BASICS OF LASERS

1. BASICS OF
LASER

2. “LASER”isanacronym that stands for Light
Amplification by the Stimulated Emission of
Radiation.
Laser is an instrument that generates a beam of light of a
single wavelength or color that is both highly collimated
and coherent.
DEFINATION

3. Principle of Laser

4. BASICS COMPONENTS OF LASER

5. • The first functional laser (ruby, 694 nm) was
developed by Maiman in 1960.
HISTORY

6. Monochromatic: composed of a single wavelength or color.
Coherence: All the waves of light move together temporally and
spatially.
Collimation: where the transmission of light occurs in parallel
fashion without significant divergence, even over long distances.
Characteristics of Laser light

7. Electromagnetic Spectrum :

8. 1. Argon Laser: 488/514 nm
2. Potassium-titanyl-phosphate (KTP): 532 nm
3. Copper bromide/vapour: 510/578 nm
4. Argon-pumped tunable dye (APTD): 577/585 nm
5. Krypton: 568 nm
6. Pulsed dye laser (PDL): 585/595 nm
7. QS ruby: (694 nm)
8. QS alexandrite: (755 nm)
9. QS neodymium (Nd):yttrium-aluminum-garnet
(YAG): 1064 nm
10.Erbium:YAG: 2940 nm 11.Carbon
dioxide Laser: 10,600 nm
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Lasers Commonly Used in Dermatology

10. Power: The rate at which energy is emitted from a laser. Watts.
Joule (J): A unit of energy used to describe the rateof energy
delivery.
Fluence: determines the amount of laser energy per unit area
and is expressed in joules/cm2.
Spot Size: The mathematical measurement of the radius of the
laser beam.
Terminology

11. Pulse: A discontinuous burst of laser as opposed to a continuous
beam.
Pulse Frequency: The rate at which pulses are generated. Is
expressed in pulses per second (Hz).
Pulse Duration: The "on" time of a pulsed laser. Measured in
terms of ms, μs, or ns.

12. Irradiance: (power density) The rate at which energy is delivered
per unit area.
It determines the ability of a laser to incise, vaporize, or
coagulate tissue and is expressed in watts/cm2.

13. Thermal Relaxation Time(TRT): time required for the
dissipation of 63% heat gained by the tissues (ms/μs) during
irradiation.
Thermal Damage Time(TDT): The time for the entire target
including the primary chromophore and surrounding target to cool
by 63%.
Focus: The exact point at which the laser energy is at peak power
63
%

14. Are the selectively laser energy absorbing target molecules in
the skin.
1. Endogenous chromophores:
• Melanin: UV -1200nm
• Hb: UVA, blue (400 nm), green (541 nm), Yellow (577nm)
• Collagen: Visible and near infra-red spectra
• Water: in the mid and far infrared regions
2. Exogenous chromophores: Such as tattoo ink.
Chromophores in the Skin

15. Laser are classified according to the nature of the amplifying
medium: gas, liquid(dye) or solid state:
Classification of Lasers

16. • Continuous wave
• Quasi CW
• Pulsed
Modes of Output

17. ABLATIVE: outer layers of skin are (removed) through
vaporization of the cells. Healing takes place by re-deposition of
collagen.
Egs:
Er: YAG
CO2 laser
NON-ABLATIVE: induce dermal neocollagenesis without
epidermal disruption,
KTP
Pulsed Dye
Nd: YAG
Ablative Vs Non Ablative

19. Laserbeam is “fractionated” into apattern where someparts of the
skin are targeted, and the other parts are left intact. A grid like
pattern appears on the skin.
FRACTIONATED LASER

20. How Fractionated Lasers Work

21. Tissue Optics

22. 1. Reflection.
• 4–6% of light is reflected.
• Lowest when the beam is perpendicular.
2. Absorption. Depends on the properties
of the substance through which the light
passes.
Target molecules are called chromophores:
(1) Melanin
(2) Hemoglobin
(3) Water
(4) Collagen
Tissue Optics :

23. 3.Scattering. Is the deviation of light by non-
uniformities in the medium
Eg: collagen in the dermis.
It reduces the energy available for the
target chromophores.
4.Transmission. Light that is not
Reflected, absorbed or scattered
passes to deeper tissue.

24. 1) Photostimulation:Low expedite wound energy lasers
healing.
Light-Tissue Interaction

25. 2. Photodynamic change: uses topical or systemic
photosensitizers. Subsequent irradiation elicits a photo-
oxidative reaction and an immediate cytotoxic effect.

26. 3) Photo-thermolytic and Photo-mechanical Effect: works on
the principal of Selective photothermolysis: A concept used to
target chromophore based:
• on its absorption characteristics,
• the wavelength of light used,
• amount of energy delivered.
• the duration of the pulse,

27. 4.Photo Acoustic Effect

28. Uses of Laser: Lasers
1. Hair Reduction:
Chromophore: Melanin
Long pulsed Nd:Yag
(1064nm)
Alexandrite laser (755nm)
2.
Hyperpigmentation:
Chromophore: Melanin
(a) Epidermal Type Q switched, Nd:Yag
(532nm)
PDL
(b) Dermal Type: Q switched Nd:Yag
Uses of Lasers:

29. 3. Vascular Lesions:
Chromophore: Hemoglobin
(a) Port wine stain PDL
Alexandrite laser (755nm)
Q switched Nd:Yag
(1064nm)
(b)Small calibre
Telengiectasia
PDL
(c) Large Vessel
Telengiectasia
Krypton Laser (568nm)
Copper vapour Laser

30. (4) Facial
Rejuvenation:
(a)
Ablative:
CO2
laser(10,600nm)
Erb:Yag laser (2940nm)
(b) Non-Ablative:
PDL
Q-switch Nd:Yag
(1064,532)
(5) Hypertrophic scars, warts,
PD
L benign neoplasm
(7)
Acne
PD
L
(6)
Hemostasis
CO2 Laser
(10600nm)
(7) Laser
Lipolysis:
Nd: Yag Laser
(1064nm)
Chromophore:
Water

31. (8)
Tattoos:
(b) Green
(c) Red/ Orange/ Purple
Q-switched ruby,
Q-switched alexandrite
Q-switched 1064-nm Nd:YAG
Q-switched ruby,
Q-switched alexandrite
Q-switched Nd:YAG 532-nm
Chromophore: Tattoo Ink
(a) Blue/ Black

32. Cooling Systems

33. Contact skin cooling
• Active
Copper, or sapphire tips:
For delivering longer pulse durations(>10 ms)
Provide pre, parallel and post laser cooling.
• Passive
Ice cubes:
Reduces inflammation post procedure.
Easy method.
Disadvantages: a waiting period
Melting water on the skin
Aqueous gels:
Not advised nowadays.
Cannot provide prolonged cooling.
Cooling Systems

34. 1) Cryogen spray (liquid nitrogen):
(a) Not recommended now causes
cryonecrosis.
2) Pulsed cryogen spray (dynamic cooling
device):
(a) Provides uniform cooling at -30C
(b) Method of choice
3) Forced refrigerated air:
(a)Delivers chilled air pre, parallel and
post procedure.
(b) By convection cooling.
Non Contact Cooling:

35. Preparing A Patient for
Laser Session:

36. 1. Take History to find out:
• Immunocompromised status, esp diabetes
• Isotretinoin use.
• Active local or systemic infections especially recurring HS
infection. (Aciclovir or valaciclovir given 1 day prior to &
5–14 days post treatment)
• Tendencyto keloid scarring.
• Personal or family historyvitiligo.
2. Prophylactic antibiotics and antivirals for ablative procedure
3. To minimize post laser hyperpigmentation: 2 weeks
before and 8 weeks after laser:
0.2% Retinoid preparation
2% Hydrocortisone
4% Hyroxyquinone
Anesthesia:
Topical anesthetic ointment under occlusion for 1 hr.
Patient Selection

37. Absolute:
• Active bacterial,viral or fungal infections
• Unrealistic expectations
• Uncooperative pts
• Malignancy
Relative:
• Immunocompromised: Diabetes, HIV, Hepatitis B,C
• Oral isotretinoin
• Fitzpatrick skin 5-6 phototypes
• History of keloids.
• Patients taking gold salts are at the risk of chrysiasis (gold-
related skin discoloration).
Contraindications:

38. Precautions:

39. • Laser room should be properly labeled.
• Hang eye goggles on the door.
• Unauthorized people should not be allowed.
• The room should not contain volatile substances such as
ether, alcohol .
• Plume evacuator: for larger lesions and warts.
Precautions:
The Operating Room:

40. • Special glasses should be used.
• Patient Consent
• The surgeon should use the special glasses for the
particular laser.
• NEVER look directly into the laser source.
• NEVER point the hand probe in any direction, except
towards the area to be treated.
Safety measures for the Patient:
General measures:

41. • Do not rub, scratch or put pressure on the treated area
• Do not apply make-up in case of severe reaction.
• Avoid sunlight; Sun blocks can be advised.
• Ice bags to alleviate erythema and edema.
• Emollients to keep skin moist.
• Avoid irritants to the resurfaced areas
• Erythema and edema settle with topical corticosteroids
SKIN CARE INSTRUCTIONS AFTER
LASER SURGERY:

42. SIDE EFFECT OF LASERS:

43. (1) Immediate:
• Pain, burning sensation, edema
(2) Early:
• Oozing, crusting
• Secondary infection
• Reactivation of HS infection
Side Effects of Lasers:

44. (3) Late:
• Dyspigmentation (hypo/hyper)
• Change in skin texture
• Demarcation lines
(in facial rejuvenation)
• Keloids and hypertrophic scars
• Scarring
• Milia
• Persistent erythema
• Dilated follicular ostia

45. Nd:YAG (neodymium-doped yttrium aluminum garnet) is used as a
laser medium.
• Wavelengths: 532nm and 1064 nm,
• Penetrates 2-3mm into dermis
QSNd:YL 1064-nm:
Has the least absorption by melanin
Deepest penetration.
Effective for both epidermal and dermal pigmented lesions.
QSNd:YL 532-nm:
Is well absorbed by both melanin and hemoglobin.
Has superficial penetration,
Limited to treating epidermal pigmented lesions.
Nd:Yag Laser:

46. Spider and thread veins
Varicose veins Telangiectasia
Haemangioma
Solar lentigines
Freckles
Nevus of Ota and Ito
Mongolian spot
Café-au-lait-macules.
Vascular Lesions:
Pigmented Lesions:

47. Hair Removal:
Tattoos:

48. • Contains a rhodamine dye
• Wavelength: 585–600 nm.
• Pulse duration:0.45 ms (short-pulse)
1.5–40 ms (long-pulse PDL)
• Penetrates the dermis to a depth of 1.2 mm &
photocoagulates vessels of up to 100 μm in diameter.
• Primary chromophore: hemoglobin.
Pulsed Dye Laser:

49. • Port wine stains
• Superficial hemangioma
• Telangiectasia
• Plane warts
• Pyogenic granuloma.
• Melasma
• Hypertrophic scars
• Nail psoriasis/plaque psoriasis
USES:
Cutaneous Vascular
Lesions:
Non-Vascular Skin conditions:

50. Active laser medium: 10–
20% carbon dioxide,
Exists as Ablative nonfractinated laser
Ablative fractinated laser
Wavelength: 10,600 nm
Primary chromophore: Water
Carbon Dioxide Lasers:

51. • Depth: 20-30 µm of skin (epidermis and superficial
papillary dermis)
• In the healing period: re-epithelialization

52. The following skin disorders can be treated with carbon
dioxide laser beams:
• Rhytides
• Acne scars
• Varicella and smallpox scars
• Verruca vulgaris/plana
• Junctional & compound Nevi
• Small syringomas

53. THANK YOU