What Is Ultraviolet Light Therapy?

Ultraviolet radiation therapy is a physical therapy technique that uses ultraviolet rays to irradiate the human body to prevent and treat diseases.

UV therapy

Ultraviolet radiation therapy uses

Traditional UV therapy in dermatology generally refers to the use of artificial light sources

The biological effect of ultraviolet light is the basis of its clinical therapeutic effect. The biological effect of ultraviolet has been described in detail in related chapters, and its action spectrum curve is shown in Figure 4-1. This section only briefly describes the mechanism of clinical application of UV to treat skin diseases.

Figure 4-1 Spectrum of UV effect

I: bactericidal action curve; II: vitamin D formation action curve; III: skin erythema formation action curve; IV: pigmentation action curve

(A) bactericidal effect

Ultraviolet radiation can infect wounds, which can directly kill pathogens or change the living environment of microorganisms and inhibit their growth and reproduction. The germicidal effect of ultraviolet light is related to its wavelength, and the germicidal ability of ultraviolet rays of different wavelengths varies. Those above 300nm have almost no bactericidal ability. Those below 300nm increase their sterilizing power with the shortening of the wavelength. 250 ~ 260nm is the strongest and then decreases. This is called the ultraviolet sterilization curve (Figure 4-1). And the sensitivity of various bacteria to different wavelengths of ultraviolet rays is different. Staphylococcus aureus is the most sensitive to 253.7nm ultraviolet rays. In addition, ultraviolet radiation must reach a certain irradiation intensity to have an effective bactericidal effect. Studies have shown that the intensity of the negative square of 3 × 10 cubic erg · cm can inhibit the growth of bacteria, and each bacteria is exposed to 7.6 × 10 With the effect of the sixth power photon, growth is significantly inhibited. Danish physician Niels Finsen used artificial ultraviolet rays to cure lupus vulgaris and skin tuberculosis, and was awarded the Nobel Prize in Medicine in 1903.

(B) promote the synthesis of vitamin D

It is an important physiological effect of ultraviolet radiation on the skin, with a peak wavelength at 280nm (Figure 4-1). This not only has a preventive and therapeutic effect on rickets and chondrosis, but also has a positive significance for the prevention of osteoporosis in the elderly.

(Three) promote local blood circulation

Vasodilation in the ultraviolet irradiation area improves the local nutritional status, which can speed up the elimination of inflammatory mediators and alleviate hypoxia and acidosis. The factors that cause the erythema reaction caused by ultraviolet rays can improve local blood circulation. The erythema formation curve has two peak wavelengths (Figure 4-1), which are located at 297nm and 250 ~ 260nm, respectively. In addition, blue-violet light can increase skin circulation by 100%, and most of the ultraviolet light sources are accompanied by a certain amount of blue-violet light. The improvement of blood circulation caused by ultraviolet erythema response is usually delayed, while blue-violet light has an immediate effect.

(4) Analgesic effect

Erythema UV treatment has obvious analgesic effect. The pain threshold in the irradiation area is increased, and the sensory time is prolonged, which has a good relief effect on inflammatory and non-inflammatory pain. 50% of 350nm UV can penetrate deep into free nerve endings, making these sensory nerve endings enter the intertemporal ecology (pause of conduction) and weaken pain.

(5) Anti-inflammatory effect

The bactericidal effect, the promotion of local blood circulation and the analgesic effect are all beneficial to the anti-inflammatory effect. In addition, ultraviolet light can mobilize and strengthen the body's immune function, such as UVB and UVA can stimulate the reticuloendothelial system and other functions; skin protein degeneration (additional antigen) after ultraviolet radiation causes the body to increase complement and lectin; Under the action of ultraviolet rays, the body's opsonin increases, which can promote phagocytosis. Therefore, the anti-inflammatory effect of ultraviolet light is the combined effect of the above factors.

(6) Promote wound healing

Ultraviolet rays have the effect of promoting cell growth, division and proliferation, as well as improving blood circulation, improving tissue cell nutrition and regeneration conditions, etc., all are beneficial to wound healing. It can be used clinically to treat various infection wounds, prolonged wounds and skin ulcers.

(VII) Pigmentation

It is not only conducive to enhancing the skin's ability to withstand sunlight, improve resistance to ultraviolet rays, but also a mechanism of action for treating vitiligo. There are two types: immediate hairstyle and delayed type. The former occurs immediately after irradiation. Both 300 ~ 700nm light can cause it. It is the result of melanin oxidation and melanin distribution in keratinocytes. The most effective cause of delayed pigmentation is 254 nm UVC or 340 nm UVA.

(Eight) skin keratin thickening

Ultraviolet radiation can promote skin keratin thickening, up to 2 to 3 times thicker, thereby enhancing the skin's barrier effect and reducing the penetration of harmful chemicals and allergens into the skin. In addition, a certain intensity of ultraviolet radiation on the body surface can make skin pigmentation, keratin thickening, and skin barrier defense ability; it can also enhance physical fitness, improve adaptability to environmental changes and resistance to certain diseases, such as can be used for prevention and treatment Pressure ulcers, folliculitis, rickets.

(9) Desensitization

Under multiple ultraviolet irradiation, the body produces a small amount of histamine, which continuously enters the blood from the skin, stimulating the production of histamine. When the latter has a sufficient amount, it can break down the excessive histamine in the blood during the allergic reaction, and To desensitization. Therefore, it can be used clinically to prevent and treat diseases whose main pathogenesis is type I allergy. This year's research proves that ultraviolet radiation can prevent and treat type IV allergies, such as contact dermatitis. The most effective wavelength is 297nm UVB, but the effect of UVA is not obvious.

(10) Immune regulation

When human skin is exposed to ultraviolet radiation, even if the radiation dose is relatively low, it will change the morphology and function of epidermal Langerhans cells, induce specific suppressor T lymphocytes, or induce immune suppression in the body, affecting keratinocytes. Immune activity. DNA and uric acid are the main color bases of immunological changes induced by ultraviolet radiation.

2 (12) Other people who are exposed to ultraviolet rays, such as miners and athletes, can increase their physical strength, reduce fatigue, and increase endurance. Ultraviolet light also has a significant effect on promoting the absorption of subcutaneous ecchymosis and promoting thrombolysis. It can be used to prevent and treat bedsores, frostbite, malnutrition ulcers, and early thrombotic occlusive vasculitis. In addition, it has been reported that UVB irradiation can significantly alleviate skin pruritus symptoms in AIDS patients, which is conducive to improving the quality of life of patients. Ultraviolet rays can also cure tumor cell apoptosis.