The first laser (LASER is an abbreviation of the EnglishLight Amplificationby Stimulated Emissionof Radiation: light amplification using induced (stimulated) radiation)for cosmetic purposes (in ruby) was designed and tested very recently, just 55 years ago, in 1960. Since then, laser cosmetology has been one of the most demanded areas in aesthetic medicine.
Laser devices are used with great success for epilation, rejuvenation, lifting, removal of blood vessels, age spots, scars, stretch marks, post-acne, neoplasms, tattoos, for the treatment of vitiligo, psoriasis, acne (acne), ingrown nails.
Today's review of laser equipment is highly specialized: we will acquaint readers in detail with devices for skin rejuvenation.
The laser consists of three main elements:
- energy source (or "pumping" mechanism);
- working body (active environment);
- mirror system (optical resonator).
The energy sourcecan be an electric discharge, a flash lamp, an arc lamp, another laser, a chemical reaction, etc. , which activate the working medium with their energy.
Working fluidis the main determining factor of the generated wavelength, as well as other laser properties (monochrome, coherence, narrow focus). There are hundreds or even thousands of different working bodies on the basis of which a laser can be built. However, the following working media are most often used: liquid (consists of an organic solvent, for example, methanol, ethanol or ethylene glycol, in which chemical dyes are dissolved), gases (a mixture of gases, for example: carbon dioxide, argon, krypton or mixtures such as in heliumneon lasers; these lasers are most often pumped by electrical discharges), solids (such as crystals and glass; solid materials are usually activated by the addition of small amounts of chromium, neodymium, erbium, or titanium ions); semiconductors.
So, according to the type of working medium (active medium), lasers are divided into:
- liquid (on inorganic or organic dyes);
- metal vapor lasers;
- solid (crystals, glass);
- semiconductor (or diode).
Optical resonator, the simplest form of which are two parallel mirrors, is located around the working body of the laser. Forced radiation of the working medium is reflected between the mirrors and back into the working medium, accumulating energy. The wave can be reflected many times before it comes out. In more complex lasers, four or more mirrors are used, which also form an optical resonator, but of a more complex design.
The quality of manufacture and installation of these mirrors is one of the most important conditions for the quality of a laser system.
Also in the laser system, additional devices can be mounted to obtain various effects, such as rotating mirrors, modulators, filters and absorbers. Their use allows changing the parameters of laser radiation, for example, wavelength, pulse duration, etc.
TECHNICAL PARAMETERS OF LASER EQUIPMENT
Laser energy parameters:
- Power, measured in watts (W).
- Energy, measured in joules (J).
- Energy density (J / cm2).
- Pulse duration, measured in milli-, nano-, picoseconds.
- Wavelength, measured in micrometers (μm) and nanometers (nm).
Laser radiation, acting on a living organism, is subject to the phenomena of reflection, absorption, scattering. The degree of these processes depends on the condition of the skin: moisture, pigmentation, blood circulation, swelling of the skin and underlying tissues.
Many lasers target specific chromophores, which are biological structures with a well-defined absorption spectrum. The ability of a chromophore to absorb light of different wavelengths with different intensities is determined by the absorption spectrum. The unit of measure for the ability of a chromophore to absorb laser light is the absorption coefficient.
The absorption spectra of different chromophores differ radically. Therefore, it is important that the wavelength of the laser radiation coincides with the wavelength at the peak of the absorption capacity of the chromophore that is planned to be exposed.
Therefore, there is no one universal wavelength, that is, one laser, for all indications (assignments). So, a laser for hair removal cannot rejuvenate the skin, and vice versa. Of course, quite often it happens that several purposes are indicated in the laser instructions, but in fact there will be only one problem effectively solving such equipment.
The penetration depth of laser radiation is inversely proportional to the absorption coefficient and, as a consequence, depends on the wavelength. For different chromophores of the skin (water, melanin, hemoglobin, oxyhemoglobin), the depth of penetration is also different. For example, in the visible region (0. 38-0. 74 microns, or 380-740 nm), the penetration depth will be 3-7 mm, in the infrared region (0. 76-1. 5 microns) - from 0. 5 to 1, 5 mm, and in the ultraviolet region (0. 3-0. 5 microns), laser radiation is strongly absorbed by the epidermis and therefore penetrates into tissues to a shallow depth, from 0. 2 to 0. 4 mm.
METHOD OF LASER RADIATION GENERATION
There arepulsed and cw lasersgenerating radiation. Depending on the pumping method, continuous and pulsed generation of laser radiation can be obtained. Pulsed light is generated as beams of waves that are interrupted for a specified period of time. Other lasers generate continuous light, and a special device splits this light into short segments. As a rule, lasers of continuous generated radiation, in addition to physiotherapy lasers, have the property of unwanted heat generation at the site of exposure, which can lead to scar changes and damage to the tissues surrounding the site of exposure.
LASER POWER LEVEL
The radiation power of medical (in particular, cosmetic) lasers varies within wide limits, determined by the purposes of their application. For lasers with continuous pumping, the power can vary from 0. 01 to 100 W. Pulsed lasers are characterized by pulse power and pulse duration. The power of pulsed lasers is several orders of magnitude higher. Thus, a neodymium laser generates a pulse with an energy of E = 75 J, the duration of which is t = 3x10-12 s. Pulse power: P = E / t = 2. 5x1013 W (for comparison: the power of the hydroelectric power station is approximately 109 W).
In cosmetology practice, including for skin rejuvenation procedures, laser radiation is used both with a low power value (low-intensity laser radiation, LILI) and high (high-intensity laser radiation, VILI).
LOW INTENSITY LASER RADIATION (LLLT)
The action of LLLT is to activate enzymes of cell membranes and stabilize lipids. It is known that LLLT stimulates cell division and development. The effect occurs at a subtle, atomic-molecular level, where energy is absorbed under the influence of laser radiation of a certain frequency (as a rule, in the red and infrared ranges). Such energy absorption leads to a sharp increase in the intracellular concentration of Ca2 +, that is, there is an activation of the accumulation and release of ATP, the restoration of cell membranes, an increase in intracellular metabolism and an increase in regenerative processes due to the activation of cell proliferation (division). Old cells are intensively replaced with new ones, and the biorhythm of this process is restored. The therapy uses low-intensity lasers (with an intensity of 0. 1-10 W / cm2). The maximum wavelength for therapeutic lasers is 1300 nm. In particular, diode lasers are used for skin rejuvenation procedures:
- emitters with wavelengths of 890 nm and 915 nm (laser rejuvenation);
- low-intensity laser with a wavelength from 785 to 890 nm (laser biorevitalization and laser mesotherapy - delivery of active ingredients to the skin through LLLT).
Treatments with therapeutic lasers are painless and comfortable for the patient due to their low intensity. In some cases, you may feel a slight warmth. There is no rehabilitation period, however, in order to obtain any pronounced effect (improving the elasticity and firmness of the skin, microrelief, moisturizing and lifting the skin), a course of procedures and supportive procedures is required.
The basic set of therapeutic lasers includes a device combined with a control panel (sometimes in the form of a touchscreen display) and a handpiece-emitter. The kit may include several emitters (for example, with a large working surface area for working on the body and with a small area for working on the face), as well as attachments for various procedures. Therapeutic lasers have small dimensions, low power consumption and the ability to install the working medium directly in the handpiece, without using a light guide tool to deliver radiation.
HIGH INTENSITY LASER RADIATION (WHILE)
High-intensity laser radiation (2500 J / cm2) allows to concentrate considerable energy in a small volume, which causes local thermal heating, rapid evaporation, and hydrodynamic explosion in a biological environment. In cosmetology, VILI has the widest application, one of which is skin rejuvenation.
Skin rejuvenation using high-intensity laser radiation is a modern method of lifting, removing and / or reducing the depth of wrinkles, and improving the quality of the skin. For high-intensity laser rejuvenation, those devices are used, the radiation of which is well absorbed by water (since the skin is 77 percent water). The purpose of using such lasers is a rapid rise in temperature in the region of absorption of a laser pulse with instantaneous evaporation of tissue.
Among the variety of high-intensity laser equipment for skin rejuvenation, it is customary for specialists to distinguish two main types of devices: fornon-ablativeandablative method.
Ablation - evaporation of superficial tissues by means of laser exposure.
Laser ablative devicesare extremely effective in the fight against age-related changes in the skin: the degradation of collagen and elastin - the structural proteins of the skin that provide it with firmness and elasticity. Traumatic laser treatments are applied to trigger the renewal processes. Moreover, it should be noted that the stronger the injury, the more powerful the rejuvenating effect, but at the same time, of course, the longer the rehabilitation period and the higher the risk of side effects.
That is why the main tendencies in the development of modern lasers for skin rejuvenation are a search for a compromise, an attempt to find a way to minimize trauma to the skin, but at the same time get a powerful response to a regenerative response.
Modern ablative devices include:
- fractional CO2 lasers (carbon dioxide lasers);
- fractional erbium YAG lasers (solid-state yttrium-aluminum-garnet crystal laser with erbium ions).
It is necessary to clarify the term “factional” right away.
A fractional laser differs from a conventional laser in that the laser beam is forcibly divided into a multitude of microbeams ("fractions"). This can be implemented in hardware in several ways:
- with the help of microlenses installed in the handpiece (a large number of beams simultaneously hit the skin);
- in scanner mode, when one laser beam sequentially perforates the skin;
- with a roller attachment, which is controlled by laser pulses and allows the procedure to be carried out in motion.
This leads to the fact that the laser effect on a particular area of the skin becomes not total, but zonal: not the entire surface of the skin is exposed to the effect, but thousands of its micro-areas, between which the unaffected tissue remains. Fractional lasers are less traumatic: at the time of tissue processing, they do not cover the entire surface of the skin, but from 3 to 70 percent, depending on the laser settings, while triggering the recovery mechanism throughout the entire area.
In fact, thanks to the advent of fractional lasers, a new era of laser cosmetology began: laser procedures have become less painful, safer ("delicate"), the rehabilitation period after procedures has been significantly reduced (from two days to one week). At the same time, the clinical effectiveness did not decrease, but, on the contrary, increased.
Modern carbon dioxide lasersoperate on the principle offractional photothermolysis, which consists in the formation of coagulation microzones in the form of columns perpendicular to the skin surface. The term "photothermolysis" here means destruction of tissue under the influence of temperature, which arose in the process of transferring laser radiation energy to tissue (photo - light, thermal - heating, lysis - destruction). The carbon dioxide laser has a radiation wavelength of 10. 6 microns. When carrying out the procedure of fractional rejuvenation, this laser removes microzones of the skin practically at the entire depth of the epidermis (up to 20 microns), while the zone of thermal damage extends into the dermis by 150 microns or more, causing collagen coagulation. This leads to the desired effect (reduction of denatured collagen fibers, smoothing of the skin).
There are a number of fractional carbon dioxide devices on the market today with adjustable flux density and pulse duration. This allows you to select the temperature and depth of heating of the dermis. Thanks to new technologies, the time for a complete post-procedural recovery has been reduced to one week. Firms - distributors of modern carbon dioxide lasers began to advertise the procedures carried out with their help as procedures for the rejuvenation of the "weekend", since when conducting fractional laser photothermolysis, the "acute" rehabilitation period (intense edema and erythema) passes in two days off and on Monday the patientcan go to work.
Erbium laser has a wavelength of 2. 94 microns and a much higher absorption coefficient than a carbon dioxide laser. Erbium laser radiation penetrates to a depth of about 1 micron, causing rapid vaporization of a thin layer of the epidermis with virtually no damage to the surrounding tissues.
“Erbium laser (Er: YAG) is a typical ablative laser. The ablation effect is so pronounced that the upper layer of the epidermis instantly evaporates without leaving any traces. This laser is well suited for resurfacing, smoothing scars, removing pigmentation. "
Today, erbium lasers are actively used when working with the most sensitive areas: neck and decollete, paraorbital and periorbital areas. With this laser, each point can be processed several times, while the doctor has the ability to control the entire process of "grinding". It is erbium lasers that are actively used intraoperatively by plastic surgeons. Also, erbium lasers are preferred when the patient is not ready for long-term rehabilitation.
Non-ablative high-intensity lasersdo not work on the principle of evaporation, but on the principle of heating water and coagulation with the formation of new collagen in the affected areas.
To implement the non-ablative method, as a rule, a laser with a large penetration depth into the tissue is chosen. In this category, for rejuvenation, theneodymium (Nd: YAG) laser(yttrium-aluminum-garnet crystal doped with neodymium) with a wavelength of 1064 nm, which corresponds to the near-infrared spectrum, is mainly used.
The radiation of such a laser can penetrate into the dermis to a depth of 5 mm. For the purpose of skin rejuvenation, this laser is usually used in the millisecond and nanosecond range of pulses, which allows stimulating collagen synthesis (in almost all cases) without damaging the surrounding tissues, that is, in a non-ablative mode. But when focusing in a small spot, it can also be used for ablation.
In modern cosmetology, neodymium laser is used primarily for removing unwanted vessels, for example, spider veins, but also for photorejuvenation. The technique even has a separate name -non-ablative dermal remodeling. In this case, the object of influence is hemoglobin. The purpose of the action is to stimulate collagen growth. Heat is generated where the laser radiation is most absorbed, such as the upper papillary layer, and spreads to nearby tissues. The consequence is a predictable inflammatory response causing changes in dermal collagen synthesis with a concomitant effect of skin renewal. Thus, due to partial coagulation of the microvascular bed and partial denaturation of the collagen structure, the laser triggers the formation of young fibroblasts.
I would especially like to note the latest developments in the field of laser technologies for skin rejuvenation - the emergence of picosecond lasers.
“In 2015, the central theme of all major international conferences on laser medicine was the use of picosecond lasers for rejuvenation. This is a completely new and promising technology that only appeared in 2014 and received FDA approval. The principle of operation of picosecond lasers goes beyond the theory of selective photothermolysis, since they affect the tissue not through heating (thermolysis), but through instantaneous oversaturation of the target with energy ”.
The picosecond laser generates pulses, the duration of which is measured in trillionths of a second. Such short pulses do not have time to inflict thermal damage on tissues, but so much energy is concentrated in them that their target instantly disintegrates into microparticles, forming vacuoles. This principle of exposure is called photomechanical exposure. In response to the formation of vacuoles in the dermal layer, a reaction begins that triggers the synthesis of new collagen.
The world's leading experts in the field of laser medicine, providing independent reports on fractional picosecond technologies, argue that these lasers provide an effect comparable to traditional ablative fractional lasers, absolutely painless for the patient. But the most important argument in favor of this technology for a modern metropolitan resident is ultra-short rehabilitation, which takes from three to twenty-four hours. It should also be noted that there is no need to spend time on anesthesia before the procedure, and the process itself, due to the very high pulse repetition rate, takes no more than thirty minutes. "
Lasers for skin rejuvenation can be divided into profile lasers and complex multifunctional laser systems ("combines").Each type of equipment has its pros and cons, its fans and opponents. Many cosmetologists see more benefits in the so-called laser harvester.
“The modular platform makes it possible to gradually expand the capabilities of the beautician by purchasing other attachments. Each nozzle has its own type of emitter, and buying a nozzle is always cheaper than buying a separate device. It should be remembered that such modular systems allow the doctor to have all types of lasers for solving specific problems, and not use one laser for both hair removal and rejuvenation, because the selective principle implies that each wavelength will do one thinggood, and all other indications are secondary. Therefore, modular devices with attachments were made so that the clinic did not buy 5-6 separate devices, but had one modular platform with different laser attachments, and this is always cheaper in terms of money and more rational in terms of patient loading than six separate lasers, each of whichtakes up space and is loaded with patients at best two or three days a week. "
Some people think that the multifunctional device is not suitable for large clinics where doctors work “on the fly”.
"Multifunctional machines have one important drawback: a breakdown of such a combine will mean breakdown of all functions at once, and a combine is not always a good choice for a situation when there are several specialists in the cabin" on stream "in different offices. "
In any case, the choice is up to the buyer and depends on many factors: the size of the company, the profile, the number and specialization of doctors, funding, in the end.
“The debate about the advantages and disadvantages of both versions is like arguing about the advantages of a smartphone with a camera over a DSLR. If you want to take photos, call and surf the Internet at the same time, the choice is obvious. But if you are a professional photographer, then the possibilities of the phone camera will hardly be enough for you. "
To make the right choice of laser rejuvenation machine, experts recommend focusing on the following very important aspects:
- It is necessary to request the results of clinical trials of this model from distributors.
- You should talk to specialists from different salons and clinics working on the equipment of interest, find out their feedback.
- As a rule, serious companies provide customers with the opportunity to test the device by salon specialists, so that employees and administration will be able to assess the effectiveness and advantages of the equipment offered.
- All laser devices must have a registration certificate from the Ministry of Health and a Gosstandart declaration of conformity.
- You should pay attention to the fact that the term of use of maniples in some models is limited, this implies additional costs. Therefore, you should ask the supplier to provide a document confirming the guaranteed number of impulses, and not be guided by the words of the manager selling the device.
- Be sure to check with the distributor what consumables the device has (in addition to maniples), how often they will have to be bought, how much they cost and whether they are always in stock.
- Find out how the post-warranty maintenance of the device will take place, on what conditions and in what time frame.
- Find out who and how is training specialists to work on this device, how many specialists can be trained upon purchase, under what conditions, whether the training will be repeated, if the staff of specialists in your salon changes, and on what conditions.
In conclusion, we would like to remind you that the use of laser techniques for rejuvenation requires beauty salons and clinics to have a medical license and specialists who have the right to provide services using equipment of this class - doctors who have undergone special training under the "Standard program of additional professional education of doctors inlaser medicine ".