The principle of modern laser hair removal machines is based on the principle of "selective photothermolysis" proposed by American doctors Aderson and Parrish in 1983: a certain wavelength of laser light passes through the epidermis, enters the dermis, and is selectively absorbed by the hair and hair follicles. The melanin granules of the hair are absorbed, resulting in a photothermal effect, and the heat energy in the hair is conducted to the surrounding, completely destroying the "hair roots" such as hair follicles and stem cells, resulting in permanent hair removal. The normal tissue around the hair follicle does not absorb the laser because it does not contain melanin particles, so the effect is very small and generally does not cause paralysis.
Indications, contraindications, complications
1. Indications: Suitable for dark and light-colored hair in all parts, but invalid for white hair.
2. Contraindications: patients with scar constitution, infected lesions in the treatment area or a history of herpes simplex, those who have used other methods (wax removal, electrolytes, etc.) for hair removal within 6 weeks, allergic to hydroquinone or other bleaching agents or within 6 months Those with a history of using 13-cis retinoic acid.
3. Complications: The common complications are postoperative local erythema and follicular edema, which can subside spontaneously after a few hours. Less common complications are local crusting, purpura, blisters, hyperpigmentation or hypopigmentation, and increased sebum production.
Steps
The technical operation of laser hair removal seems to be very simple, but the experience of the operator affects the treatment effect. Although the operation of each machine will vary, generally the following steps should be included:
1. Investigate the medical history, examine the recipient, analyze the skin type, and check the hair condition.
2. Turn on the power and preheat the machine.
3. Preparation of the treatment area: The hair should be shaved before treatment, because the visible hair will damage the epidermis due to the high heat caused by the laser burning, and it can also cause irreversible damage to the laser guide head and cause unpleasant odor, but mechanical equipment cannot be used. Plucking or waxing for hair removal. In addition, the area should be cleaned to remove grease and dirt.
4. Set the treatment parameters and perform the trial treatment.
5. Get the best parameters and complete the whole treatment.
6. Check the reaction after treatment and explain relevant precautions.
Precautions for use
1. During the treatment, both the doctor and the patient should wear laser protective glasses to prevent the eyes from being damaged by the laser.
2. The overlapping of the spots should not be too much. Repeated irradiation will aggravate skin damage. If the spacing is too wide, the treatment effect will be affected.
3. When using semiconductor laser hair removal, such as using cooling hand tools or hair removal under intense pulsed light, a certain pressure should be applied to the hand tool during the treatment, so that the hand tool can maintain good contact with the skin, and it can also drive away local blood and reduce hair loss. Oxyhemoglobin absorbs laser energy.
