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Laser hair removal

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Laser hair removal

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    1. Laser hair removal

    2. Target structure for hair removal Hair shaft Stem cell in bulge Hair matrix in hair bulb

    4. Level of hair destruction Destroy hair shaft without germinative area injury : hair shaft fall out : hair regrow to normal anagen cycle

    5. Level of hair destruction (cont.) Partial germinative area injury : hair cycle dysfunction : thinner and finer hair Total germinative area injury : long term hair loss

    6. Permanent hair reduction Significant long term, stable reduction in number of terminal hair Maintain hair reduction for 6-12 month E.g. laser, IPL

    7. Permanent hair removal Reduction of regrowing hair E.g. electrolysis

    8. Electrolysis hair removal Galvanic Thermolysis Combine

    9. Galvanic electrolysis Direct electric current to hair follicle through inserted needle Current produce sodium hydroxide that destroy hair bulb and dermal papilla Most effective but slowest

    10. Thermolysis High frequency alternating current produce heat to follicular tissue Destruction of hair bulb Quick but not effective in thick or highly curved hair

    11. Laser hair reduction Selective photothermolysis Target chromophore :Melanin lie in hair shaft and bulge of follicle :Reproducing cell in bulge, bulb Ideal candidate : dark, coarse hair Ideal candidate : dark, coarse hair

    12. Laser hair reduction (cont.) End point : vaporization of hair shaft : follicular erythema and edema 3-6 session, 1-2 month apart 20-30% reduction per session 70-80% long term reduction

    13. Mechanism of laser hair reduction Photothermal destruction Photomechanical destruction Photochemical destruction

    14. Photothermal destruction Deep, selective heating of hair shaft, hair follicle epithelium, heavily pigmented matrix Thermal conduction from melanin rich shaft and matrix will heat surrounding follicular structure

    15. Photomechanical destruction Small local explosion Extremely rapid heating chromophore Damage individual pigment cell in hair follicle

    16. Photomechanical destruction (cont.) Very short pulse generate photoacoustic shock wave that cause focal photomechanical disruption of melanocyte in bulb but no complete follicular disruption leading to leukotrichia but not to hair loss

    17. Photochemical destruction Use light and photosensitizer to produce target photochemical reaction and therapeutic effect Singlet oxygen is a potent oxidizer that damage cell membrane and protein Effective in treating non-pigment hair

    18. Photochemical destruction (cont.) Photosensitizer : ALA, other porphyrin, chlorin, phthalocyanine, purpurin

    19. Type of laser hair reduction Photothermal destruction : normal mode ruby laser : normal mode alexandrite laser : pulsed diode laser : long pulsed Nd:YAG laser : IPL

    20. Type of laser hair reduction (cont.) Photomechanical destruction : carbon suspension Q-switch Nd:YAG laser : Q-switch Nd:YAG laser Photochemical destruction : photodynamic therapy

    21. Factor to consider laser hair reduction Hair color, density and texture : white, fine, very blonde hair not remove by laser Skin type Anatomical location

    22. Patient preparation No plucking, waxing 6 wk. prior to treatment Shaving, bleaching, chemical depilatories not interfere laser treatment Avoid sun tan

    23. Clinical improvement Absolute hair number reduction Finer, lighter regrowing hair Slower regrowth

    24. Ruby laser (694 nm) Indicate for light skin (type 1-3) with dark hair Penetrate less deeply (2 mm) Laser not effectively reach to hair bulb Miniaturization of follicular bulb and papillae

    25. Ruby laser (cont.) Reduce number of terminal hair Increase small vellus like hair No evidence of fibrosis or destruction of hair follicle No longer used

    26. Alexandrite laser (755 nm) For skin type 1-3 Penetrate deeply enough to affect the growth center of hair Best of choice for light or very fine hair Side effect : hypo or hyperpigmentation

    27. Alexandrite laser (cont.) Report of paradoxical hypertrichosis after alexandrite that common in young female, skin type 3-6 with fine dark hair on lateral face

    28. Diode laser (800 nm) For all skin type More safely than ruby and alexandrite laser in darker skin type Deeper penetration but slightly less melanin absorption Optimal for coarse, dark terminal hair

    29. Long pulse Nd:YAG laser Minimal absorb by melanin, so high fluence to adequate hair damage For dark skin type with dark, coarse hair Can treat pseudofolliculitis barbae

    30. Q-switch Nd:YAG Useful in dark skin type Induce delay hair growth Ineffective for permanent hair removal

    31. Carbon suspension Q-switch Nd:YAG Use exogenous melanin For blonde, gray or white hair Induce delay hair growth Non permanent hair removal

    32. IPL Non laser induced selective photothermolysis Wide choice of wavelength, pulse duration and delay interval Effective for all skin type Required more treatment session

    33. IPL (cont.) High risk of dyspigmentation in darker skin

    34. PDT Photosensitizer localized in follicular epithelium 40% hair reduction after 6 month of single treatment Side effect : temporary hyperpigmentation No significant hair loss but prevent regrowing hair

    35. Electro-optical synergy (ELOS) 590-1200 nm Synergy between RF (electrical) and laser or light (optical) RF : electrical heat (non selective heat) : heat focus on hair follicle and bulge area

    36. ELOS (cont.) Optical : heat from light absorbing chromophore : heat focus on hair shaft For all skin type

    37. Complication Pigmentary change : hypopigmentation : hyperpigmentation Folliculitis Blistering or crusting Scarring

    38. Complication (cont.) Koebner phenomenon in psoriasis vulgaris, vitiligo, lichen planus, Darier disease Intense pruritus Urticaria Temporary or permanent leukotrichia

    39. Complication (cont.) Found conversion of fine vellus hair to dark, coarse terminal hair or induction of growth of long fine hair from repetitive low fluence

    40. New treatment Photopneumatic therapy = broad band light with pneumatic energy Elevation of hair follicle closer to skin surface by air pressure More light absorbed by melanin in hair follicle

    41. New treatment (cont.) Minimize thermal damage to surrounding epidermal and dermal structure Reduce necessity of higher fluence No pain 5x more efficiency to delivery energy to unwanted hair

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