PRINCIPLE MECHANISM

Principle and mechanism of photoelectric treatment of melasma

Photoelectric treatment of melasma mainly relies on the selective absorption of the energy of melanin particles in the lesion site by the laser spot, so that the melanin particles quickly expand and rupture after absorbing the energy, and then the phagocytes in the body engulf these small fragments of melanin particles and excrete them out of the body, thereby achieving the purpose of treatment. Different photoelectric technologies have different mechanisms for improving melasma. The photoelectric equipment used clinically to treat melasma includes intense pulsed light, Q-switched laser, fractional laser, picosecond laser, non-ablative fractional laser, radio frequency technology and other types.

PARAMETER SETTING

Parameter settings for different photoelectric devices to treat melasma

According to the "Expert Consensus on Photoelectric Treatment and Repair of Chloasma", taking OPT technology as an example, patients with dark skin and heavy skin lesions are suitable for 640nm/615nm filters, three pulses, pulse width 4ms, pulse delay 35-40ms, energy density 15-17J/cm²; patients with lighter skin and lighter skin lesions are recommended to use 560nm/590nm filters, triple pulses or double pulses, pulse width 3-3.5ms, pulse delay 30-35ms, and energy density 14-17J/cm². The endpoint reaction of treatment is a slight deepening of the color of the pigmented patches, or no visible color change. New and active skin lesions that are still progressing should be treated with caution.

According to the "Guidelines for the Diagnosis and Treatment of Common Diseases Related to Laser Cosmetology (2024 Edition)", the parameter setting requires mild intensity, the initial energy should not be too high, the treatment interval should not be too short, and the treatment endpoint is a mild flushing reaction. For example, the 755nm picosecond laser in fractional mode has a wavelength of 755nm, a frequency of 10Hz, a spot diameter of 6-8mm, an energy density of 0.4-0.7J/cm², a treatment interval of 1.5 months, and 4 treatments.

The 755nm picosecond laser in ZOOM mode has two parameter schemes, one is a spot diameter of 4.4-5.1nm, an energy density of 0.88-1.18J/cm², 3 scans, a total pulse number of 1000 times, 1 treatment per month, a total of 4 times, and the endpoint reaction of the treatment is slight redness of the skin; the other is a frequency of 10Hz, a spot diameter of 6-8mm, an energy density of 0.4-0.71J/cm², and the endpoint reaction of the treatment is slight redness and slight heat of the skin, with a treatment interval of 1.5 months, and 4 treatments.

Non-ablative fractional laser may be more suitable for specific situations such as mixed melasma. During treatment, attention should be paid to the individualized setting of parameters such as dose, spot coverage, number of treatments, and treatment cycle.

1565nm non-ablative fractional laser, energy density 10-15mJ/cm², 150-200 tiny beams/cm², square spot, side length 12mm, overlap rate of about 10%, set parameters according to the patient's skin color and other conditions, the treatment endpoint reaction is slightly red at the lesion.

Currently, the first choice for the treatment of melasma is low-energy large-spot Q-switched Nd:YAG laser, with conventional parameters of spot 6-8mm, energy 1.0-3.0J/cm², frequency 10Hz, treatment interval 2-4 weeks, and the clinical treatment endpoint is slight erythema of the lesion that disappears within a few hours.

It has also been reported that the recommended parameters for Q-switched 694nm ruby fractional laser are spot size 6-8mm, energy 2.5-3.5J/cm², frequency 1-1.5Hz, and treatment interval 2-4 weeks.

The parameters of different instrument manufacturers are slightly different. At the same time, the photoelectric devices for treating melasma are diverse. The parameter settings of each device need to be adjusted individually according to the specific conditions of the patient (such as skin color, skin lesion color, disease activity, etc.). At the same time, attention should be paid to observing the treatment endpoint reaction during treatment to ensure the treatment effect and reduce the risk of adverse reactions.

References:

1. Guidelines for the diagnosis and treatment of common diseases related to laser beauty (2024 edition)

2. Expert consensus on photoelectric treatment and repair of melasma

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The core founding team of Suzhou Foremed Legend Medical Technology Co., Ltd. comes from Peking University and other well-known universities at home and abroad. Foremed Legend focuses on the design, research and development and application of high-end medical beauty optoelectronic equipment based on compliance and product strength. It is committed to becoming a leading enterprise in the field of high-end medical beauty optoelectronic equipment in the world, a provider of integrated intelligent solutions for diagnosis and treatment, and a pioneer of medical beauty data integration platform.

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