Laser

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 08.02.2021

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Synonym(s)

Carbon dioxide laser; dermatological lasers; dermatological laser therapy; Dye Laser; Laser therapy; Light Amplification by Stimulated Emission of Radiation

Definition
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Acronym for "Light Amplification by Stimulated Emission of Radiation". By stimulated emission of radiation, a coherent amplification of electromagnetic oscillations takes place, producing bundled, monochromatic, high-energy light with high intensity and good focusability. The active medium of the laser can be solids (e.g. ruby crystals), liquids (dye solutions, e.g. Rhodamine 6G or gases (e.g. argon,CO2).

General definition
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  • Lasers can emit their energy continuously (continuous wave -cw-) or in pulses (pulsed lasers). Pulsed lasers produce light flashes in the microsecond range. Extremely short exposure times and very high powers can be achieved by a quality switch (qs-).
  • Medically important lasers (wavelengths emitted in brackets):
    • Alexandrite laser (755 nm): The quality switchedalexandrite laser is used to treat tattoos and pigmented skin lesions. The mode of action and side effect rate are similar to the ruby laser.
    • Argon laser (488 nm): used since 1975 mainly for the treatment of vascular changes of the skin and superficial pigmentary changes. The light of the argon laser can penetrate about 1 mm deep into the skin. The absorbed energy closes the vessels or destroys the pigmented cells. The risk of scars and colour changes is higher than with the dye laser.
    • CO 2 laser (10,600 nm): Ablative laser, suitable for "skin resurfacing", for smoothing acne scars, but also for ablation of xanthelasma and syringoma. The principle ofCO2 laser treatment is based on the vaporization of the uppermost skin layers. The energy of the laser impulses is absorbed by water-containing cells and converted into heat.
    • Diode laser (mainly 805-810 nm): Laser specially designed for epilation (photoepilation). Diodes (semiconductors) are used as the light source.
    • Erbium YAG laser (2,940 nm): Ablative laser with a similar range of application toCO2 lasers. Compared to the carbon dioxide laser, it develops less heat (cold ablation). The treatment is therefore less painful and the treated skin heals more quickly. The disadvantage of this type of laser is that due to the lack of heat development, there is no collagen shrinking and no hemostasis. The smoothing effect is therefore somewhat less.
    • Erbium glass laser (1,535-1,550nm): Fractionated non-ablative laser. This is used for the treatment of moderately pronounced wrinkles, benign pigmentation, scars and coarsely porous skin. The mechanism of action is based on localized dermal heating followed by remodeling. Skin types I-VI can be treated. This laser is contraindicated for keloids and hypertrophic scars. Multiple treatments at 4-6 week intervals are required to produce moderate improvement in photo-aged skin and wrinkles.

    • Excimer laser (308 nm): Primarily used to treat individual psoriatic plaques in chronic stationary psoriasis vulgaris due to the emission spectrum.
    • Dye laser (585-600 nm): The pulsed dye laser can be used to remove nevi flammei, senile angiomas and nevi aranei. The effect is based on the principle of so-called selective photothermolysis. The light of the laser is absorbed by pigment-rich structures and converted into heat. This heat selectively damages or destroys the respective target structure. Target structures of the dye laser include small skin vessels, e.g. spider veins.
    • Neodymium YAG laser (QS: 532 nm; pulsed 1064 nm): The long-pulsed Nd-YAG laser is particularly suitable for the therapy of vascular changes. In the case of nodular nevi flammei and thick or deep-lying haemangiomas, a thin light guide is introduced into the tissue, thus enabling treatment in depth. The light from the Nd-YAG laser is absorbed by the blood cells. These stick together and close the vessels. Tattoos can be removed very well with the Q-switched Nd-YAG laser.
    • Ruby laser (694 nm): The Q-switched ruby laser is particularly suitable for removing tattoos, dirt particles, permanent make-up and benign pigmented skin changes. The light of the ruby laser is absorbed by melanosomes, which are destroyed by it. An inflammation occurs, which attracts macrophages. These take up the color particles and transport them away. Further color particles are removed by the healing of the crusts that form on the treated areas. For permanent epilation, the long-pulsed ruby laser is used.
  • Flash lamps (250-1200 nm): A technology similar to laser is the flash lamp technique (IPL technique). Its primary field of application is diffuse erythema due to telangiectasia. Also suitable for photoepilation. IPL light is emitted e.g. by a xenon lamp.

Note(s)
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For the dermatological laser therapy the analogous fee items No. 2440 GOÄ (< 7.0 cm²) No. 2885 GOÄ (7 cm² - 21 cm²) or 2886 GOÄ (> 21 cm²) are used depending on the extent of the areas to be treated. It is not important how many of the above-mentioned skin changes are treated and with which laser method. Only the extent of the area as a whole is to be evaluated. If, for example, verrucae vulgaris with an extension of about 18 cm², as well as further verrucae with an extension of 4 cm² are treated by laser in one session, the analogous no. 2886 GOÄ can be calculated.

Literature
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  1. Almirall,Herrmal (2014) Business letters dermatology 10:7
  2. Basov NG, Prokhorov AM (1954) 3-level gas oscillator. Zh Eksp Teor Fiz (JETP) 27: 431
  3. Gordon JP, pointer HJ,Townes CH (1955) The Maser. New type of amplifier, frequency standard and spectrometer. Physiol Rev 99: 1264-1274
  4. Greve B, Raulin C (2003) Medical dermatological laser therapy: An overview. dermatologist 54: 594-603
  5. Hohenleutner U et al (1995) Ruby laser: Medicine or cosmetics? Z Hautkr 70: 875-876
  6. Kaufmann R (1992) Current status and new trends in dermatological laser therapy. Z Hautkr 67: 495-502
  7. Kimmig W (2003) Laser interventions in dermatology: risks and opportunities. dermatologist 54: 583-593
  8. Raulin C (1996) Possibilities and limitations of the pulsed dye laser. Z Hautkr 71: 96-102
  9. Stratigos AJ, Dover JS, Arndt KA (2003) Laser therapy in aesthetic dermatology. Dermatologist 54: 603-613

Tables
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Laser type

Wavelength

Pulse duration

Energy

Pulse rate

Performance

Applications

Alexandrite laser

755 nm

up to 40 ms

50J/cm2

10 Hz

removal of tattoos, epilation, hyperpigmentation

Argon laser

488 nm and 514 nm

up to 5 W

Haemangiomas, senile angiomas, N. flammeus, telangiectasias

Diode laser

805 (635-900) nm

up to 100 ms

up to 60 J/cm2

to 2 Hz

1600 W

Epilation

Excimer laser

308 nm

8 ns

10 mJ

up to 200 Hz

50 mW

Vitiligo, psoriasis vulgaris and other inflammatory dermatoses

CO2 laser

10.600

< 1.4 ms

1-500 mJ

1-100 W

cutting ( scalpel ), vaporizing, material processing

Ultrafine Encore Laser

< 2 ms

1-250 mJ

1-60W

laser peeling, skin resurfacing, blepharoplasty

Ruby laser

694 nm

40 ns to 2 ms

10-500 mJ

1-5 Hz

100 W

removal of tattoos, pigmentation disorders

Nd-YAG laser

Qs: 532 nm

4-5 ns

200 mJ

up to 10 Hz

5-100 W

vascular diseases, removal of tattoos (red, yellow, orange), hypertrophic scars

pulsed: 1064 nm

5-6 ns

400 mJ

up to 10 Hz

5-100 W

Tattoo removal, coagulation, cutting ("bare fiber")

pulsed dye laser

585-600 nm

500 µs or 1500 µs

up to 20 J/cm2

2-9 kW

Nevus flammeus

Erbium-YAG

2940 nm

100-400 µs

0,1-2 J

up to 33,3 Hz

up to 20 W

Lentigines, actinic keratoses, flat seborrhoeic keratoses, milia

Authors

Last updated on: 08.02.2021