2. • Light Amplification by Stimulated Emission of Radiation
• Laser is a device that produces and amplifies light by
stimulated emission of radiation
• It can produce light in the ultraviolet, visible, and infrared
region of the electromagnetic spectrum
• History:
– 1960: Ruby (first laser)
– 1961: Neodymium-doped (Nd): glass laser
– 1964: Nd: YAG and Argon (Ar)
– 1965: CO2 laser
3. Differences between ordinary light and LASER
Ordinary light Laser
Radiation emitted over a
wide range of wavelength
Light leaves the source
with a high degree of
collimation with very
narrow divergence
Light intensity decreases
at the distance due to
divergent beam
Directionality and high
beam intensity is
maintained in space over a
long distance
4. Components of a LASER
• LASER consists
− Lasing medium contained in an optical cavity
− Pumping system provided by external energy
• The mirrors at each end ensure that the photons bounce back
parallel to the axis, and in turn collide with excited atoms and
stimulate further production of photons
5. Mechanism of production of LASER light
• An atom consists of a dense nucleus
around which electrons move in orbit and
they are free to change their orbit to a
higher level by absorbing energy from an
external source and thus acquire an
excited unstable state
• Unstable electrons cannot stay in the
higher unstable orbit and tend to decay
to a lower more stable orbit
6. • In the process they lose extra energy
of the higher level in the form of
photons
• A photon released from an excited
atom interacts with another
similarly excited atom releasing next
photon which is identical in every
respect to the first photon with
same direction of travel
• This phenomenon is called
stimulated emission of radiation
7. Properties of LASER light
• Monochromatic
− A single pure color emitted by a
single wavelength
• Collimated
– A beam in which almost all the
photons are travelling in the same
‘parallel direction’
• Coherent
− Waves travel through space in phase
8. Types of lasers acc. to materials used
• Solid : Nd: YAG laser (neodymium-yttrium aluminum garnet)
• Liquid : Organic dye laser (rhodamin 6G , disodium fluorescein)
• Gas : Helium Neon (He Ne), CO2,Argon and Krypton Gas laser
• Semiconductors : Gallium-Arsenide -Diode laser
• Excited dimer (Eximer Laser) : Argon fluoride and Krypton
fluoride
9. • Infrared light is primarily absorbed by water
• Visible and UV light are absorbed by hemoglobin and melanin
• As wavelength becomes shorter – scatter begins to dominate
the penetration of light
11. Comparison of different types of laser
CO2 Nd: YAG Argon KTP
Wavelength (nm) 10600 1060 488- 514 532
Tissue Absorption High Low Selective
High in
Blood
Selective
High in
Blood
Tissue Penetration 0.1 4 1 1
Coagulation Low High Medium Medium
Cutting effect High Low Low Low
12. Laser reaction to tissues
• When laser radiation strikes a tissue, the temperature begins to
rise
10 0 C – 45 0 C : Conformation change of proteins
50 0 C : Reduction of enzyme activity
60 0 - 99°C : Coagulation begins
100°C and above : Vaporization starts
400 0 -500°C : Char starts to burn
13. Modes of laser
• Continuous : continuously pumped ,emits light
continuously
• Pulse: laser energy delivered with each peak over an
extremely short period of a few nanoseconds with
rest period (allows time for tissues to cool down)
• Q-switched: Allows a high build-up of energy within
the tube which is then released over a very short
duration of a few nanoseconds
15. CO2 Laser
• 10,600 nm wavelength
• Highest power continuous wave laser used for cutting
or ablating tool using water as target chromophore
• Seals blood vessels less than 0.5 mm in diameter
• Pulsed to accommodate thermal relaxation time (less
pain and less edema)
• Used in majority of procedures except those requiring
coagulation of larger vessels
16. • Shallow thermal damage zone (≤ 500 μm)
• Comparatively a poor hemostat (can coagulate blood
vessels < 0.5 mm in diameter)
• Not transmissible through common optical fibre
• Advantage of producing minimal scarring in vocal
cords , therefore glottic competency is rarely
jeopardized
17. Nd : YAG Laser (Neodymium-doped Yttrium
Aluminum Garnet)
• 1064 nm wavelength with Helium-Neon (He-Ne) beam
• Solid state laser with fiberoptic carrier
• Deeper penetration (up to 4 mm) , ideal for ablation,
coagulation and hemostasis in vascular malformations
• Limitations
• Greater scatter than CO2
• Deep thermal injury
• Risk for transmural injury
18. KTP Laser ( Potassium - Titanyl -Phosphate)
• 532 nm wavelength with oxyhemoglobin as primary
chromophore
• Continuous wave (CW) mode to cut tissue
• Pulsed mode for vascular lesions
• Q-Switched mode for red/orange tattoo pigment
• Delivery
• Insulated fiber, fiber handpiece, scanner, or microscope for
CW/pulsed mode
• Articulating arm for Q-Switched mode
19. Helium –Neon Laser
• He-Ne laser emits at 633 nm in the visible spectrum
• Low power laser mainly used as an aiming beam
superimposed on the path of invisible lasers such as
the CO2 or ND:YAG
• Has also been used in wound healing and pain
treatment
20. Argon Laser
• 488 - 514 nm wavelength (Blue green spectrum)
• Oxyhemoglobin is target chromophore
• Small spot size (0 . 1 – 1 mm) , variable in size and intensity
• Flexible delivery system
• Mainly used in ophthalmological procedures
• Limitations
• Also absorbed by epidermal and dermal tissues due to
melanin
• Continuous mode of operation
• Higher prevalence of postoperative pigmentary alteration
and fibrosis
21. Anesthesia for laser airway surgery
• Three major considerations
– Combustion, airway, anesthetic risk
• Combustion
− Risk is greater with a collimated beam such as CO2 laser
and less in lasers that operate in a pulsed mode, as heat can
dissipate between bursts
− Commonly used tubes such as red rubber, latex, and plastics
such as PVC, are easily ignited in a typical anaesthetic gas
mixture, burning with a blowtorch-like flame
22. Management during Anesthesia
• Intubation anaesthesia
− Water is fire retardant as well as being a heat sink,
all swabs and fabric should be wet
− Protection of standard tracheal tubes
• Jet ventilation anaesthesia
• Intermittent apnoeic technique
• Tubeless anaesthesia
23. Indications for LASER In larynx
•Congenital Disorders and benign tumors :
– Laryngomalacia, web, subglottic hemangioma, mucous
cysts, laryngoceles
•Functional dysphonia : plica ventricularis
•Chronic inflammatory conditions
– Reinke’s edema, vocal nodules / polyps, epidermoid cysts
•Excisions for malignancy :
−Carcinoma in situ (CIS) , micro -invasive carcinoma ,
verrucous carcinoma ,management of TIS, T1 and some early
T2 glottic, supraglottic carcinoma
25. Lasers for nasal surgery
• Create relatively bloodless field in endonasal surgery
of the middle meatus complex (MMC)
• CO2 laser is not commonly used in endonasal laser
surgery because of
− Lack of fibre transmissibility
− Poor coagulation and haemostasis
− Increased risk of synechiae formation post
operatively
26. • KTP laser is better in Nasal surgery because
– Fibre transmissible
– Has a high affinity of absorption for pigmented
tissue (hemoglobin)
– Energy conducted into the tissue is well absorbed
by the sinusoidal blood vessels of the turbinate and
results in a coagulation zone with very little
intraoperative bleeding
– Has adequate power for ablation of the bony
framework of the MMC
27. Benefits to the patient from laser technology
in Nose
• Minimally invasive surgery
• Minimal bleeding
• Minimal postoperative edema and crusting
• Ambulatory surgery
• Cost effective
28. Indications of Laser surgery in Nose and PNS
• Reduction of turbinates
• Dacryocystorhinostomy
• Laser-assisted septoplasty
• FESS ( to attain better hemostasis)
− Removal of polyps as a preliminary procedure to FESS
− Excision of the uncinate process, removal of bulla
ethmoidalis, creation of middle meatal antrostomy
− Solitary sphenoid or frontal sinus disease
29. • Miscellaneous
− Rhinophyma
− Recurrent epistaxis
− Telengiectatic, cavernous or pyogenic septal granuloma
− Hereditary haemorrhagic telangiectasia (HHT)
− Choanal atresia or stenosis, nasopharyngeal stenosis,
polyps, adenoid hypertrophy
− Juvenile angiofibroma ,nasopharyngeal cancer
• Any suspicion of orbital, facial, or intracranial extension of the
disease is a contraindication for laser use!!!
30. Laser selection in otology
• CO2, KTP , Argon , Nd: YAG lasers
• In vascular lesions of ear - The Nd: YAG laser, with its
deep scatter, is the laser of choice
• For debulking of tissue : CO2 laser are used
• The visible KTP laser light is well suited for
undertaking temporal bone surgery
− Fibre transmissibility of the KTP beam gives an
added dimension to guide the light around corners
31. Use of Laser in otology
• External auditory canal
– Vascular lesions –haemangiomas ,telangiectasias
– Aural polyps and granulations
– Stenosis of the external auditory canal
– Debulking of large, inoperable EAC carcinoma
– Laser reshaping of cartilage
• Tympanic membrane lesions : Epidermoid cysts
32. • Middle ear cleft
− Laser - assisted myringoplasty
− Graft - welding of tympanic membrane defects
− Laser - assisted ossicular surgery
− Cholesteatoma surgery
− Vascular lesions of the middle ear
− Laser-assisted, totally implantable hearing aids
• Inner ear : Cochleostomy , labyrinthectomy
33. Orofacial Surgery : laser preference
• For vaporisation and cutting in soft tissue, a wavelength such
as carbon dioxide (CO2) modality at 10.6 μm is indicated
• For coagulation in soft tissue, a wavelength which is poorly
absorbed by water but is maximally penetrative is required
(near infrared modality of the Nd: YAG at 1.06 μm)
• For hard tissue such as bone, dentine or enamel,
hydroxyapatite is the chromophore of importance (Erbium:
YAG at 2.9 μm )
34. Use of lasers in Orofacial surgery
• High intensity laser treatment (HILT)
• Oral mucosal premalignant leucoplakia
• Mucosal haemangiomatous lesions of the mouth
• Temporomandibular joint : coagulation of redundant
capsule in recurrent dislocation, pain relief
• Laser hemiglossectomy
• Low intensity laser therapy (LILT)
• Post-herpetic neuralgia , Idiopathic neuralgia
• Intractable ulcerations :Pemphigus vulgaris
35. • Surgery for snoring and obstructive sleep apnea
– Uvulopalatoplasty
– Midline glossectomy
– Linguloplasty
• Laser palatine tonsillectomy
• Laser lingual tonsillectomy
• Cryptolysis for halitosis
36. Laser selection in lower airways
• Most common lasers used : CO2 , Nd:YAG
• CO2 laser: directed towards the lesion through articulated
arm, so used in rigid bronchoscopy, presently used more for
lesions involving the larynx and proximal trachea
• Nd:YAG laser beam can be passed through a flexible
endoscope, which affords deeper penetration, better
coagulation and produces better haemostasis
− Its main disadvantage is the unpredictable interaction of
the laser beam with the tissue, making it difficult to
determine the depth of penetration
37. Lower airway indications
• Laser photoresection of obstructive airway lesions
– Subglottic and tracheal stenosis
– Granulation tissues, broncholith, foreign body, benign
tumours, congenital tracheo- esophageal fistula
• Photodynamic therapy
– Curative therapy for carcinoma in situ, juvenile
laryngotracheobronchial papillomatosis, unresectable
early stage lung cancer palliative treatment for
advanced obstructive lung cancer
38. Hazards of laser
• Damage to biological non-target tissue
− Corneal or retinal injuries, skin and mucosal burns
• Damage to non-biological material
– Anaesthetic tube and draping material
• Side-effects due to laser by-products
− Laser-generated smoke
• Laser malfunction such as electric shock
