Low-Level Laser Therapy

Question 1

What is the term used to describe giving up energy?

Answer 1

Spontaneous emission

Question 2

What are the visible light wavelengths?

Answer 2

400-700nm

Question 3

What are the principles of Laser generation?

Answer 3

• Adding energy to electrons causes them to
move to higher orbit
– the atom is in an “excited state”
• If the electron gives up energy it moves to
a lower orbit
– the atom goes back to “ground state”
• Giving up energy is called spontaneous
emission.

Question 4

What are the 5 steps in the production of laser?

Answer 4

1. Pumping of Active Medium
2. Population Inversion
3. Spontaneous Emission
4. Stimulated Emission
5. Amplifiction

Question 5

The longer the wavelength (lower frequency) the ______ penetration

Answer 5

deeper

Question 6

What are the therapeutic wavelengths?

Answer 6

632.8 to 905 nm

Question 7

T/F: As the concentration of melanin or hemoglobin increase, the
depth of penetration of the light decreases

Answer 7

True

Question 8

Describe the application of LLLT?

Answer 8

Laser should be in light contact with the patient
– Beam does diverge slightly, keep it close
• 90o angle to the treatment area
• Cover each square centimeter of the treatment
area
– Called gridding technique (as if a grid is drawn on pt)
• Alternate method = scanning technique.
– Hold the laser 5 - 10mm from skin.
– Energy level decreases with distance
– Alter intensity to take that into account

Question 9

What are the 4 laws again?

Answer 9

1. Arndt-Schultz Law
2. Grotthuss-Draper Law
3. Inverse Square Law
4. Lambert’s Cosine law

Question 10

What are the biological effects of LLLT?

Answer 10

• Photobiomodulation – photochemical
effects
– Effect is not from heating tissues but from the
absorption of photons of light by cells
• Photobiostimulation
– Lower doses of laser
• Photobioinhibition
– Higher doses of laser

Question 11

What are chromophores?

Answer 11

Molecules which accept energy from photons

Question 12

What are cytochromes?

Answer 12

In mitochondria
– Sensitive to light photons (600 – 904 nm)
– Absorption of photons triggers biochemical
reactions

Question 13

What are the indication for LLLT?

Answer 13

• Wound healing
• TMD
• Myofascial pain
• Osteoarthritis
• Rheumatoid arthritis
• Tendinopathy
• Trigger Points
• Epicondylitis
• Neck and low back pain

Question 14

FDA classifications

Answer 14

• Class I – (“exempt” lasers) invisible lasers.
– Laser printers and CD players “safe under reasonably foreseeable
use”
• Class 1M - wavelengths between 302.5 nm and 4000 nm,
– safe except when used with optical aids (e.g. binoculars).
• Class II – (“low-power”) visible lasers
– Hazardous if directed continually into the eye. (laser pointers)
• Class III – moderate risk to the retina but not to the skin or
tissues. Operator and patient must wear protective eye wear
– IIIa – 1mW -

Question 15

What safety precautions need to be taken when using LLLT?

Answer 15

• Protective eyewear is recommended when
using all lasers.
• Light reflex response is absent with
wavelengths over 700nm
• Protective eyewear is required with Class
IIIb and Class IV laser devices.
• Glasses should block specific wavelength

Question 16

What are the contraindication for LLLT?

Answer 16

• Cancer
• Pregnancy – over the abdomen and pelvic
area
• Avoid direct exposure to eyes
• Over areas of active hemorrhage
• Over the thyroid gland
• Directly over open wounds, unless
covered with a clear protective barrier
• Epileptic patients

Question 17

What are some precautions to using LLLT?

Answer 17

• Infection
• Testicles
• Sympathetic ganglia, vagus nerve, cardiac
region in those with heart disease
• Open growth plates
• Bruises
• Photosensitive skin

Question 18

LLLT for Acute injuries:

Answer 18

• First 48 hours  [5-1000 Hz]
• To stimulate (heal) or inhibit (pain relief)
• Smaller, more frequent, and localized
doses are generally more advantageous
than larger, systemic dose
• Treatment times around 3 min

Question 19

LLLT for Chronic injuries:

Answer 19

Temporary increase in pain may be noted
– Less than 24 hours
– Move from “chronic” to “acute” phase
– Larger doses may be necessary to achieve
treatment responses
• Stimulate ONLY (