Low-Power Laser Therapy(LPLT), Indication, Contraindication

Low-Power Laser Therapy(LPLT)
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Low-Power Laser Therapy(LPLT)/Infrared Radiation Therapy (IR) sometimes called infrared light is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye, although IR at wavelengths up to 1050 nanometers (nm)s from especially pulsed lasers can be seen by humans under certain conditions.[rx][rx] IR wavelengths extend from the nominal red edge of the visible spectrum at 700 nanometers (frequency 430 THz), to 1 millimeter (300 GHz).[rx] Most of the thermal radiation emitted by objects near room temperature is infrared. As with all EMR, IR carries radiant energy and behaves both like a wave and like its quantum particle, the photon.

Infrared (IR) radiation is electromagnetic radiation with wavelengths between 760 nm and 100,000 nm. Low-level light therapy (LLLT) or photobiomodulation (PBM) therapy generally employs light at red and near-infrared wavelengths (600–100 nm) to modulate biological activity. Many factors, conditions, and parameters influence the therapeutic effects of IR, including fluency, irradiance, treatment timing and repetition, pulsing, and wavelength. Increasing evidence suggests that IR can carry out photostimulation and photobiomodulation effects particularly benefiting neural stimulation, wound healing, and cancer treatment. Nerve cells respond particularly well to IR, which has been proposed for a range of neurostimulation and neuromodulation applications, and recent progress in neural stimulation and regeneration are discussed in this review.

Another Name

You may have heard of red light therapy (RLT) by its other names, which include:

Low-Power Laser Therapy(LPLT)

Types of Low-Power Laser Therapy(LPLT)

IR is divided into different bands: Near-Infrared (NIR, 0.78~3.0 μm), Mid-Infrared (MIR, 3.0~50.0 μm) and Far-Infrared (FIR, 50.0~1000.0 μm) as defined in standard ISO 20473:2007 Optics and photonics — Spectral bands []

Infrared light immediately follows red light on the electromagnetic spectrum.  Infrared (IR) light energy is broken down into three groups:

  • Near-Infrared – also called infrared-A (IR-A).  Near IR spans wavelengths 760 to 1,400 nm.  Most home therapy devices use these wavelengths.
  • Mid Infrared – also called infrared B (IR-B) – These wavelengths are used in many household electronic devices such as remote controls.
  • Far Infrared –  or IR-C– also known as longwave infrared, thermal infrared (thermal-IR).  This is the largest part of the IR spectrum, used in infrared saunas.

Most studies showing benefits of red/NIR light therapy used light outputs of 20-200mW/cm2. This is basically a measurement of power density – how much power the light is emitting (in watts) over how big of an area. To put that in different terms, if you shine the light on your torso (let’s say, for the sake of ease of calculation, that it’s an area of 50cm x 40cm, which equals 2,000cm2). And the light you’re using is 200 watts (which is 200,000mW), then you have 200,000mW/2,000cm2 = 100mW/cm2

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A third scheme divides up the band based on the response of various detectors:[rx]

  • Near-infrared – from 0.7 to 1.0 µm (from the approximate end of the response of the human eye to that of silicon).
  • Short-wave infrared – 1.0 to 3 µm (from the cut-off of silicon to that of the MWIR atmospheric window). InGaAs covers to about 1.8 µm; the less sensitive lead salts cover this region.
  • Mid-wave infrared – 3 to 5 µm (defined by the atmospheric window and covered by indium antimonide [InSb] and mercury cadmium telluride [HgCdTe] and partially by lead selenide [PbSe]).
  • Long-wave infrared – 8 to 12, or 7 to 14 µm (this is the atmospheric window covered by HgCdTe and microbolometers).
  • Very-long wave infrared (VLWIR) – (12 to about 30 µm, covered by doped silicon).

Indications of Low-Power Laser Therapy(LPLT)

Additional clinical research is needed to prove that RLT is effective. At the moment, however, there’s some evidence to suggest that RLT may have the following benefits:

  • Promotes wound healing and tissue repair
  • Improves hair growth in people with androgenic alopecia
  • Help for the short-term treatment of carpal tunnel syndrome
  • Stimulates healing of slow-healing wounds, like diabetic foot ulcers
  • Skin Wounds
  • Photo prevention
  • Relieve pain
  • Stiffness
  • Fatigue of rheumatoid arthritis
  • Ankylosing spondylitis
  • Potentiate photodynamic therapy
  • Treat ophthalmic, neurological, and psychiatric disorders, and
  • Stimulate the proliferation of mesenchymal and cardiac stem cells
  • Reduces psoriasis lesions
  • Aids with short-term relief of pain and morning stiffness in people with rheumatoid arthritis
  • reduces some of the side effects of cancer treatments, including oral mucositis
  • Improves skin complexion and builds collagen to diminish wrinkles
  • Helps to mend sun damage
  • Prevents recurring cold sores from herpes simplex virus infections
  • Improves the health of joints in people with degenerative osteoarthritis of the knee
  • Helps diminish scars
  • Relieves pain and inflammation in people with pain in the Achilles’ tendons
  • Reduce the signs of damage, DNA damage, [rx] and aging from UV rays[rx]
  • Reduce wrinkles[rx]
  • Reduce color patches, hyperpigmentation, and skin discoloration[rx]
  • Enhance collagen synthesis and collagen density (research has shown it can enhance the production of collagen by 31%)[rx],[rx]
  • Accelerate repair in the epithelial layer of skin
  • Combat other skin conditions like acne, keloids, vitiligo, burns, herpes virus sores, and psoriasis
  • Speed wound healing by enhancing skin tissue repair and growth of skin cells
  • Chronic neck pain[rx]
  • Knee pain[rx]
  • Fibromyalgia
  • Low back pain
  • Chronic pain in the elbow, wrist, and fingers
  • Chronic joint disorders
  • Sacroiliac joint pain
  • Chronic tooth pain
  • Osteoarthritis pain
  • Tendinitis and myofascial pain[rx]
  • Benefit cognitive performance and memory
  • The improved mitochondrial function of brain cells
  • Have a protective effect on neurons
  • Improve cellular repair of neurons
  • Increase brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)
  • Decrease brain inflammation (decreased pro-inflammatory cytokines and increased anti-inflammatory cytokines)

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Various medical applications of IR radiation for different cells and tissue tissues.

Medical ApplicationsAuthor, referenceTargetThe light source or materialWavelengthsResults
Wound HealingToyokawa et al. []Skin wound in ratCeramic-coated sheet5.6 ~ 25 μm (maximal intensity of 8 ~ 12 μm)Promoted wound healing and expression of TGF-β1
Wound HealingGupta et al. []Dermal abrasions in miceDiode laser810 nmEnhanced collagen accumulation and healing effects
Wound HealingSantana-Blank et al. [, ]Soft tissues in the ratDiode laser904nmPromotes wound healing and exclusion zone (EZ) growth (1H-NMR 1/T2)
Wound HealingSantana-Blank et al. []
Rodríguez-Santana et al.[]
Soft tissues in the ratDiode laser904nmPromotes wound healing, membrane effect measured by 1H-NMR tau(c)
Neural StimulationWells et al. []Rat sciatic nerveFree electron laser2.1, 3.0, 4.0, 4.5, 5.0, and 6.1 μmGenerated a spatially selective response in small fascicles of the sciatic nerve
Neural StimulationJenkins et al. []Adult rabbit heartDiode laser1.851μmInduced optical pacing of the adult rabbit heart
Neural StimulationIzzo et al. []Gerbils auditory nerveHolmium: YA G laser2.12 μmOptical radiation stimulated the cochlear response amplitudes
Neural StimulationDuke et al. []Rat sciatic nerveDiode laser1.875μmHybrid electro-optical stimulation generated sustained muscle contractions and reduced the laser power requirements
Neural StimulationShapiro et al. []HEK-293T cellsDiode laser1.889 μmAltered the membrane electrical capacitance during optical stimulation transiently
PhotoagingDarvin et al. []Human skinRadiator equipped with a water filter600 ~1500 nmFormed free radicals and decreased the content of β carotene antioxidants
PhotoagingSchroeder et al. []Human dermal fibroblastsWater-filtered IR-A irradiation source760~14 40 nmIncreased expression of MMP-1 in the dermis
Antitum or ActionTsai et al. []HeLa cervical cancer cellWaveguide Thermal Emitter3.6, 4.1 or 5.0 μmCaused a collapse of mitochondria l membrane potential and an increase in oxidative stress.
AAntitumorActionChang et al. []Breast cancer cells and normal breast epithelial cells.Blackbody source equipped with 3~5 μm filter3~5 μmInduced G 2 /M cancer cell cycle arrest, remodeled the microtubule network and altered the actin filament formation
Antitumor ActionTanaka et al. []A549 lung adenocarcinoma cellsNIR radiator equipped with a water filter1.1~1.8 μmActivated the DNA damage response pathway
AAntitumorActionYamashita et al. []A431 (vulva), A549 (lung), HSC3 (tongue), MCF7 (breast) and Sa3 (gingiva) cancer cellsFIR radiant-panel incubator by coating a carbon/silica/a luminum oxide/titanium oxide ceramic4~20 μm (maxim um at 7 to 12 μm)Suppressed the proliferation of cancer cells through enhancing the expression of ATF3 gene
Antitum or ActionSantana-Blank et al.[]Solid tumor Clinical trialDiode laser904nm88% anticancer effect. Ten years follow up
Antitum or ActionSantana-Blank et al.[]Solid tumor cytomorphologyDiode laser904nmSelective apoptosis, necrosis, anoikis in tumor tissues of cancer patients
Antitumor ActionSantana-Blank et al. []Solid tumor T2wMRI-MicrodensitometryDiode laser904nmEvidence of interfacial water exclusion zone (EZ) as a predictor of anti-tumor response in cancer patients
Antitumor ActionSantana-Blanket al.[]Solid tumor serum levels of cytokines of peripheral leucocyte subsetsDiode laser904nmImmuno-modulation in cancer patients of TNF-α sIL-2R and CD4+CD45 RA+ and CD25+ activated
Brain Neural RegenerationNaeser et al. []Mild traumatic brain injuryNIR diodes870 nmImproved cognitive function, sleep and post-traumati c stress disorder symptoms
Brain Neural RegenerationLapchak et al. []Strokes in embolized rabbitsLaser source808 nmIncreased cortical ATP content
Adipose RegenerationWang, Y., et al. []human adipose-derived stem cellsDiode laser810 nm
Stimulate the proliferation and differentiation
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Contraindication of Infrared Radiation Therapy

Treatment Contraindications forIRR Light Therapy

  • Open wounds
  • Metastatic Lesions
  • Areas of decreased sensation
  • parts of the body with metal implants, like in a total knee replacement of lumbar fusion
  • Near or over a pacemaker
  • the uterus during pregnancy
  • Over the gonads
  • Malignancies and precancerous lesions
  • On patients with vascular abnormalities, i.e. deep vein thrombosis, emboli, severe atherosclerosis
  • The eye directly
  • Over the stellate ganglion
  • For hemophiliacs not covered by factor replacement
  • The spinal cord after laminectomy
  • Directly over metal implants
  • Over an electronic device
  • Tissues previously treated with deep Xray or radiation
  • Tuberculosis (local)
  • Damaged or at-risk skin, i.e. skin rash, eczema
  • Anesthetic areas
  • Excitable tissue,
  • With pregnant women
  • Around the eyes, breasts, or sexual organs
  • Over fractured bones
  • Near or over an implanted electrical stimulation device
  • Women who are pregnant should consult their physician before beginning IRR light therapy treatments.
  • Clients with epilepsy should consult their physician before beginning IRR light therapy treatments.
  • You must wait five days after Botox or cosmetic fillers.
  • Some thyroid conditions.
  • People with a history of skin cancer
  • Systemic Lupus erythematosus should also avoid this kind of treatment.
  • The use of photosensitizing medications (i.e. lithium, melatonin, phenothiazine antipsychotics, and certain antibiotics). 
  • Diseases that involve the retina of the eye 


Low-Power Laser Therapy(LPLT)

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