2. • The word laser is an acronym for light
amplification by the stimulated emission
of radiation. It refers to the production of a
beam of radiation which differs from ordinary
light in the following ways:
a) Monochromaticity : lasers are of single specific
wavelength and hence of a defined frequency.
This means that laser light has a single colour.
3. b) Coherence : laser radiation is not only of same
wavelength but also in same phase . Coherence
means similar or synchronous behavior. This
means –
i. Temporal coherence – crests and troughs of
the electric and magnetic fields all occur at the
same time.
ii. Spatial coherence – photons are
unidirectional.
4.
5. c) Collimation : lasers remain in a parallel beam.
Because the radiations do not diverge the energy
is propagated over long distances.
6.
7. Production of lasers
The electrons of an individual atom remain as a
‘cloud’ of negative charge around the positive
nucleus. According to the quantum theory the
electrons can only occupy certain energy levels
or shells around the nucleus. The electrons in
the outermost orbit or shell are most affected by
outside forces. If the atom is given additional
energy , say by heating, these outer electrons
can be made to occupy higher energy levels
8. and if enough energy is added to the atom, an
outer electron may gain sufficient energy to free
itself from the pull of the nucleus. The atom
becomes +vely charged ion and electron a free –
ve charge. When the outer electrons are in one of
the higher energy states, they will tend to return
to the lower energy states, sometimes to the
most stable or ground state. An electron may do
this either by cascading down from one energy
level to the next or it may jump directly to the
ground state.
9. • In both the cases, additional energy must be
given up and this is done by giving off a photon (
quatum ) of radiation. Each step from one
energy level to the next is known as a transition
and the wavelength of the emitted photon
depends on the energy difference between the 2
energy levels, the more the energy difference ,
the shorter the wavelength and higher the
frequency.
10.
11. Components for laser production
1. Lasing medium – material which is capable of
producing laser is known as lasing medium. It
absorbs energy from the external source and
gives off its excess energy as photons of light.
2. Resonating chamber – it contains the lasing
medium which is surrounded by 2 parallel
mirrors at either ends.
3. Energy source – a flashgun is used to excite the
electrons of lasing medium. Usually current
electricity is used.
12. TYPES OF LASERS
• Various types of lases are used these days. The
commonly used lasers are:
1. Ruby lasers ( or crystal laser )
2. Helium – neon laser ( gas laser )
3. Diode laser ( semi conductor laser)
13. Measurement of laser energy
• The rate at which energy is produced or
absorbed is measured in joules per second, i. e
watts. ( 1 W = 1J/s)
• Most lasers used in physiotherapy have output
powers of milliwatts
14. Dosage
• Wavelength – visible red laser is recommended
for superficial conditions, such as wounds ,
ulcers and skin conditions and infrared for
deeper musculoskeletal structures.
• Area of treatment – discrete lesions should be
treated directly over the affected part. For
wounds and large areas , part is divided into cm
squares (GRID) and each area treated separately
or scanning method can be used.
15. • Progression – if no response , dose should be
increased. 5 or 6 treatments are said to be
sufficient to establish response to treatment.
16.
17. PRINCIPLES OF APPLICATION
Preparation of the patient-the nature of the t/t
and the need to wear goggles or spectacles is
explained to the patient.
Preparation of the apparatus- the laser
apparatus is conveniently positioned.
Preparation of the part- the surface of the skin
to be treated is cleaned with an alcohol wipe in
order to remove any material on the surface that
might absorb or scatter the radiation.
18. The part is supported in such a way that
any pressure of the laser applicator does
not cause movement or discomfort.
Application- key activates the machine
and ensures that unauthorised people
don’t switch it on . Laser applicator
applied to skin surface before switching
on. Maintain applicator in contact with
tissues so that beam is applied at right
angles in order to achieve maximal
penetration.
19. If contact not desired due to infected wound
, applicator may be held just off the
surface or covered with transparent non-
reflective film.
Treatment should not provoke pain where
tenderness is present. Position is kept
maintained. If larger area is to be treated
applicator is removed and repositioned on
a new site , turning off the output while
transfer.
20. Termination- device is switched off
before removing the applicator from the
skin contact. The details of dosage and any
patient response , such as immediate
increase or decrease of pain are noted and
recorded , plus the parameters of dosage.
21. PHYSIOLOGICAL THERAPEUTIC
USES OF LASERS
1) Wound Healing – healing of wound is thought
to be accelerated by application of laser. It is a
complex physiological process which involves
chemotactic activity , vascular changes and the
release of chemical mediators. Radiations
particularly from the red spectrum of light are
found effective in the treatment of chronic
ulcers. Laser therapy enhances wound healing
by increasing tissue proliferation.
22. 2) Tensile strength and scar tissue: the tensile
strength of the tissues treated with laser therapy
is more than the normally healed ones. This
tensile strength is directly related to the increase
in levels of collagen.
Also, wounds exposed to laser therapy have
more epithelialisation and less exudate
formation. Hence they have less scar tissue
formation with better cosmetic appearance.
23. 3) Musculoskeletal conditions :
- it if found to be effective in various overuse
tendinitis or bursitis like tennis elbow ,
golfers elbow , etc.
- also effective in some acute conditions like
ankle sprain as it enhances the healing
process and relieves pain.
- various arthritic conditions like RA , OA are
also benefited . Laser has its effect on
prostaglandin synthesis and thus relieves
inflammation.
24. • Laser therapy has bactericidal effects
because of increased phagocytosis by
leucocytes. Can be used in conjuction with
antibiotics in inflammatory conditions.
4) Pain relief : laser is found to be effective
in relieving acute as well as chronic pain. -
-Acute pain as in ankle sprain is relieved
by reducing swelling and enhancing the
healing process.
-Postoperative pain is also found to be
reduced by laser.
25. - Pain due to trigeminal neuralgia is found to be
relieved by laser therapy.
- Studies on superficial median or radial nerve
conduction velocity have shown a decrease in
sensory nerve conduction velocity by a low
intensity laser.
5) Bone and articular cartilage: longer duration of
low power laser helps in fracture healing and
bone remodulation.
- It helps in chondral proliferation and
remodelling of the articular line .
- Also useful in non- union of fractures.
26. DANGERS AND CONTRAINDICATIONS
1.Effects on eyes : main danger of low power laser
therapy is a risk of eye damage . If the beam is
applied directly into the eye lens , beam can be
focused on a very small area and cause intense
heating.
2. Effects on cancerous growth : it should not be
applied over cancerous growth as it acts as a
photo – biostimulatory agent and can accelerate
its growth .
27. 3. Effects on pregnant uterus : it should not be
applied over pregnant uterus as it can cause
abnormal growth.
4. Haemorrhagic areas areas and cardiac
conditions: it can cause vasodilatation and hence
care should be taken while exposing such area.
In cardiac patients avoid exposure around cardiac
region.
28. 5.Tattoos and Other Pigmented Tissues -Dark
pigments, such as tattoos and melanin, may
absorb light at the wavelengths used in laser
therapy. Where probes with high power
densities are in use, the absorption of laser
energy by these pigments may cause localised
heating, and subsequent discomfort or injury, of
the irradiated tissue. We recommend conducting
patch-tests on darker-pigmented tissues
29. 6.Anti-Inflammatories -Patients taking anti-
inflammatories for acute soft tissue injuries may
not respond as quickly to laser therapy as those
who are not. Ideally, we would suggest a
combination of ice and laser therapy without the
use of an anti-inflammatory.
30. Effects of 904-nm Low-Level Laser Therapy in the
Management of Lateral Epicondylitis: A Randomized
Controlled Trial
Liz Kit Yin Lam et al
Published in Volume: 25 Issue 2: May 17, 2007
• Objective: The aim of this study was to evaluate the
effectiveness of 904-nm low-level laser therapy
(LLLT) in the management of lateral epicondylitis.
• Background Data: Lateral epicondylitis is
characterized by pain and tenderness over the
lateral elbow, which may also result in reduction in
grip strength and impairment in physical function.
LLLT has been shown effective in its therapeutic
effects in tissue healing and pain control.
31. • Methods: Thirty-nine patients with lateral
epicondylitis were randomly assigned to receive
either active laser with an energy dose of 0.275 J
per tender point (laser group) or sham
irradiation (placebo group) for a total of nine
sessions. The outcome measures were
mechanical pain threshold, maximum grip
strength, level of pain at maximum grip strength
as measured by the Visual Analogue Scale (VAS)
and the subjective rating of physical function
with DASH questionnaire.
32. • Results: Significantly greater improvements
were shown in all outcome measures with the
laser group than with the placebo group (p <
0.0125), except in the two subsections of DASH.
• Conclusion: This study revealed that LLLT in
addition to exercise is effective in relieving pain,
and in improving the grip strength and
subjective rating of physical function of patients
with lateral epicondylitis.
33. Laser therapy of rheumatoid arthritis
John A. Goldman MD1,*,Joseph Chiapella MD1,Noah Bass
MD1,12 dec, 2005.
• Thirty people with classical or definite rheumatoid
arthritis received laser exposure to a Q-switch
neodymium laser that operated at 1.06 μm with an
output of 1 5 joules/cm2 for 30 nsec. One hand was lased
at the proximal interphalangeal (PIP) and metacarpal
phalangeal (MCP) joints, whereas the other hand was
sham lased. The patient, physician, and occupational
therapy evaluators did not know which hand was being
lased. Twenty-one patients noted improvement of both
their MCP and PIP joints of both hands during laser
therapy. Twenty-seven noted improvement of their PIP
joints and 26 noted improvement of the MCP joints
during therapy.
34. • Heat, erythema, pain, swelling, and tenderness
all improved with time in both hands, but the
lased hand had more significant improvement in
erythema and pain. There was also significant
improvement in grasp and tip pressure on the
lased side. The level of circulating immune
complexes as measured by platelet aggregation
decreased during lasing. The improvement may
be related to laser exposure. The exact role that
laser radiation has upon rheumatoid arthritis
and its mechanism of action remain to be
elucidated.
