What is laser; Its uses in dermatology; Types of lasers; Treatment options for acne scars, melasma; hyper pigmentation; wrinkles; warts; Dark skin, facial rejuvenation; stains; rosacea; hair removal options;
“LASER” is an acronym that stands for Light
Amplification by the Stimulated Emission of
Laser is an instrument that generates a beam of
light of a single wavelength or color that is both
highly collimated and coherent.
• The first functional laser (ruby, 694 nm) was
developed by Maiman in 1960.
Characteristics of Laser Light:
Monochromatic: composed of a single wavelength or color.
Coherence: All the waves of light move together temporally and
Collimation: where the transmission of light occurs in parallel fashion
without significant divergence, even over long distances.
Lasers Commonly used in Dermatology:
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
Power: The rate at which energy is emitted from a laser.
Joule (J): A unit of energy used to describe the rate of
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.
Pulse: A discontinuous burst of laser as opposed to a
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.
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.
Thermal Relaxation Time(TRT): time required for the
dissipation of 63% heat gained by the tissues (ms/μs) during
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
Chromophores in the Skin:
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.
Classification of Lasers:
Laser are classified according to the nature of the amplifying
medium: gas, liquid(dye) or solid state:
Modes Of Output:
• Continuous wave
• Quasi CW
Ablative Vs Non Ablative:
ABLATIVE: outer layers of skin are (removed) through
vaporization of the cells. Healing takes place by re-deposition
NON-ABLATIVE: induce dermal neocollagenesis without
Laser beam is “fractionated” into a pattern where some parts
of the skin are targeted, and the other parts are left intact. A
grid like pattern appears on the skin.
• 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
Target molecules are called chromophores:
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.
1)Photostimulation: Low energy lasers expedite wound
2. Photodynamic change: uses topical or systemic
photosensitizers. Subsequent irradiation elicits a photo-
oxidative reaction and an immediate cytotoxic effect.
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,
Contact skin cooling
Copper, or sapphire tips:
For delivering longer pulse durations(>10 ms)
Provide pre, parallel and post laser cooling.
Reduces inflammation post procedure.
Disadvantages: a waiting period
Melting water on the skin
Not advised nowadays.
Cannot provide prolonged cooling.
Non Contact Cooling:
1) Cryogen spray (liquid nitrogen):
(a) Not recommended now causes
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
(b) By convection cooling.
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)
• Tendency to keloid scarring.
• Personal or family history vitiligo.
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
Topical anesthetic ointment under occlusion for 1 hr.
For ablative procedures, nerve blocks, tumescent anesthesia.
• Active bacterial,viral or fungal infections
• Unrealistic expectations
• Uncooperative pts
• 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).
The operating room:
• 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.
Safety measures for the patient:
• Special glasses should be used.
• Patient Consent
• The surgeon should use the special glasses for the
• NEVER look directly into the laser source.
• NEVER point the hand probe in any direction, except
towards the area to be treated.
SKIN CARE INSTUCTIONS AFTER LASER SURGERY:
• 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
Side Effects of Lasers:
• Pain, burning sensation, edema
• Oozing, crusting
• Secondary infection
• Reactivation of HS infection
• Dyspigmentation (hypo/hyper)
• Change in skin texture
• Demarcation lines
(in facial rejuvenation)
• Keloids and hypertrophic scars
• Persistent erythema
• Dilated follicular ostia
Nd: Yag Laser:
Nd:YAG (neodymium-doped yttrium aluminum garnet) is used
as a laser medium.
• Wavelengths: 532nm and 1064 nm,
• Penetrates 2-3mm into dermis
Has the least absorption by melanin
Effective for both epidermal and dermal pigmented lesions.
Is well absorbed by both melanin and hemoglobin.
Has superficial penetration,
Limited to treating epidermal pigmented lesions.
Spider and thread veins
Nevus of Ota and Ito
Pulsed Dye Laser:
• 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
• Primary chromophore: hemoglobin.
Carbon Dioxide Lasers:
Active laser medium:
10–20% carbon dioxide,
Exists as Ablative nonfractinated laser
Ablative fractinated laser
Wavelength: 10,600 nm
Primary chromophore: Water
• Depth: 20-30 µm of skin (epidermis and superficial
• In the healing period: re-epithelialization
The following skin disorders can be treated with carbon
dioxide laser beams:
• Acne scars
• Varicella and smallpox scars
• Verruca vulgaris/plana
• Junctional & compound Nevi
• Small syringomas