The progress of science and technology has led to the emergence of various new medical instruments, such as laser, computed tomography, nuclear magnetic resonance and so on. Among them, the invention of laser has the greatest influence on dermatology, and laser has gradually changed the face of dermatology: with the help of laser, dermatology has changed from a simple treatment to a specialist medicine that pays equal attention to both treatment and beauty.
What is a laser?
Simply put, it is the amplification of light by stimulated radiation, which has the characteristics of high energy, single wavelength, single phase potential and low scattering angle, so it can destroy specific substances with high selectivity without harming other substances. For skin, a highly complex organ, laser is a sharp weapon for treatment. It can remove abnormal tissues or lesions and keep normal tissues. In other words, compared with traditional treatment tools, laser can improve the treatment effect and reduce the side effects of treatment. It must be emphasized that laser is just a tool, not a panacea. There are many diseases that cannot be treated by laser. On the contrary, there are many diseases that can be treated by laser and traditional methods. The effect is not inferior to laser treatment, but the cost is much less.
Traditionally, lasers used in dermatology can be roughly divided into three categories:
The first type is laser with water as absorption medium, such as CO2laser and Erbuim-YAG laser, which can carbonize water-containing tissues, so they can be used for cutting, removing senile plaques and warts, or removing wrinkles and grinding skin. Because the pulse width of traditional carbon dioxide laser is too long, it will cause thermal damage to the nearby skin, form eschar, prolong the time required for wound healing and erythema after operation, and easily form scars, which is more likely to cause long-term pigmentation of yellow people after operation. So it is not a good choice to use the traditional carbon dioxide laser to grind the skin. Fortunately, many new types of carbon dioxide lasers have appeared in recent years, such as ultrashort pulse, trupulse, nova-Pulse and so on. Or CPG silk touch, feather touch and other models, which can effectively avoid the above side effects. More importantly, the appearance of the Kerr-Jacob laser. The wavelength of Er-Jakob laser is 2940nm, and its water absorption capacity is ten times higher than that of CO2 laser with 10600nm. Therefore, it can accurately remove the target substance, without causing thermal damage to the nearby skin, forming eschar, shortening the time required for wound healing, shortening the time for erythema after operation, and not easily forming scars.
The second kind of laser mainly uses black substance as absorption medium:
For example, Q-switched ruby laser, Q-switched rubidium-Jacob laser, Q-switched alexandrite laser, etc. Because the pulse width of these lasers is very short, for example, the pulse width of Q-switched ruby laser is only 25-40 nanoseconds (ns). Therefore, it can effectively destroy melanin or black tattoo substances on epidermis or dermis, and has a very good therapeutic effect on various mother spots with blue-black appearance, such as Ota mother spot, cheekbone mother spot, freckle, solar nevus, leaky keratosis, tattoo, eyebrow tattoo, eyeliner tattoo, etc. There are others, such as coffee milk spot and baker's mother spot. , can also be improved.
The third laser with heme as therapeutic target;
For example, long pulse dye laser and long wavelength dye laser pumped by flash lamp have curative effects on all kinds of red vascular mother spots, microvascular dilatation, rosacea, even tinea corporis and viral warts. The original dye laser excited by flash lamp has a wavelength of 585nm and a pulse width of 450μs, so the depth of vascular lesions that can be treated and the size of blood vessels are limited. Fortunately, with the appearance of dye laser with adjustable long wavelength, the wavelength can be adjusted to 585, 590, 595 and 600nm, and the pulse width is 450μs or 1ms, which greatly increases the therapeutic effect, especially in conjunction with the use of epidermal cooling system.
In recent two years, two kinds of lasers appeared, which expanded the service scope of dermatology.
The first is the invention of hair removal laser. Based on the principle that the thermal relaxation time of hair follicle is much longer than that of melanin particles, the pulse width of the second-class laser such as Q-switched ruby laser and Q-switched emerald laser is extended from 25 nanoseconds (ns) to the order of 1- 10 microsecond (ms), so it can be selective. It must be emphasized that because hair has its growth cycle, the hair follicles that can be removed by hair removal laser are currently growing hair follicles, not resting hair follicles. Therefore, laser hair removal is not effective at one time, but because the hair growth cycle of different parts is different, there must be different treatment cycles and times. Generally speaking, it takes at least three treatments to have a satisfactory effect.