2. What is Laser Therapy?
Light Amplification by the Stimulated Emission of Radiation
Compressed light of a wavelength from the cold, red part of the spectrum
of electromagnetic radiation
Monochromatic - single wavelength, single color
Coherent - travels in straight line
Polarized - concentrates its beam in a defined location/spot
Albert Einstein – 1st described this theory that was transformed in to laser
By the end of the 60’s, Endre Mester (Hungary) -
was reporting on wound healing through laser therapy
In early 1960’s, the 1st low level laser was developed.
In Feb. 2002, the MicroLight 830 (ML830) received FDA approval for Carpal
Tunnel Syndrome Treatment (research treatment)
Laser therapy – has been studied in Europe for past 25-30 years; US 15-20
5. LASER Regulation
LASERs - classified by the FDA’s Center for Devices & Radiological Health
based on the Accessible Emission Limit (AEL).
Class Levels 1-4
1 = incapable of producing damaging radiation levels (laser printers & CD players)
2 = low-power visible lasers (400-700 nm wavelength, 1 mW)
3 = medium-power lasers - needs eye protection
3a – up to 5 mW
3b** – 5 mw-500 mW
4 = high-power lasers– presents fire hazard (exceeds 500 mW)
6. Types of Lasers
Energy – 1-500 mW
Therapeutic (Cold) lasers produce maximum
output of 90 mW or less
600-1000 nm light
Energy – 3000-10000 mW
7. Types of Lasers
Four categories of lasers
Crystal & Glass (solid - rod)
Synthetic ruby & others (synthetic ensures purity)
Gas (chamber) – 1961
HeNe, argon, CO2, & others (HeNe under investigation)
Semiconductor (diode - channel) - 1962
Gallium Arsenide (GaAs under investigation)
Liquid (Dye) - Organic dyes as lasing medium
Chemical – extremely high powered, frequently used for military purposes
8. Laser Generators
Components of a generator:
Power supply – electrical power supply that can deliver up to 10,000 volts & 100’s amps
Lasing medium – gas, solid, liquid
Pumping device –
high voltage, photoflash lamps, radio-frequency oscillators or other lasers (pumping is used to describe the process
of elevating an orbiting electron to a higher, excited energy level)
Optical resonant cavity – contains lasing medium
9. Low level laser therapy
Laser Therapy Acronym is Light Amplification by Stimulated Emission of Radiation
Low-level laser therapy (LLLT) is a pain-free, non-invasive, affordable tool used by
physical therapists throughout the healing process that is becoming more prevalent in PT
practices nationwide .
Laser Therapy works on the principle of inducing a biological response through energy
transfer, in that the photonic energy delivered in to the tissue by the laser modulate the
biological processes within the tissue. So it is called PHOTOBIOMODULATION.
10. Low level laser therapy continue……
The photobiomodulation can have both:
a) Photobiostimulative effect
b) Photobioinhibitive effect
The Laser Therapy effectiveness based on the principle of ‖
Schultz law‖of biomodulation.
The Arndt-Schultz law of Biomodulation infers that low dosage of photonic energy
will stimulate the biological process in the tissue the higher dosage of photonic energy
will inhibit the biological process in the tissue.
11. Low level laser therapy continue……
Lasers require the following components to be operational.
• 1- Power supply: Lasers use an electrical power supply that can potentially deliver up to
10,000 V and hundreds of amperes.
• 2- Lasing medium (material): This is the material that generates the laser light. It can
include any type of matter: gas, solid, or liquid
• 3- Pumping device (excitation mechanism or energy source): "Pumping" is the term
used to describe the process of elevating an orbiting electron to a higher, "excited" energy
level Fig. (68). This creates the population inversion that is essential for laser operation.
The pumping device may be high voltage, photoflash lamps, radio-frequency
oscillators, or other lasers.
• 4- Optical resonant cavity: This contains the reflecting mirrors (full or partial reflecting
13. Low level laser therapy continue……
• Properties of laser
Monochromaticity: Laser light is concentrated in a narrow range of wavelength (same
wavelength and same color).
Coherence: All photons emitted in one phase (same time and distance).
Collimation ( directionality): In one direction and non-spread (Focusing the beam of
light on certain point).
14. Lamb light Vs Laser light
1 Many wavelengths
16. Classification of laser
1. According to nature of the material placed between two reflecting
2. According to intensity.
3. According to hazards.
17. Classification of laser continue…
1. According to nature of the material placed between two reflecting surfaces.
a) Crystal lasers (solid state lasers) include
- Ruby crystal (aluminum oxide and chromium)
- Neodymium crystal is embedded in yttrium-aluminium garnet (Nd:YAG) lasers.
b) Gas lasers include
- Helium neon (HeNe)
- Carbon dioxide (CO2)
c) Semiconductor or diode laser
- Gallium arsenide (GaAs)
d) Liquid laser
- Polyphenyle - Oxazine
e) Chemical laser
- Laser with high intensity not used therapeutically but used in industrial production
18. Classification of laser continue…
2. According to intensity.
a) High power: known as "hot" lasers because of the thermal responses they generate. These
are used in the medical realms in numerous areas, including surgical cutting and
coagulation, ophthalmologic, dermatologic, oncologic, and vascular specialties.
b) Low power: known as "low power laser therapy" or "low level laser therapy". It used for
wound healing and pain management. These lasers produce a maximal output of less than
1 milliwatt (1 mW = 1/1000 W) causing photochemical, rather than thermal effects. No
tissue warming occurs.
19. Classification of laser continue…
3. According to hazards.
a) Class 1 (less than 0.5 mW)
Visible and non-visible
No eye or skin danger
Laser printers, car entry, CD players
No heating/no healing
Safe in all uses unless focused through magnifier
a) Class 2 (less than 1 mW)
Safe for short periods on eyes and extended on skin
Safe because blink reflex limits retina exposure
No healing/no heating.
20. Classification of laser continue…
a) Class 3 (1mW to 500 mW)
Visible and invisible.
Helium neon (HeNe).
Galium Arsenide (GaAs)—infrared.
MPE can be exceeded with limited effects (skin).
Protective eye ware if direct viewing of beam.
a)Class 4 (more than 500 mW)
Increases tissue temperature--can burn
CO2, Argon, YAGlaser
Eye danger can result from indirect or reflected beam
21. Classification of laser continue…
• Most Commonly Used Lasers
Helium neon (HeNe)
Gallium arsenide (GaAs).
22. Classification of laser continue…
1- Helium neon (HeNe)
The HeNe gas laser uses a gas mixture of primarily helium with neon in a pressurized tube.
This creates a laser in the red portion of the electromagnetic spectrum with a wavelength of
632.8 nm. The power output of the HeNe can vary, but typically runs from 1.0 to 10.0 mW,
depending on the gas density used.
24. Classification of laser continue…
2- Gallium arsenide (GaAs)
• The GaAs lasers utilize a diode to produce an infrared (invisible) laser at a wavelength of
904 nm. Diode lasers are composed of semiconductor silicone materials that are precisely cut
and layered. An electrical source is applied to each side, and lasing action is produced at the
junction of the two materials. The cleaved surfaces function as partially reflecting surfaces
that will ultimately produce coherent light.
• The 904-nm laser is delivered in a pulsed mode because of the heat produced at the junction
of the diode chips.
• N.B: Diode laser can single beam or multisource cluster beam
27. Physiological effects
1- Reducing Pain
a) There is an increase in serotonin (5-HT) levels (inhibit pain transmission to brain
and from nociceptors).
b) There are also increases in Beta Endorphins, which decrease pain sensation.
c) Decrease bradykinins (is an inflammatory mediator. It is a peptide that causes blood
vessels to dilate (enlarge)) which can be prevalent in injured tissue, induce pain
sensation by stimulating nociceptive afferents.
d) Increase release of Acetylcholine: Acetylcholine helps normalize nerve signal
transmission in the autonomic and somatic pathways.
29. Physiological effects continue…
2- Reducing Inflammation
a) Enhancement of ATPby stimulation of mitochondria.
b) Stabilization of the Cellular Membrane.
c) Acceleration of LeukocyticActivity
d) Increased Angiogenesis (is the physiological process through which new blood vessels
form by vascular endothelial cells in proliferation (growth of new tissue)).
30. Physiological effects continue…
3- Promoting Tissue Healing
a) Increased macrophage activity.
b) Increased fibroblast proliferation.
c) Keratinocyte proliferation. (Keratinocyte: the outermost layer of the skin
The primary function of keratinocytes is the formation of a barrier against environmental
damage by pathogenic bacteria, fungi, parasites, and viruses, heat, UV radiation)
a) Early epithelialization.
b) Growth factors increase (Growth factors: act on stimulating cellular growth, proliferation and
healing. Examples are fibroblast growth factors and vascular endothelial growth factors
stimulate blood vessel differentiation (angiogenesis).
31. Physiological effects continue…
4- Recovery from nerve injury
a) Accelerate nerve regeneration ( by stimulation of Nerve growth
b)Increase frequency of action potential.
c) Increase rate of nerve conduction.
5- Increase bone and cartilage formation
( by stimulation of bone morphogenetic proteins that stimulate
bone cell differentiation)
32. Indications of laser therapy
1. Dermatological disorders
2. Pain and inflammation in orthopedic and sport cases.
a) Ankle sprain
b) Chronic Low back pain
c) Tennis Elbow
d) Plantar fasciitis
e) Frozen shoulder
3. Neurogenic pain
a) Trigeminal neuralgia
33. Treatment procedures
1) Preparation of the patient:
• a) The skin in the area of electrode placement should be cleaned by saline
water, soap or Vaseline to lower skin resistance.
• b) Special gels, sprays or water is applied to the skin as a condition medium
for better stimulation.
• c) Electrodes should be fixed in position, using mending tapes to maintain
good contact throughout the treatment period
35. Clinical application of laser
1. Calculation of laser dose dependent on:
(1) The output power of the laser in mw.
(2) The time of exposure in seconds.
(3) The beam surface area of the laser in cm2 (area of irradiation).
Energy or total energy (Joule) = Watts X Seconds
Time of exposure (seconds) = Joules/Watts.
37. Clinical application of laser
2. Depth of Penetration
a)HeNe laser energy Absorbed rapidly in the superficial structures,
especially within the first 2-5 mm of soft tissue. The response that occurs
from absorption is termed the "direct effect." HeNe laser has an indirect
effect on tissues up to 8-10 mm.
a)The GaAs, which has a longer
wavelength, is directly absorbed in
tissues at depths
of 1-2 cm and has an indirect effect up to 5 cm.
39. 3) Laser treatment techniques
There are two main techniques
1. Contact technique: GaAs only for trigger points
or around wound.
2. Non-contact technique: for HeNe and GaAs
for superficial wounds or stimulation of
Clinical application of laser
40. 1. Basford, J. Low intensity laser therapy: Still not an established tool. Lasers in Surgery and
2. Basford, JR, Sheffield, CG, Harmsen, WS. Laser therapy: A randomized, controlled trial of the effects of low-
intensity Nd:YAG laser irradiation on musculoskeletal back pain. Archives of Physical Medicine and
3. Basford, JR, Sheffield, CG, Mair, SD, Ilstrup, DM. Low-energy helium neon laser treatment of thumb
osteoarthritis. Archives of Physical Medicine and Rehabilitation. 1987;68:794–797.
4. Bertolucci, LE, Grey, T. Clinical analysis of midlaser versus placebo treatment of arthralgic TMJ degenerative
joints. Journal of Craniomandibular Practice. 1995;13:26–29.
5. Bradley P
, Groth E and Rajab A (1998): Low intensity laser therapy for hard tissue problems of the oro-facial
region. Proceedings of the 6th International Congress on Lasers in Dentistry. London, pp. 103–105..
6. Brosseau, L, Welch, V, Wells, G, deBie, R, Gam, A, Harman, K, Morin, M, Shea, B, Tugwell, P
. Low level laser
therapy (classes I, II and III) for the treatment of osteoarthritis. The Cochrane Library, Issue 2. Update
Software, Oxford; 2000.