What Is Light Therapy?

Phototherapy is a physical therapy that uses the radiation of light to treat diseases. Light therapy mainly includes ultraviolet therapy, visible light therapy, infrared therapy and laser therapy.

Phototherapy

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Phototherapy is a physical therapy that uses the radiation of light to treat diseases. Light therapy mainly has

Phototherapy is a method of preventing and treating diseases by using visible light and invisible light from artificial light sources. Light therapy begins

Light therapy mainly has

The wavelength of infrared is 760 nm 50µm, which belongs to

That is, the combination of long-wave ultraviolet rays and certain photosensitive drugs to treat skin diseases, or black light therapy or photochemotherapy. Photosensitive drugs such as 8-methoxy psoralen and trimethyl psoralen (TMP) can be taken orally. Drug molecules are activated by absorbing their energy under long-wave ultraviolet radiation, and are activated by two molecules on the DNA strand in the cell. Each thymine covalently binds to form a thymine dimer. Through the light addition effect, the photosensitizer and thymine base form a C4-cyclobutadiene photoadduct, causing cell damage, inhibition or death.

Visible light can cause the light perception of the retina, its wavelength is 760 ~ 400nm, and it is composed of red, orange, yellow, green, cyan, blue, purple and other seven colors of light. Visible light therapy includes red, blue, blue-violet, and multispectral therapy. The therapeutic effects of visible light are mainly thermal and photochemical thermal effects. Visible light can cause vision. The circadian rhythm of humans and animals and a series of physiological rhythms are closely related to the lighting rhythm (alternate day and night) in nature. Red, orange, and yellow light can accelerate breathing and deepen, increasing pulse rate; green, blue, and purple light can cause breathing to slow down, lighten and slow pulse rate; blue and purple light can reduce nerve excitability and have a sedative effect Red light improves the excitability of nerves and has a stimulating effect. At the same time, visible light can also enhance glucose metabolism, promote the oxidation process, strengthen pituitary function, improve cerebral cortex function, strengthen the excitability of the sympathetic nervous system, and enhance the body's immunity. Since the 1970s, visible light has been used to treat neonatal jaundice. Bilirubin has the strongest absorption of light with a wavelength of about 400 to 500 nm, and the maximum absorption band is 420 to 460 nm, which belongs to the blue-violet light segment. After bilirubin absorbs blue-violet light, it decomposes into a series of transformants, gradually turns into a light yellow low-molecular-weight water-soluble compound, and is quickly excreted from the urine. Skin light flow can be increased by 224% under light, which is beneficial for bringing bilirubin from the deep part of the body to the skin's superficial tissues for irradiation. Jaundice subsided after exposure to blue light, serum bilirubin decreased, and green and dark brown thin stools were excreted.
The indications and contraindications of visible light therapy are basically the same as infrared therapy. The thermal effect that requires a deeper effect, a larger range and a more uniform cut is the main choice of visible light.
The visible light source for clinical applications is mainly tungsten filament incandescent lamps, with a spectrum of about 4.8% for visible light and 95% for infrared. For monochromatic light irradiation, a filter plate can be added under the lamp head ^[3]

Ultraviolet light is invisible light that is outside the violet light and has a wavelength smaller than that of the violet light, and has a wavelength of 400 to 180 nm. Light quantum energy is high, and it has obvious photochemical effects.
Medical ultraviolet is divided into three segments: long-wave ultraviolet (400-320nm); medium-wave ultraviolet (320-250nm); short-wave ultraviolet (250-180nm). Sunlight contains a large amount of ultraviolet rays, but the short-wave ultraviolet rays are almost completely absorbed by the atmosphere, so only long- and medium-wave ultraviolet rays are radiated to the ground. Short-wave UV is obtained from a reliable artificial light source.

Biological effects of UV

Erythema reaction: after a certain period of time after the skin is irradiated with a certain amount of ultraviolet rays, the boundary presented on the skin is clear and uniform, and the reaction is congestive. The skin's absorption of ultraviolet light is related to its wavelength. The shorter the UV wavelength, the shallower the depth of penetration into the skin. Therefore, most of the short-wave and medium-long-wave UV are absorbed by the skin's stratum corneum and spiny cell layer. After UV irradiation, a certain period of time must elapse before the erythema reaction occurs. This period is the incubation period. The length of the incubation period is related to the wavelength of ultraviolet light. The incubation period of long-wave ultraviolet erythema is long, generally 4-6 hours, and the incubation period of short-wave ultraviolet erythema is short, generally 1, 5-2 hours. The erythema response peaks in 12-24 hours, and then gradually decreases. The nature of ultraviolet erythema is a type of actinic dermatitis, which belongs to non-specific inflammation. There are four kinds of theories about the mechanism of ultraviolet rays to produce erythema: one is the histamine theory. Ultraviolet light degrades and decomposes tissue proteins, decomposes histidine in the tissue, forms histamine, and releases histamine, which causes the capillaries of the dermal papilla to expand and increase permeability, manifested as skin hyperemia and erythema. However, the formation of erythema is not a simple histamine effect; ultraviolet rays act on the lysosomal membrane of spinal cells, releasing a variety of enzymes such as hydrolase, decomposing proteins, and expanding blood vessels to form erythema; prostaglandins are important active substances that cause ultraviolet erythema. Kallikrein and histamine are co-factors; ultraviolet light degrades vascular endothelial cells, leading to the production of kinin and erythema.
The blood vessels in the erythema are dilated, blood pressure is reduced, white blood cells are increased, phagocytosis is enhanced, and immune capacity is significantly improved. Therefore, ultraviolet radiation has anti-inflammatory, analgesic, analgesic, and anti-infective effects; it can also accelerate tissue regeneration and can be used for chronic ulcers that do not heal wounds. It has a good effect on rheumatic inflammation of the muscles and nerves or superficial acute and chronic suppurative inflammation, but it can not aggravate the spread of lesions due to tuberculous inflammation, so it should not be used.
After a certain dose of ultraviolet radiation, skin pigmentation can occur to varying degrees after a certain period of time. Melanin deposition is strong after long-wave UV irradiation, and pigmentation is weak after short-wave UV irradiation. Melanin can be combined with free electrons and other chemical free radicals generated by the skin's photochemical process under ultraviolet radiation to prevent their damage to the body. The mechanism of skin pigmentation is that ultraviolet rays can act on the pituitary-adrenal cortex system to enhance the secretion of melanocyte stimulating hormone, thereby promoting the melanin particles in melanocytes (secreting cells between epidermis and dermis) to change from a reduced state to an oxidized state. Enhance the phagocytosis of melanin particles by epidermal cells and strengthen skin pigmentation. Utilizing the pigmentation of ultraviolet rays can treat vitiligo, especially the combination of long-wave ultraviolet rays and photosensitizers.
Effect on calcium and phosphorus metabolism. Ultraviolet light can transform 7-dehydrocholesterol in human skin into vitamin D3. Vitamin D3 can promote the absorption of calcium and phosphorus in the intestine and the calcification of bone tissue. Can treat pediatric rickets and adult osteochondrosis. In addition, calcium ions can reduce the permeability of blood vessels and nerve excitability, can reduce allergic reactions, and is one of the mechanisms of UV desensitization.
Adjust and improve the functions of the nervous, endocrine, digestive, circulatory, respiratory, blood, and immune systems.
Ultraviolet bactericidal effect: DNA mainly exists in the chromosomes of the nucleus, and is the core of cell reproduction, development, and growth. DNA has a strong absorption of medium and short-wave ultraviolet rays. Therefore, ultraviolet rays with a wavelength of 220 to 300 nm have a bactericidal effect. Utilizing the bactericidal effect of ultraviolet rays, it can disinfect and clean wounds, and treat various infections such as skin, mucous membranes, wounds, sinus tracts, and fistulas.
Large doses of ultraviolet light can cause RNA destruction, protein breakdown and protein denaturation, which is consistent with the damage to DNA. It is one of the mechanisms of ultraviolet disinfection and cleaning wounds. The use of photosensitizers to strengthen the inhibitory effect of UV on DNA and RNA can treat proliferative skin diseases such as psoriasis.
In addition, when the ultraviolet light reaches a certain intensity, it can be destroyed

Laser is stimulated radiation, which has the characteristics of small divergence angle, good directivity, pure spectrum, good monochromaticity, high energy density, large brightness, good coherence, etc., and has thermal effects, mechanical effects, and electromagnetic effects. Can be used for the diagnosis and treatment of many diseases.

Biological effects of laser

Thermal effects: mainly caused by lasers in the visible and infrared regions. The thermal effect causes the tissue temperature to rise with the increase of laser energy. When using the laser thermal effect in clinical treatment, the appropriate laser energy needs to be selected according to the specific situation.
Pressure effect: The laser has a very high energy density and generates a lot of pressure. The use of laser pressure to treat diseases such as tattoo removal and urinary system stones can also be crushed and excreted by laser pressure.
Photochemical action: Biological macromolecules are activated by absorbing the energy of laser photons, generating excited atoms, molecules and free radicals, causing a series of chemical changes in the body, called photochemical reactions. Photochemical reactions can lead to reduced or inactivated enzymes, amino acids, proteins, nucleic acids, and so on.
Electromagnetic effect: Laser is an electromagnetic wave, and its electric field intensity is very high, which can be used to treat tumors.
Biological stimulation: Low-intensity laser irradiation can affect the body's immune function, play a two-way regulation role, and can enhance the phagocytosis of white blood cells. Appropriate dosage can inhibit bacterial growth, promote red blood cell synthesis, strengthen intestinal villus movement, promote hair growth, accelerate wound and ulcer healing, promote fractured epiphysis growth, accelerate healing, accelerate repair of nerve tissue damage, and enhance adrenal function, Enhance protein activity and more.

The role of laser in clinical treatment

High-intensity laser <br /> High- intensity laser refers to the irreversible damage caused by laser light on biological tissues, and its output power is above the watt pole. In clinical practice, the laser is used to coagulate, stop bleeding, fuse and vaporize the exposed tissue, or to remove the diseased tissue.
Widely used in surgical operations, such as esophageal disorders, gastrointestinal anastomosis, hepatobiliary disorders requiring surgery, incision treatment of burns, urethral stricture, prostate cancer, thyroid surgery, breast surgery, intracranial tumor surgery, various anal surgery, etc. And a variety of dermatological disorders such as warts and verrucous condyles, vascular lesions, skin malignancies and so on.
Low-intensity laser < br Low-intensity laser can regulate the body's immune function, accelerate ulcer and wound healing, accelerate fracture healing, have obvious anti-inflammatory and analgesic effects, and promote bile secretion, spleen's hematopoietic function and regulate the endocrine system .
Used for skin diseases such as shingles, rosacea, erythema polymorpha, urticaria, cervical spondylosis, lumbar disc herniation, periarthritis, myofiberitis, acute and chronic injuries, acute mastitis, cystic hyperplasia of the breast, Bronchial asthma, arthritis, cervical erosion, chronic pelvic inflammatory disease, facial nerve paralysis, vascular headache, neuralgia, eczema of the external ear canal, allergic rhinitis, pharyngitis, etc.

High-power lasers with an output power above 500mV are more damaging to the human body, and their visible light and diffuse reflection light in the near-infrared region are also dangerous.
Eye protection < br The protection of squinting eyes mainly uses protective glasses (reflection, absorption, discoloration, warning)
Skin protection < br For lasers that exceed the threshold, wear white work clothes and gloves. Do not let the laser light directly to the skin. Prevent reflected and scattered light from irradiating the skin. Laser workers must perform regular health checks.

After a small dose of ultraviolet radiation, the synthesis of DNA and RNA is inhibited and then accelerated, which can promote the growth of granulation and epithelial tissue and wound healing. It has good curative effect for the treatment of pressure ulcers in various stages. In addition, ultraviolet radiation can also expand blood vessels, accelerate blood flow, improve local blood circulation, strengthen local nutrition, and improve the body's immune function. A large number of animal experiments and clinical practices have shown that low-energy laser irradiation has good anti-inflammatory and tissue repair functions, can expand blood vessels, improve microcirculation, increase red blood cell oxygen carrying capacity, enhance the body's immune capacity, and stimulate macrophage phagocytosis The ability and regeneration of granulation tissue, thereby promoting wound healing. In recent years, foreign scholars have found that semiconductor lasers have better anti-inflammatory and anti-infective effects than other low-energy lasers. The mechanism of action is mainly to reduce the permeability of blood vessel walls, reduce inflammation exudation, congestion and edema, and activate macrophages. The function of the system improves the body's overall and local immunity, and plays an anti-inflammatory and anti-infective role. Laser irradiation promotes the formation and growth of new blood vessels, increases the content of nuclear nucleic acid and glycogen in the cell, and proliferates fibroblasts. The growth of granulation tissue leads to the regeneration of new epithelial tissue. Semiconductor laser can also increase the balance of RNA content in the cytoplasm and DNA content in the nucleus, promote protein synthesis, and stimulate wound healing. Ultraviolet combined with semiconductor laser for bed sores has good antibacterial and anti-inflammatory effects, can accelerate wound healing, and is not easy to repeat. It is effective for bed sores, and is simple and safe to operate. It is worthy of clinical promotion and combined application. However, for mild to moderate bedsores, the cure rate is higher and the cure time is faster, suggesting that clinical care should be found in time and treated as soon as possible.