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.
2.1.2 Unique Characteristics of Laser Light
By stimulating the emission of light from a laser, laser light has three unique characteristics that differentiate it from nonlaser light. The first of these characteristics is that laser light is monochromatic or composed of a single wavelength or color. The second unique characteristics a property known as coherence, where all the waves of light move together temporally and spatially as they travel together in phase with one another. The third characteristic is collimation, where the transmission of light occurs in parallel fashion without significant divergence, even over long distances
2.1.3 Irradiance and Energy Fluence
In order to use a laser to treat any skin condition, it is necessary to understand how the laser can be adjusted to obtain the most desired biologic effects in tissue (Fuller 1980). Two of the factors that are important in this process are irradiance (IR) and energy fluence (EF). Irradiance, also called power density, determines the ability of a laser toincise, vaporize or coagulate tissue and is expressed in watts/cm2. It can be calculated based on the formula:
IR= [laser output (watts) × 100] ÷ [pi × radius2 (of the laser beam)]
The energy fluence determines the amount of laser energy delivered in a single pulse and is expressed in joules/cm2. It can be calculated based on the formula:
EF = [laser output (watts) × exposure time (secs)] ÷ [pi × radius2 (of the laser beam)]
In the case of irradiance and energy fluence, the higher the number the greater the effect. For example, high irradiances are needed to incise tissue, while only low irradiances are needed to coagulate tissue.
2.1.4 How Does Laser Light Interact with Tissue?
In order to understand how to select the ideal laser from the myriad of currently available devices for the treatment of any cutaneous condition it is important to first understand how light produces a biologic effect in skin. The interaction of laser light with living tissue is generally a function of the wavelength of the laser system. In order for laser energy to produce any effect in skin it must first be absorbed. Absorption is the transformation of radiant energy (light) to a different form of energy (usually heat) by the specific interaction with tissue. If the light is reflected from the surface of the skin or transmitted completely through it without any absorption, then there will be no biologic effect. If the light is imprecisely absorbed by any target or chromophore in skin then the effect will also be imprecise. It is only when the light is highly absorbed by a specific component of skin that there will be a precise biologic effect. While this reaction may seem difficult to accurately anticipate, in fact, there are really only three main components of skin that absorb laser light: melanin, hemoglobin, and intracellular or extracellular water, and their absorption spectra have been well established. Manufacturers of lasers have taken this information and designed currently available technological devices that produce light which is the right color or wavelength to be precisely absorbed by one of these components of skin.
3.2.4 Advantages
The main advantage of nonablative wrinkle treatment is the relative lack of patient downtime in contrast to the obligatory 7–10 days of recovery time for ablative resurfacing. The devices that target dermal vasculature will help minimize, if not eliminate, the telangiectases frequently noted in patients with a history of significant sun exposure. Patients with diffuse erythema, resulting either from sun damage orrosacea, also note improvement. Devices which can target melanin as a potential chromophore, such as those with an IPL component, can also treat any concomitant pigmentary changes.Lentigines, melasma, and poikilo dermatous changes can be improved if not completely eradicated.
3.2.5 Disadvantages
The degree of wrinkle reduction is not as significant as that seen with the ablative devices and thus, patient dissatisfaction can be an issue. The improvement is often referred to as skin “toning”or “plumping up of the skin,” in contrast to the “tightening” often seen with ablative resurfacing. Appropriate patient education about the degree and unpredictability of enhancement is the key to success for these procedures. Good quality preoperative photography is helpful to document these changes as they can be subtle and improvement occurs over time, making the change less apparent.
3.2.6 The Future
The field of ablative resurfacing has remained stable with relatively few advances over the past 5 years. A notable exception to this has recently arisen with the advent of both plasma kinetic and fractional resurfacing. Although in their infancy, these novel resurfacing techniques show promise as we await the completion of long-term studies.
No The field of non ablative resurfacing has expanded dramatically over the past 8 years. Studies are underway to elucidate the best treatment intervals, compare the above techniques, and expand the energy potential of the given devices. In addition, a new 900-nm laser in conjunction with RF shows promise.
4 CONCLUSION:-
COCThe continual array of laser technology throughout the world has been nothing short of miraculous . Over the last fifteen years, this field has continued to grow and expand with the appearance of new technologies. Ablative and non-ablative laser resurfacing lead to improvement of photodamaged skin. Ablative laser resurfacing produces a significant wound, but long lasting clinical results. Non-ablative resurfacing is cosmetically elegant, but generally leads to subtle improvement only. Visible light non-ablative devices lead to a lessening of erythema and superficial pigmentary skin changes. Mid-infrared laser devices promote better skin quality and skin toning.
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