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Light therapy (phototherapy)
Last reviewed: 03.07.2025
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Light therapy (phototherapy) is a method of local or general exposure to non-coherent non-polarized electromagnetic radiation of the optical spectrum of the corresponding parameters, including the infrared, visible and ultraviolet parts of this spectrum, which is carried out using an emitter located above a certain exposed area of the patient's body at a distance of 10-100 cm.
The advantages of phototherapy are the practical absence of contraindications and side effects, methodological simplicity, and the possibility of combining with pharmacological drugs.
Phototherapy is used to treat patients with various neurological and mental illnesses (depression, seasonal affective disorders, insomnia, premenstrual syndrome, parkinsonism, focal dystonic hyperkinesis, psychovegetative syndrome, tension headaches) and to improve the adaptation of healthy people to night work and to flights across several time zones. In some cases, phototherapy is more effective than medications and other treatment methods.
The peculiarities of the action of incoherent unpolarized EMI of the optical spectrum are related to:
- with resonance phenomena of various biological structures and radiation of a certain wavelength,
- with the energy power of photons of the corresponding parts of this spectrum,
- with the PPM of radiation of a particular wavelength.
Light therapy (phototherapy) with the optical spectrum of EMI used in physiotherapy is represented by the ultraviolet part with a wavelength from 180 to 400 nm, the visible part with a wavelength from 400 to 760 nm and the infrared part with a wavelength from 760 nm to 10 μm.
The interaction of EMR of the optical spectrum of different wavelengths by the resonance mechanism is associated with the absorption of this radiation by the corresponding biosubstrates. The pattern is determined by the size and complexity of the structure of the biosubstrate. Thus, the spectrum of EMR absorption by amino acids is in the ultraviolet part, larger molecules absorb EMR of the visible part, and the maximum absorption of DNA is in the red and near infrared part of the optical spectrum of EMR.
The energy of an EMI photon in the ultraviolet part of the spectrum is 300 kJ/mol or more, in the visible part - from 120 to 300 kJ/mol, in the infrared part - 120 kJ/mol or less. Due to the high energy of photons in the ultraviolet and closely located visible part of the optical spectrum, chemical bonds are broken (strong interactions that determine the chain structure of biopolymers), and macromolecules, primarily proteins, are destroyed. Photons with lower energy power initiate various electrodynamic changes with subsequent conformational rearrangements of biological substrates.
The PPM of the EMI optical spectrum is usually not indicated in light therapy, since the PPM is associated with a specific wavelength (spectral density of radiation). However, the total PPM of the ultraviolet part of the optical spectrum is within 0.1-10 mW/cm2. In the visible and infrared parts, the total PPM reaches several W/cm2 with a clear predominance even in the visible part (70-80%) of the spectral density of infrared radiation, and this explains the predominance of the thermal effect and the increase in the temperature of the irradiated skin. The main clinical effects:
- under ultraviolet irradiation - pigment-forming, immunostimulating, photosensitizing! Bactericidal and bacteriostatic;
- when exposed to visible light - vasoactive local anesthetic, metabolic, anti-inflammatory;
- with infrared irradiation - anti-inflammatory (anti-edematous), regenerative-proliferative, local anesthetic, vasoactive, metabolic.
[ Equipment used for light therapy (phototherapy)
- ultraviolet radiation generators: "ORK-21M" (mercury-quartz irradiator on a tripod), "OKN-11M1 (tabletop ultraviolet irradiator), "BOD-91 (bactericidal irradiator on a tripod), "EOD-101 (erythema irradiator on a tripod), "ON-7" and "ON-82ya (irradiators for the nasopharynx), "BOP-4" (portable bactericidal irradiator), etc.;
- visible radiation generators: household incandescent lamps, “VOD-11” (stationary irradiator on a tripod), etc.;
- Infrared radiation generators: "LSS-6M" (stationary "Sollux" lamp), "LIK-5M" (tabletop reflector with infrared emitter), "LSN-1M (tabletop "Sollux" lamp), Minin lamp (electric medical household reflector), etc.
Phototherapy is carried out with biolamps of a certain power. Daily exposure is 30-60 minutes. It is carried out in the morning hours for at least 10 days. The minimum illumination that gives a therapeutic effect is 2500 Lx. A biolamp of a special design recreates the solar spectrum without ultraviolet rays. The biolamp allows for treatment both in hospital and outpatient settings (including at home), it can be used in any room.