Talking about the Application of LED in Dermatology

The use of light to treat human diseases is a very old method. Sunlight has been used to treat diseases as early as thousands of years ago in countries such as China. As a new type of light source, LED has gradually been recognized by people as its biological effect, and is now being gradually applied in medicine and playing an active role. This article will explain and describe in detail the application of LED in dermatology.

First, the optical parameters that affect the biological effects of LEDs

The biological effects of LEDs depend on different optical parameters, including different wavelengths, fluence, power density, irradiation time, continuous wave or pulse wave, and the number of clinical treatments, treatment intervals, and the like. Different wavelengths can reach different parts of the skin tissue (Figure 1). In general, the longer the wavelength is, the stronger the penetrating power is. The distance of skin tissue penetrating at 400 nm does not exceed 1 mm, the distance of 514 nm penetrating is about 0.5 mm to 2 mm, and the penetrating distance of 630 nm is about 1 mm to 6 mm. At the same time, light of different wavelengths can be absorbed by different chromophores in the tissue. In the clinic, red light (630 nm to 700 nm) is often used to treat deep skin tissue structures such as sebaceous glands; blue light (400 nm to 470 nm) is used in photodynamic therapy (PDT) to treat lesions located on the epidermis If you want to reach the dermis of the skin you need a longer wavelength, such as the 660nm wavelength can reach the reticular layer of the dermis to play a role in skin fibroblasts in the dermis, and this is the principle of LED light source for photorejuvenation one. Table 1 lists commonly used LED optical parameters.

Second, LED application in dermatology medicine

1. Photorejuvenation

Photorejuvenation technology is defined as skin rejuvenation treatment using continuous strong pulsed light at low energy density without peeling. In the short years since its inception in 2000, photorejuvenation technology has rapidly spread throughout the country and has been widely used in major and medium-sized cities. It has now become one of the main means for improving skin photoaging, which can significantly improve skin wrinkles and texture. Rough, irregular pigmentation and large pores have been recognized by many technical professionals and beauty appealers. The characteristic histological changes in photoaging of the skin are elastic fibrosis in the dermal matrix and impaired maturation of collagen fibrils, resulting in loose skin and wrinkles.

Studies have found that visible to near-infrared LED light penetrates the epidermis of the skin and reaches the dermal layer of the skin. Through photothermal and photochemical effects, it promotes the regeneration and rearrangement of elastic fibers and collagen fibers, thereby reducing skin wrinkles and increasing elasticity. Table 2 lists some of the LED light source devices used for photorejuvenation.

2. Prevention or treatment of post-inflammatory hyperpigmentation Pigmentation on the skin appears to be common and difficult to avoid in skin physical and chemical cosmetology and is particularly prone to appear in Asian populations. For example, in order to reduce the degree of skin pigmentation after laser treatment in clinical practice, it is generally to avoid the season when the ultraviolet rays are too strong, to urge the patient to avoid the sun, and to apply sunscreen, but it is difficult to completely avoid pigmentation after inflammation. In recent years, studies have found that 660nm LED light can prevent or even treat the skin pigmentation that occurs after this inflammation, which will be a new research hotspot in the skin beauty industry.

3. Promote healing of wounds The various wavelengths of LED light in the near infrared can be seen to promote the growth of epithelial cells after trauma and promote wound healing. At the same time, it also has a good therapeutic effect on the healing of chronic ulcers of the lower extremities of diabetic patients.

4. Reducing inflammation A series of studies have shown that LEDs have anti-inflammatory effects. The study found that 635nm LED light can inhibit the release of inflammatory mediator prostacyclin E2 (PGE2) from gingival fibroblasts, thereby reducing the inflammatory response of the gums. In the case of pulsed dye laser treatment before the photoaging of the skin, if the LED light source is used in advance, the discomfort caused by the dye laser such as erythema, swelling and pain can be reduced. Early irradiation with LED light before radiation therapy for breast cancer patients can reduce the side effects of radiotherapy.

5. Prevention of scars Keloids are skin disorders that affect beauty and are difficult to treat clinically. They are caused by excessive proliferation of connective tissue after skin injury. Patients often have scars. The clinically started small, hard red papules grow slowly, producing round, oval, or irregular scars that rise above the surface of the skin and extend outwards like crab feet. The skin is smooth and shiny, and can be accompanied by Pain, itching and other discomfort. Clinical treatment is difficult and the effect is not ideal. Studies have found that LED can significantly improve the patient's pain, itching and other discomfort, make the scar flattened, and at the same time have the advantages of non-invasive.

6. Other effects In addition, LED can also be used as a UV-free phototherapy apparatus for photodynamic therapy, treatment of hair loss, reduce skin damage after UV irradiation, and so on.

In short, as a new type of light source, LED has been gradually applied to dermatology. With the continuous innovation of LED lamps and medical research on the mechanism of LED biological effects, the application of LED in dermatology will be extremely limited. prospect. At the same time, LED has high security and can be used as home medical equipment.