APPLIANCES FOR REGENERATION AND AESTHETIC MEDICINE 6

Doc. MUDr. Leoš Středa, Ph.D..

B82172

•Course in English

1st Faculty of Medicine Charles University

6. SELECTIVEPHOTOTHERMOLYSIS(LASER AND IPL)

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Selektivní fototermolýza invazivní lasery a IPL

Photothermolysis principle and types

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Tissue heating by photons absorption (pulse light conversion to heat), by laser or intensepulsed light:

Power-lasers (invasive): the principle of preferential absorption of electromagneticradiation 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

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 range500-600 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-titanium-phosphate) lasers

Invasive lasers applications (1)

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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 forlonger period than the hir growth cycle.

Invasive lasers applications(2)

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1. Epilation lasers (2)

Target tissues: melanin in the hair follicle.Phototermolysis destroys dermal papillacells. Since hair are at different stages of hairgrowth treatment should be repeated several times.

The best effects are

achieved with dark hair.

Invasive lasers applications(3)

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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

Invasive lasers applications(4)

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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, post-inflammatory hyperpigmentation, hyper-pigmented scars. Indications for laser tattoo removal depends on the type of dye that was used.

Invasive lasers- summary

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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. Non-thermal effects are typical for soft-lasers, almost undepend on the wavelength.

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.

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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 berepeated 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 thetargeted 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, cut-off filters.

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Targeted effect

Tissues heating selectively based on their color. IPL targets the basic physiologicaldyes.

- 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

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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.

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General application rules

Criteria:1. skin phototype2. type of lesion3. 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-lightest6-blacks

Central Eruropeans are

usually 2-3

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Type of lesion

decides which dye should be targeted by IPL. Usually target is melanin or hemoglobin. The type of dye implies a choiceof suitable wavelength.

Shorter wavelengths are chosen in superficial (surface) applications.

In-depth applications are suitable for longer length

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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 concentratedin larger units, it will warm up tissue to temperature of 70 to 75º C. This temperaturedenatures the molecule, it destroys hair follicle including hair.

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Photoepilation (3)

The highest concentration of melanin in the hair is in the anagen growth phase. In thisphase 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 byhigh-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.

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Photorejuvenation (3)

Synonymum isnon-ablativedermal 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 substancestimulation

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POSLEDNÍ REVIZE:

BŘEZEN 2012

Autor:

Leoš Středa

Selektivní fototermolýza

Invazivní Lasery

IPL