Doc. MUDr. Leoš Středa, Ph.D. .
APPLIANCES FOR REGENERATION AND AESTHETIC MEDICINE 6
B82172 •Course in English 1st Faculty of Medicine Charles University
6. SELECTIVE PHOTOTHERMOLYSIS (LASER AND IPL)
Selektivní fototermolýza invazivní lasery a IPL
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Photothermolysis principle and types Tissue heating by photons absorption (pulse light conversion to heat), by laser or intense pulsed light: Power-lasers (invasive): the principle of preferential absorption of electromagnetic radiation in a particular tissue. The laser has a single wavelength, the action is limited to specific chromophores IPL: wide range of wavelengths allows for more extensive range of display, simultaneous action on various skin disorders at the same time •4
Invasive Lasers in Aesthetic Medicine Monochromatic single wavelength radiation of power lasers. It affects so called tissue chromophores. These are the molecule parts responsible for absorption of electromagnetic radiation (light). When chromophore is illuminated by light of specific wavelenght, chromophore absorbs it and changes its status.
Chromophores  hem is hemoglobin chromophore, its
absorption coefficient is in the range 500-600 nm - suitable for e.g. argon , ruby or alexandrite lasers  melanin chromophores, absorption coefficient is in range 400-720 nm - suitable for example, argon, KTP (potassium-titaniumphosphate) lasers
Invasive lasers applications (1) 1. Epilation lasers (1)  Method inaccurately presented as a method of permanent hair removal. Like other epilation techniques (electrocoagulation, electrolysis, high-frequency hair removal or IPL) does not cause PERMANENT hair removal. A more accurate statement is that it is a permanent reduction of hair. Permanent hair reduction is defined as a significant loss of hair, which is quantitatively stableover for longer period than the hir growth cycle. •7
Invasive lasers applications(2) 1. Epilation lasers (2) Target tissues: melanin in the hair follicle. Phototermolysis destroys dermal papilla cells. Since hair are at different stages of hairgrowth treatment should be repeated several times. The best effects are achieved with dark hair. •8
Invasive lasers applications(3) 2. Vascular lesions are treated with lasers, whose absorption maximum is in hemoglobin. Vessel coagulation occurs .  Cosmetic indications: telangiectasiae, varices , also other lesions such as verrucae vulgares, hyperplastic and keloid scars •9
Invasive lasers applications(4) Pigmented lesions and tattoos removed by photodisruption (rozstřelení) of melanin or tattoo pigment, which is subsequently phagocytosed. These are lasers have a high pulse energy. Cosmetic indications: age spots, postinflammatory hyperpigmentation, hyperpigmented scars. Indications for laser tattoo removal depends on the type of dye that was used. •10
Invasive lasers- summary Laser light is monochromatic and coherent. This
allows to focus the laser beam to a small area and achieve a power density, which allows to use a laser to invasiveprocedures as a surgical tool in aesthetic surgery. The laser beam can be aimed by mirrors, lenses or optical fibers. Photons are absorbed in the surface layer of tissue. Thermal effects (thermolysis) depend on the power density of light and its wavelength. Nonthermal effects are typical for soft-lasers, almost undepend on the wavelength.
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IPL – Intense Pulsed Light
Light with a biological effect similar to laser thermolysis. From the physical point of view, is used polychromatic and incoherent light. •12
IPL characteristics polychromatic light incoherent
low energy density pulse character there is no risk of eye lens focusing the beam funwanted wavelengths filtered out
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Principle of Effect (1) Photothermolysis by short flashes of high
intensity polychromatic incoherent light. This effect is achieved by xenon lamps direct application. IPL devices operating principle is based on the accumulation of electrical energy in the capacitor electric circuits (kondenzátorový elektrický okruh).
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Principle of Effect (2) The light flash lasts few miliseconds, with
modern equipment even less. It can be repeated at regular intervals with fast breaks of the same length as was the flash. Shortflash duration prevents contact with the surrounding tissue and contributes to the targeted activity.
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Principle of Effect (3) The main absorber of light energy is melanin.
Absorbed light increases skin temperature, which carries the risk of epidermis damage. Selective target on specific structures is achieved by a combination of light pulses of different lengths, delays between them, which allows tissue cooling.
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Cut off filters for IPL To filter out ultraviolet (UV) spectrum is
used sapphire crystal filter or quartz (křemnné) or borosilicate glass. For a particular indications is necessary to filter out the also the wavelengths, that are not needed for the selected application, cutoff filters.
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Targeted effect Tissues heating selectively based on their color. IPL targets the basic physiological dyes. - pigment melanin during epilations (targeted are melanosomes in keratinocytes) - pigment melanin during removing of the melanin spots and hyperpigmentations (melanosomes in melanocytes) - pigment hemoglobin in vascular lesions •18
Effect rules melanin absorption decreases with
increasing wavelength hemoglobin absorption has several peaks in the visible and NIR range (near infrared - it is the closest spectrum below the red color with a wavelength range from 760 to 1400 nm).
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Surrounding tissue protection Cooling: 1. length of delay between pulses 2. water circulation in the manual applicator 3. cooling gels application - it has a special benefit in dispersion minimizing and therefore energy density (H, fluency) is not lowered. Targeted total energy per unit area (J.cm-2) is improved. •20
General application rules Criteria: 1. skin phototype 2. type of lesion 3. lesion size
Modern devices set all automatically
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Fitzpatrick phototypes range 6 phototypes according to the quality of individual response to sunshine effect 1-lightest 6-blacks Central Eruropeans are usually 2-3 •22
Type of lesion decides which dye should be targeted by
IPL. Usually target is melanin or hemoglobin. The type of dye implies a choice of suitable wavelength. Shorter wavelengths are chosen in superficial (surface) applications. In-depth applications are suitable for longer length •23
Lesion size Smaller targets are cool faster than bigger ones. Cooling time is inversely proportional to the square of the size of the targeted lesion. Not only the size is critical, but the concentration of pigment is also important.
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Cosmetic indications unwanted hair epilation (wavelength 650 nm), skin rejuvenation
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Dermatological indications vascular lesions (e.g. telangiectasia removal) pigmented lesions (e.g. Hyperpigmentation or tattoo removal reduction of acne and rosacea symptoms reducing psoriasis symptomd poikilodermie signs reducing (skin atrophy with pigment changes)
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Photoepilation IPL for hair removal is being called Photoepilation Laser hair removal - Laser epilation.
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Photoepilation (2) IPL penetrates through the skin into the hair follicle, where light energy converts into heat . Difuse melanin in the epidermis is affected by the heat below the heat damage level. In hair follicles, where melanin is concentrated in larger units, it will warm up tissue to temperature of 70 to 75º C. This temperature denatures the molecule, it destroys hair follicle including hair. •28
Photoepilation (3) The highest concentration of melanin in the hair is in the anagen growth phase. In this phase there are usually 85% of all hair. Anagen phase persists for several years. several years.IPL has the thermolytic effect on hair in this phase, while in subsequent stages (katagen and telogen) effects only minimally.
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Photoepilation (4)  Before photoepilation all growth hair has to
be shaved. Don´t pull them off as they have to be point of conversion of light energy into heat inside the hair follicle due to melanin content. Photoepilation can be applied all over the body. The most commonly it is used for hair removal in the crotch(the bikini line), armpits and often in the face.
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Photoepilation (5) Photoepilation brings the best results : if there is strong contrast between lighter skin and dark hair If skin is not dark or tanned If hair is dark if skin is without hyperpigmentation Photoepiltion is ineffective in white, blond and ginger hair
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Photoepilation (6) unwanted side effect burns
Post-epilation skin hypopigmentation whitening hair (leukotrychie)
folliculitis paradoxical hypertrichosis skin ulceration
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Photorejuvenation Photorejuvenation- intense pulsed light (IPL) or soft laser to achieve full effect on the appearance of skin rejuvenation. Resurfacing – invasive rejuvenation of skin by high-power lasers (such as erbium or CO2 laser), ablative surgery, which removes the top layer of skin.
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Photorejuvenation (2) Comprehensive treatment - IPL effects in several factors simultaneously. 1.rebuilding skin structures, particularly collagen and elastin in the dermis 2.teleangiectasiae and pigment spots removal causes the effect of skin color uniforming and brightening of skin appearance. •34
Photorejuvenation (3)  Synonymum is
non-ablative dermal remodeling.  The primary effects: intense pulsed light thermally breaks and destroys the elastic fibers in the upper dermis, causing subsequent fibroplazia and the development of new intercellular substance stimulation
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Autor: Leoš Středa
Selektivní fototermolýza Invazivní Lasery IPL
POSLEDNÍ REVIZE: BŘEZEN 2012 •36