laser hair removal is hair removal by destroying hair follicles play a role in melanin within the hair follicle growth phase in most of the laser emitted the strongest absorption, laser hair removal to determine the best role of target. The more melanin, the more clear, the higher the hit rate, the greater the destruction of hair follicles.
everyone is obsessed with a smooth skin, so many kinds of cosmetic products such as river carp, dizzying, but trapped in the lip hair, hand hair, leg hair long There is much to people who are the other plus armpit hair, pubic hair, etc., in order to fast, quick removal of these small plush, traditional hair removal Act removed the clip from the simplest to the shaving method, patch, wax hair removal, chemical reagents hair removal , EA hair removal, etc., there are people willing to try. Their role is only temporary, common drawback is that regeneration of hair quickly.
electrolysis (electriolysis) and thermal dissolution method (thermolysis) although the effective destruction of hair follicles, but the operation is cumbersome, time-consuming, low efficiency, low efficacy, significant pain and possible shortcomings left scars. To be effective, convenient and safe removal of unwanted hair surface, based on principles of selective photothermolysis, a variety of laser systems have been designed and intense pulsed light source system that allows people to accept a large area hair removal treatment significantly reduced discomfort, and to scar formation and other complications to a minimum. The use of modern optical technology has been able to achieve permanent hair removal reduction purposes.
early as 60 years, Goldman first described ruby ??laser damaging effects of melanin on the hair follicles, but not for clinical, 80 Ohshiro described ruby ??laser treatment nevi after the hair loss, but skin and causing serious injury. In 1993, Harvard University Medical Optics Laboratory Wellman started using ruby ??laser hair removal research, followed by ruby ??laser, Nd: YAG laser hair removal treatment for clinical succession, but their design is also less than ideal parameters. Wellman Laboratories of Medical Optics in 1997 started a new generation of laser hair removal machine-LightSheer semiconductor laser hair removal device for clinical treatment, and achieved remarkable results. , The new intense pulsed light hair removal treatment systems began to be used, since the optical hair removal technology has been basically mature.
1 Principle of laser hair removal
the principle of laser hair removal is still Based on theory of selective photothermolysis. Hair follicle and hair shaft are rich in melanin, melanin distributed in the hair bulb matrix between cells, and also the structure of the hair shaft to the transfer (such as the medulla, cortex and cuticle). Melanin as a target of laser can precisely and selectively target hair removal treatment. Melanin in the absorption of laser energy, the temperature rapidly increased, resulting in tissue damage around the hair follicle, the hair removed.
under the theory of selective photothermolysis, just select the appropriate wavelength, pulse width and energy density, the laser can accurately without causing damage to the hair follicles adjacent tissue damage. To achieve the effect, it is clear above the hair bulb and the bulge (in the sebaceous hair follicle openings and setting of muscle attachment between the hair follicle outer root sheath, where is the location where the hair follicle stem cells) in melanocytes must be light therapy . ① deeper parts of the hair bulb, decided to use longer wavelength, light penetrates deeper treatment. On the other hand, if the wavelength is too short, the epidermal melanin in the hair follicle melanin will absorb more energy competition, which can lead to skin damage. Therefore, to ensure better absorption of light known as the black, while the wavelength of the laser hair removal is better to 695-1064 nm. ② To achieve high efficiency of the hair follicle damage is obviously a solution to increase the laser irradiation time. In theory, by lengthening the laser pulse width, close to the hair follicles of the thermal relaxation time can improve efficacy, the longer pulse width, the tiny structures, such as epidermal melanosome injury less likely, and relatively large any color hair follicle structure, and its more vulnerable to injury within the melanocytes. The diameter of the hair follicle is about 200-300μm, the thermal relaxation time of hair follicles 40-100ms. Therefore, the ideal laser pulse width should be in the tens of milliseconds to 100 milliseconds. A recent study found that patients with dark skin for more than 100ms pulse width laser, not only has better efficacy and fewer side effects.
hair growth cycle and the relationship between hair removal treatment: ① by laser catagen, no effect on quiescent hair, only the other of these Laser hair to work into the growth period, so the laser hair removal requires multiple treatment, the effect can be significant. ② If a part of the small proportion of hair in the growing season, the number of treatment should be increased. Conversely treatment times can be reduced. ③ Based on different parts have different hair growth cycle, there are differences between each treatment interval. Such as head hair has a relatively short period of resting, so the interval of time can be as short as l month; trunk and limbs relatively long hair resting, so treatment interval to February or so. ④ the depth of hair follicles varies by location, such as the depth of deep to be used longer wavelength laser treatment, whereas shorter wavelength can be used, such as shallow depth of the laser treatment. ⑤ If a part of the hair follicle density is too high, then the treatment should be appropriate to reduce the laser energy.
2 laser hair removal treatment
Laser Hair Removal indications and contraindications: laser hair removal for all parts of the dark and light hair, but the white hair is invalid.
the following is the relative contraindications of laser hair removal:
① has a history of keloids;
② infection in the treatment area or a history of herpes simplex infection;
③ in 6 weeks, had used other means (such as wax off) hair removal patients;
④ hydroquinone or other bleaching agent allergy;
⑤ within 6 months using Lsotretinoin (13 - cis retinoic acid) history.
preoperative preparation: For darker skin type Ⅲ - Ⅴ skin type patients before surgery to avoid sunlight as much as possible, preferably with sunscreen for 4-6 weeks, there pigmentation tendencies also can be added with hydroquinone drugs prevention. In addition, the treated area of ??skin preparation before surgery completely shave the hair, and its role are:
① treatment area can reduce the absorption of some laser hair occurs because of discomfort caused by coking
② can reduce odor emissions from burning hair.
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