Laser Depilation is based on the principle of selective photothermodynamics, by reasonably adjusting the laser wavelength, energy, and pulse width, so that the laser passes through the skin surface to reach the root hair follicle of the hair. The rich melanin in the hair follicle absorbs the light energy and converts it into heat energy , The temperature rises sharply, causing the destruction of the hair follicle tissue, making the hair lose its ability to regenerate, thus achieving the effect of hair removal. This method can not only achieve the purpose of permanent hair removal or postpone the time of hair regeneration, but also avoid and reduce the disadvantages of traditional hair removal techniques.

For people

1. Congenital or acquired thick hairs.
2. Patients with pale skin and dark hair pigment.
3. Those who wish to remove hair permanently.

Taboo crowd

1. Patients who have used wax removal, electrolysis and other hair removal within 6 weeks are not suitable for laser hair removal.
2. Some drugs may stimulate the growth of hair and affect the effect of laser hair removal. Therefore, those who have used 13-cis retinoic acid within 6 months or used photosensitizers within 3 months should suspend laser hair removal.
3. Those with infected lesions in the treatment area.
4. The treatment area has herpes simplex, tattoo, or has undergone skin transplantation.
5. A history of keloids and hypertrophic scars.
6. People with diabetes, hypertension, severe heart disease, and malignant tumors.
7. Those with blood diseases and disorders of coagulation mechanism.
8. Women during menstruation, pregnancy or lactation.
9. Psychological abnormality or mental abnormality.

Description of effect

Maintenance time: Generally speaking, laser hair removal can be maintained for a long time.

Influencing factors: laser hair removal

Factors such as personal physique, operating specifications, daily care and other factors will affect the effectiveness and duration of different patients after treatment.

Changes in time: Laser hair removal requires multiple treatments to achieve permanent hair removal. If the foot treatment is not performed, the hair will regenerate over time.

Advantages and Disadvantages

1. Advantages

Only for the hair follicle melanin, it does not harm normal skin; the treatment is fast, the pain is low, and it does not delay normal life and work; it can make the hair lose its ability to regenerate and achieve a lasting hair removal effect.

2. Disadvantages

There are limitations, suitable for people with light skin and dark hair; careful maintenance and strict sun protection after surgery; multiple treatments are required for the effect to last.

Prognostic factors

1. Wavelength

Commonly used clinical wavelengths are 694nm, 755nm, 800/810nm, 1064nm and so on. These wavelengths of laser light can be well absorbed by the melanin in the hair follicles and hair shafts, while at the same time ensuring their penetration into the hair follicles. The ruby laser wavelength is 694nm, which can be strongly absorbed by melanin, but the melanin in the epidermis can also competitively absorb more laser energy and cause postoperative pigment changes. Semiconductor laser (wavelength 800 ~ 810nm), long pulse emerald laser (wavelength 755nm) and strong pulse light are basically similar in efficacy, but under the same treatment times, long pulse Nd:YAG laser (wavelength 1064nm) may be more effective than semiconductor laser, The long pulse emerald laser is slightly worse.

2. Pulse width

The diameter of the hair follicle is 200 to 300 μm, the thermal relaxation time is 40 to 100 ms; and the thermal relaxation time of the epidermis is 3 to 10 ms. According to the theory of selective photothermal action, the pulse width of the hair removal laser should be greater than the thermal relaxation time of the epidermis and less than the thermal relaxation time of the hair follicle. Therefore, the ideal pulse width range for laser hair removal is 10-40ms. Theoretically, the longer the pulse width, the less heat is distributed in the single layer of skin, the smaller the possibility of damage to the small structures in the epidermis, such as the melanin body, and the more the larger structures, such as the melanin body in the hair follicle, It is easy to be damaged, thus avoiding the burn caused by the sudden warming of the epidermis due to the absorption of light energy. Therefore, by lengthening the laser pulse width to bring it closer to the thermal relaxation time of the hair follicle, the therapeutic effect can be improved. For patients with dark skin, it is better to use a laser with a pulse width of more than 100ms, which not only has better efficacy but also has fewer side effects。

3. Energy density

The size of the energy density determines the therapeutic effect of the same part. Enough energy can maximize the destruction of the stromal cells of the hair follicle, hinder and stop the growth of hair, thereby improving the hair removal effect; but for those with dark skin tones, choose low energy density because Such patients have more melanocytes in their epidermis, which can easily absorb energy and cause side effects such as pain, pigment changes, and blisters.

4. Number of treatments

The number of treatments in different parts is different, and the number of treatments is proportional to the effect. For example, laser hair removal can remove about 30% of the hair in one treatment, 40% to 50% of the hair can be removed in two treatments, and 60% can be removed in three treatments. ~80% of hair.

5. Treatment interval

Hair has a growth period, and the next laser hair removal should be performed when new hair grows. The laser hair removal of the arm requires multiple treatments to achieve the purpose of permanent hair removal. The general treatment cycle is 3 to 6 times a The course of treatment is 1 month apart.

6. The patient’s skin type and hair color and thickness

The laser cannot distinguish the melanin in the hair follicle and the epidermis, so the most ideal target for laser hair removal is patients with light skin and very pigmented hair. The darker the skin color of the patient, the more energy the epidermis competes to absorb, and the more complications such as pigmentation and scarring are. The hair removal effect of thicker and darker hair is good, and the hair removal effect of thinner light hair is poor.