Mode of Action of Laser In Tissues

1. Action of laser on tissues
“Laser in Orthopedic
Surgery”
(Part-2)

2. Laser
“Red light aids in the production of ATP in cells, which increases
cellular health and energy. The radiation (energy) in normal cells
stimulates adjacent cells to divide in the normal process of
regeneration and healing. Laser light stimulates abnormal tissue to
activate normal inter-cellular radiation, thus stimulating the
normal healing process to start again. The photons produced by
laser light normalize tissue by activating enzymes within cells.
Once activated, enzymes within a cell trigger a chemical reaction
in which more enzymes are activated in a domino-type effect. Low
Level Laser Therapy has no effect on normal tissue. Photons will
only be absorbed by cells that need them.”
Holistic Bird Newsletter,
www.holisticbird.com/hbn01/decjan/pages/laser.htm

3. Absorption of laser in
Tissue:
•The IR( Infra red) region of the
spectra, water molecules are
dominant absorbers.
••In the UV (Ultraviolet) and visible
spectra, absorption by
macromolecules like melanin and
hemoglobin is more pronounced.

4. Electromagnetic Spectrum:
Wavelength: It is the distance between repeating units of a propagating wave
of a given frequency.
Frequency: It is the number of occurrences of a repeating event per unit time.

5. Basic steps of laser action on biologic
tissues:

6. Laser-tissue
interactions

7. Basic effects of laser on tissues

8. Laser-tissue interactions

9. Mechanism of action of laser:

10. Basic effects of laser
on tissues:•.
1. Thermal effects .
2. Mechanical effects.
3. The photoablative effect.
4. The photodynamic effect.
5. Photochemical and
Photobiological effects.

11. Thermal action of a laser beam can
be described as one of three types,
depending on the degree and the
duration of tissue heating:
A. Hyperthermia:
B. Coagulation:  
C. Volatilisation:

1 . Thermal effects of lasers:

12. Phenomena of thermal effects
of laser :

13. 1. Coagulation/ cauterizing of tissues,
2. Tissue vaporization for incising or excising.

Recently, thermal power of laser have been widely
used by surgeons to
a. Cut into tissues ( carbon dioxide laser scalpel),
b. Stop internal hemorrhage (Neodymium: YAG and
argon laser photocoagulation) and-
c. Treat tumors.
Application of Thermal effects of
lasers:

14. Video clip on cutting (Thermal) effect
of laser:
HOYAG~20.WMV

15. Thermal effects of a laser
beam.
Laser osteotomy with the CO2-laser

16. Thermal effects of a
laser beam.

17. 2. Mechanical effects
•Nd:YAG lasers, a very high intensity of luminous flux
over a small area (between 1010 and 1012 W/cm2)
ionizes atoms and creates a plasma.
•At the boundary of the ionized region, there is a very
high pressure gradient which causes the
propagation of a shock wave. It is the expansion of
this shock wave which causes the destructive effect.
Application of mechanical effects:
a. General Surgery : coetaneous angiomas.
b. Eye: principally in ophthalmology
c. Urology: Endoscopic removal of kidney
stone.

18. Mechanical effectsof laser :

19. 3. The photoablative effect
of laser:
•This effect is defined by as a pure ablation of
material without thermal lesions at the
margins, such as one would get with a
scalpel. It occurs because of the principle of
dissociation.
• The molecular bonds are broken and the
tissue component are vaporized, without
generation of any heat at the edges.

20. Uses of
Photoablative effects
of laser:
•1. Orthopedic Surgery:
•2. This procedure is for patients presenting
with refraction problems.
a. Myopia b. Hypermetropia, c. keratitis
d. keratinisation, e. keratoplasty .
The photoablative effect offers no practical advantage
for making incisions or for ablating vascular tissues
because they will bleed in the same way as with a
scalpel. It can only be used on tissues which will not
bleed.

21. Video clip on photoablative
effect of laser:
PLLD.WMV

22. The photoablative effect of laser:

23. Photoablative effect of Laser:

24. Application of photoablative
effects

25. Application of
photoablative effects

26. 4. The photodynamic effect
•


Photodynamic therapy (PDT) is based on photoactive
drugs that produce excited singlet-state oxygen molecules
from local (ground-state) oxygen molecules under
illumination with visible light.1 The singlet oxygen
produces reactive oxygen species, primarily free radicals
such as ·OH. These free radicals attack DNA and other
vital biomolecules in the cell, leading to cell death..
Due to the limited tissue penetration of visible light, PDT
has mostly been utilized for skin cancers.
Applications:
Cancer
Psoriasis
Macular degeneration

27. The photodynamic effect of
laser:

Photodynamic therapy works by the patient receiving a
photosensitizing agent or photosensitizer which is a drug
that exposes cancerous cells to the laser light which kills
these cells. The photosensitizer has the ability to
differentiate between good body cells & cancerous cells,
and will not diffuse in the good cells, leaving to expose only
cancerous cells.

28. The photodynamic effect of
laser:

29. 5. Photochemical
and
Photobiological
effects of Laser:

30. Photochemical and
Photobiological effects of Laser:
•Photobiology is the scientific study of the
interactions of light (technically, non-ionizing
radiation) and living organisms.

•This field includes the study of photosynthesis,
photomorphogenesis, visual processing,
circadian rhythms, bioluminescence, and
ultraviolet radiation effects

31. Application of Photochemical and
Photobiological effects of Laser:
•To subside inflammation and Pain.
•To enhance wound, ulcer/ Bedsore
healing.
•Bone tissue/ nerve regeneration /
growth.
•Laser photosynthesis of previtamin D3.
•Laser Hair Removal/ Growth .
•Cosmetic/ LIPO-LASER Fat Dissolving
Laser .
•Treatment of impotance.
•Cessation of smoking.

32. To subside
inflammation and Pain.

33. To subside
inflammation and Pain.

34. To subside inflammation and
Pain.

35. To subside inflammation
and Pain.

36. Healing skin ulcer, wound
Bedsore.

37. Hard and soft tissues (Bone/ Muscular /
nerve tissue) regeneration / growth.

38. Laser photosynthesis of
vitamin D.

39. Hard and soft tissues (Bone/ Muscular /
nerve tissue) regeneration / growth.

40. Hard and soft tissues (Bone/
Muscular /nerve tissue)
regeneration / growth.

41. Bye.
•See you next day
with
•“Laser in Orthopedic
Surgery”
(Part-3)
Laser on Soft
Tissue