to a longer recovery time. What's more, today's lasers are gentler and safer than they have been in the past.
All skin treatments work in a similar manner. They remove a layer of skin so that the new skin can flourish and fill in the wrinkles and crevices. Until recently, the only options to medically treat damaged skin were chemical peels and dermabrasion, which is more invasive and far less gentle than microdermabrasion. During dermabrasion, the surgeon uses a wire brush or a diamond wheel with rough edges to remove the upper layers of the skin. This process wounds the skin and causes it to bleed. As the wound heals, new skin grows to replace the damaged skin. These procedures do offer the anti-aging benefits of glowing skin, reduced wrinkles, decreased areas of skin discoloration and minimal scarring, but they do not produce predictable results. By contrast, laser skin resurfacing uses laser light to target the superficial and deep layers of the skin.
2.1 LASER
The word “LASER” is an acronym that stands for Light Amplification by the Stimulated Emission of Radiation. For this reason, a laser is not just an instrument but also a physical process of amplification. All lasers are composed of the same four primary components. These include the laser medium (usually a solid, liquid, or gas), the optical cavity or resonator which surrounds the laser medium and contains the amplification process, the power supply or “pump” that excites the atoms and creates population inversion, and a delivery system (usually a fiber optic or articulating arm with mirrored joints) to precisely deliver the light to the target.
Lasers are usually named for the medium contained within their optical cavity
The gas lasers consist of the argon, excimers, copper vapor, helium-neon, krypton, and carbon dioxide devices. One of the most common liquid lasers contain fluid with rhodamine dye and is used in the pulsed dye laser. The solid lasers are represented by the ruby, neodymium: yttrium-aluminum-garnet (Nd: YAG), alexandrite, erbium, and diode lasers. All of these devices are used to clinically treat a wide variety of conditions and disorders based on their wavelength, nature of their pulse, and energy.
The excitation mechanism can be accomplished by direct electrical current, optical stimulation by another laser (argon), radiofrequency excitation, white light from a flash lamp, or even (rarely) chemical reactions that either make or break chemical bonds to release energy, as in the hydrogen-fluoride laser.
2.1.1 Laser Emission
All atoms are composed of a central nucleus surrounded by electrons that occupy discrete energy levels or orbits around the nucleus and give the atom a stable configuration. When an atom spontaneously absorbs a photon of light, the outer orbital electrons briefly move to a higher energy orbit, which is an unstable configuration . This configuration is very evanescent and the atom quickly releases a photon of light spontaneously so the electrons can return to their normal, lower energy, but stable inner orbital .Under normal circumstances, this spontaneous absorption and release of light occurs in a disorganized and random fashion and results in the production of incoherent light.
When an external source of energy is supplied to a laser cavity containing the laser medium, usually in the form of electricity, light, microwaves, or even a chemical reaction, the resting atoms are stimulated to drive their electrons to unstable, higher energy, outer orbits. When more atoms exist in this unstable high energy configuration than in their usual resting configuration, a condition known as population inversion is created, which is necessary for the subsequent step in light amplification of light occurs in the optical cavity or resonator of the laser. The resonator typically consists of an enclosed cavity that allows the emitted photons of light to reflect back and forth from one mirrored end of the chamber to the other many times until a sufficient intensity has been developed for complete amplification to occur. Through a complex processor of absorption and emission of photons of energy, the prerequisite for the development of a laser beam of light has been met and amplification occurs. The photons are then allowed to escape through a small perforation in the partially reflective mirror. The emerging beam of light has three unique characteristics that allow it to be delivered to the appropriate target by fiber optics or an articulated arm.