Principles of laser and intense pulsed light for cutaneous lesions
- George J Hruza, MD
George J Hruza, MD
- Adjunct Professor of Dermatology and Otolaryngology
- St. Louis University School of Medicine
When absorbed in sufficient amounts, light energy can induce changes in the skin. Lasers and intense pulsed light (IPL) devices allow for the delivery of light to the skin in a controlled manner. These devices are useful for achieving desired clinical effects in a variety of dermatologic conditions.
The term laser is an acronym for light amplification by stimulated emission of radiation. Lasers deliver monochromatic, coherent, collimated, high intensity beams of light. In contrast, IPL devices are filtered flashlamps that emit polychromatic, noncoherent light in a broad range of wavelengths. Thus, IPL devices are dimmer and less powerful than lasers.
For many years following the initial studies of the effects of lasers on the skin [1-4], the use of lasers was limited to nonselective coagulation and vaporization of tissue . A revolution in the clinical utility of lasers occurred in the early 1980s with the development of the theory of selective photothermolysis . This theory describes the parameters by which light can be used to selectively destroy targets in the skin through the selective absorption of light and spatial confinement of the effect. The majority of subsequent developments in laser technology for cutaneous disorders have been based upon this theory.
Progress in laser and IPL technology has also involved the development of safer and more efficient methods of achieving the desired effects on skin. Cooling technology limits inadvertent damage to tissues adjacent to targeted sites, allowing higher levels of light energy to be directed towards the target. In addition, the implementation of fractionated laser technology for cutaneous resurfacing has allowed for the achievement of the desired cosmetic outcome with reduced healing time.
The principles that govern the interactions between skin and laser light or IPL, and the types of these devices used in the treatment of skin will be discussed here. Background information on the production and basic characteristics of laser light, the treatment of cutaneous vascular and hyperpigmented lesions with laser light, and ablative laser resurfacing for skin rejuvenation are reviewed separately. (See "Basic principles of medical lasers" and "Laser and light therapy for cutaneous vascular lesions" and "Laser and light therapy for cutaneous hyperpigmentation" and "Ablative laser resurfacing for skin rejuvenation".)
- GOLDMAN L, BLANEY DJ, KINDEL DJ Jr, FRANKE EK. Effect of the laser beam on the skin. Preliminary report. J Invest Dermatol 1963; 40:121.
- GOLDMAN L, BLANEY DJ, KINDEL DJ Jr, et al. Pathology of the effect of the laser beam on the skin. Nature 1963; 197:912.
- GOLDMAN L, WILSON RG, HORNBY P, MEYER RG. RADIATION FROM A Q-SWITCHED RUBY LASER. EFFECT OF REPEATED IMPACTS OF POWER OUTPUT OF 10 MEGAWATTS ON A TATTOO OF MAN. J Invest Dermatol 1965; 44:69.
- Maiman T. Stimulated optical radiation in ruby. Nature 1960; 187:493.
- Apfelberg DB, Maser MR, Lash H. Extended clinical use of the argon laser for cutaneous lesions. Arch Dermatol 1979; 115:719.
- Anderson RR, Parrish JA. Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation. Science 1983; 220:524.
- Tan OT, Murray S, Kurban AK. Action spectrum of vascular specific injury using pulsed irradiation. J Invest Dermatol 1989; 92:868.
- Dierickx CC, Casparian JM, Venugopalan V, et al. Thermal relaxation of port-wine stain vessels probed in vivo: the need for 1-10-millisecond laser pulse treatment. J Invest Dermatol 1995; 105:709.
- Dover JS, Margolis RJ, Polla LL, et al. Pigmented guinea pig skin irradiated with Q-switched ruby laser pulses. Morphologic and histologic findings. Arch Dermatol 1989; 125:43.
- Babilas P, Shafirstein G, Bäumler W, et al. Selective photothermolysis of blood vessels following flashlamp-pumped pulsed dye laser irradiation: in vivo results and mathematical modelling are in agreement. J Invest Dermatol 2005; 125:343.
- Arndt KA. Argon laser therapy of small cutaneous vascular lesions. Arch Dermatol 1982; 118:220.
- Craig RD, Purser JM, Lessells AM, Hufton AP. Argon laser therapy for cutaneous lesions. Br J Plast Surg 1985; 38:148.
- Lowe NJ, Lask G, Griffin ME, et al. Skin resurfacing with the Ultrapulse carbon dioxide laser. Observations on 100 patients. Dermatol Surg 1995; 21:1025.
- Teikemeier G, Goldberg DJ. Skin resurfacing with the erbium:YAG laser. Dermatol Surg 1997; 23:685.
- Lu SY, Lee CC, Wu YY. Hair removal by long-pulse alexandrite laser in oriental patients. Ann Plast Surg 2001; 47:404.
- Nelson JS, Berns MW. Basic laser physics and tissue interactions. Contemporary Dermatology 1988; 2:1.
- Manstein D, Herron GS, Sink RK, et al. Fractional photothermolysis: a new concept for cutaneous remodeling using microscopic patterns of thermal injury. Lasers Surg Med 2004; 34:426.
- Svaasand LO, Nelson JS. On the physics of laser-induced selective photothermolysis of hair follicles: Influence of wavelength, pulse duration, and epidermal cooling. J Biomed Opt 2004; 9:353.
- Chang CJ, Nelson JS. Cryogen spray cooling and higher fluence pulsed dye laser treatment improve port-wine stain clearance while minimizing epidermal damage. Dermatol Surg 1999; 25:767.
- Lask G, Keller G, Lowe N, Gormley D. Laser skin resurfacing with the SilkTouch flashscanner for facial rhytides. Dermatol Surg 1995; 21:1021.
- Khoury JG, Saluja R, Goldman MP. Comparative evaluation of long-pulse alexandrite and long-pulse Nd:YAG laser systems used individually and in combination for axillary hair removal. Dermatol Surg 2008; 34:665.
- Bäumler W, Eibler ET, Hohenleutner U, et al. Q-switch laser and tattoo pigments: first results of the chemical and photophysical analysis of 41 compounds. Lasers Surg Med 2000; 26:13.
- Brauer JA, Reddy KK, Anolik R, et al. Successful and rapid treatment of blue and green tattoo pigment with a novel picosecond laser. Arch Dermatol 2012; 148:820.
- Fincher EF, Gladstone HB. Use of a dual-mode erbium:YAG laser for the surgical correction of rhinophyma. Arch Facial Plast Surg 2004; 6:267.
- Orenstein A, Goldan O, Weissman O, et al. A new modality in the treatment of actinic cheilitis using the Er:YAG laser. J Cosmet Laser Ther 2007; 9:23.
- Kono T, Chan HH, Groff WF, et al. Prospective direct comparison study of fractional resurfacing using different fluences and densities for skin rejuvenation in Asians. Lasers Surg Med 2007; 39:311.
- Sherling M, Friedman PM, Adrian R, et al. Consensus recommendations on the use of an erbium-doped 1,550-nm fractionated laser and its applications in dermatologic laser surgery. Dermatol Surg 2010; 36:461.
- Hunzeker CM, Weiss ET, Geronemus RG. Fractionated CO2 laser resurfacing: our experience with more than 2000 treatments. Aesthet Surg J 2009; 29:317.
- Mahmoud BH, Srivastava D, Janiga JJ, et al. Safety and efficacy of erbium-doped yttrium aluminum garnet fractionated laser for treatment of acne scars in type IV to VI skin. Dermatol Surg 2010; 36:602.
- Sadick NS, Weiss R, Kilmer S, Bitter P. Photorejuvenation with intense pulsed light: results of a multi-center study. J Drugs Dermatol 2004; 3:41.
- Asawanonda P, Anderson RR, Chang Y, Taylor CR. 308-nm excimer laser for the treatment of psoriasis: a dose-response study. Arch Dermatol 2000; 136:619.
- Alster TS, Tanzi EL, Welsh EC. Photorejuvenation of facial skin with topical 20% 5-aminolevulinic acid and intense pulsed light treatment: a split-face comparison study. J Drugs Dermatol 2005; 4:35.
- Kawada A, Aragane Y, Kameyama H, et al. Acne phototherapy with a high-intensity, enhanced, narrow-band, blue light source: an open study and in vitro investigation. J Dermatol Sci 2002; 30:129.
- SKIN OPTICS
- SELECTIVE PHOTOTHERMOLYSIS
- THERAPEUTIC PARAMETERS
- Pulse duration
- - Thermal relaxation time
- - Large versus small structures
- Spot size
- FRACTIONAL PHOTOTHERMOLYSIS
- SKIN COOLING
- CLASSIFICATION OF DEVICES
- Continuous and quasi-continuous wave lasers
- Pulsed lasers
- Fractionated lasers
- - Nonablative
- - Ablative
- Intense pulsed light
- OTHER LASER/LIGHT TISSUE INTERACTIONS
- Excimer laser
- Photodynamic therapy
- SUMMARY AND RECOMMENDATIONS