Continuing Medical EducationLasers in dermatology: Four decades of progress☆,☆☆,★,★★
Section snippets
Laser history
The term laser is an acronym for light amplification by the stimulated emission of radiation. Although the first laser was developed by Maiman1 in 1959 using a ruby crystal to produce red light with a 694-nm wavelength, the concept of stimulated light emission was initially introduced by Einstein2 in 1917. Einstein2 proposed that a photon of electromagnetic energy could stimulate the emission of another identical photon from atoms or molecules that are in an excited state. In 1963, Dr Leon
Laser principles
The therapeutic action of laser energy is based on the unique properties of laser light itself and complex laser-tissue interactions.13, 14, 15, 16 Laser light is monochromatic-the emitted light is of a single, discrete wavelength determined by the lasing medium (eg, solid, liquid, gas) in the optical cavity of the laser through which the light passes. At certain wavelengths of light, specific absorption of laser energy can be achieved by distinct cutaneous targets or chromophores such as
Vascular-specific lasers
Vascular-specific laser systems target intravascular oxyhemoglobin to effect destruction of various congenital and acquired vascular lesions. The 3 primary absorption peaks for oxyhemoglobin are within the visible range of the electromagnetic spectrum: 418, 542, and 577 nm. Lasers that have been used to treat vascular lesions include the argon (488-514 nm), APTD (577 and 585 nm), KTP (532 nm), krypton (568 nm), copper vapor/bromide (578 nm), PDL (585-595 nm), and Nd:YAG (532 and 1064 nm).
The
Laser treatment for hypertrophic scars, keloids, and striae
Hypertrophic scars and keloids develop as an abnormal response to cutaneous injury and are characterized by an overabundance of collagen. By definition, keloids project beyond the boundaries of the original injury and do not regress with time, whereas hypertrophic scars are raised, firm scars limited to the confines of the original injury and have a tendency toward spontaneous regression.130 These types of scars are notoriously difficult to eradicate and have a high rate of recurrence after
Pigment-specific lasers
Melanin-specific, high-energy, QS laser systems can successfully lighten or eradicate a variety of benign epidermal and dermal pigmented lesions and tattoos with minimal risk of untoward effects. Epidermal lesions (solar lentigines, ephelides, café-au-lait macules, and seborrheic keratoses); dermal and mixed epidermal/dermal lesions (melanocytic nevi, blue nevi, nevi of Ota/Ito, infraorbital hyperpigmentation, drug-induced hyperpigmentation, Becker's nevi, and nevus spilus); and amateur,
Photoepilation
Excessive hair growth in cosmetically undesirable locations may be the result of a variety of factors, ranging from hereditable causes and endocrine disease to exogenous drug therapy. Temporary hair removal methods such a shaving, tweezing, waxing, and chemical depilatories may cause irritation and are only partially effective.256, 257 Until recently, electrolysis was the only method for long-lasting hair removal; however, it is associated with as much as 50% hair regrowth and the potential for
Ablative laser systems
Cutaneous laser resurfacing has experienced unparalleled growth in the field of aesthetic operation during the past decade. High-energy, pulsed, and scanned CO2 and erbium:YAG lasers have been in widespread use since the mid-1990s and the success of these lasers in ameliorating severely photodamaged facial skin, photoinduced facial rhytides, dyschromias, and atrophic scars has been well documented.302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321
Nonablative laser systems
One of the newest trends in dermatology has been the development of nonablative laser systems for rhytides and scars with minimal morbidity or recovery time. Most of the nonablative laser systems used today emit light within the infrared portion of the electromagnetic spectrum (1000-1500 nm). At these wavelengths, absorption by superficial water-containing tissue is relatively weak, thereby effecting deeper tissue penetration. Nonablative laser resurfacing induces collagen remodeling by
Laser phototherapy
UV phototherapy has long been a mainstay in the treatment of psoriasis. In 1981, Parrish and Jaenicke442 demonstrated that the most efficient therapeutic wavelengths for the treatment of psoriasis were within the UVB spectrum. During the past decade, 311-nm narrow-band UVB has become popularized for the treatment of psoriasis, with results comparable with psoralen-UVA; however, both modalities require phototherapy sessions several times a week to achieve a therapeutic response.443 Recently, a
Optical imaging
Diagnostic, noninvasive imaging is one of the most exciting developments in laser technology. Confocal scanning laser microscopy allows real-time imaging of tissue in vivo and can provide rapid, high-resolution imaging of skin cytology including the epidermis, microvascular blood flow, and inflammatory cells.464, 465, 466, 467, 468 Using a tightly focused, low-power, near-infrared light source, the confocal microscope illuminates a small spot in the specimen that is subsequently imaged onto a
Laser safety
Laser safety has become a more complex issue as more cutaneous laser systems have become available for treatment. Of paramount importance is the general safety of both the patient and the operating room personnel during laser irradiation. Although most lasers are now used in private offices and smaller surgical suites, adherence to strict safety guidelines is essential to prevent intraoperative injury or serious complications during the postoperative period.
Key laser safety issues include
Anesthesia
Most dermatologic laser procedures can be performed without any form of anesthesia. PDLs and LP lasers typically produce minimal discomfort (analogous to a rubber band snapping on the skin). When concomitant epidermal cooling is applied, only a slight stinging sensation is experienced. Thus, PDL or LP laser irradiation can usually be tolerated by patients without anesthesia, particularly when small areas are being treated. The QS lasers are also used without anesthesia for small treatment
Side effects and complications
Because of the varied side effects and complications possible after cutaneous laser therapy, it is essential that each patient receive consultation and counseling before treatment to assess his or her specific risk of adverse sequelae. It is also important that patients understand the importance of good wound care after a laser procedure. Preoperative laser evaluation should include a basic medical history including documentation of medications and allergies. A history of abnormal scarring,
Conclusion
Although lasers capable of cutaneous application have been available for more than 4 decades, it has been only within the past several years that their use gained widespread acceptance within the medical field. Lasers have essentially revolutionized cosmetic dermatology, providing safe and reliable means for treating a variety of cutaneous pathologies. It is now possible to treat such varied skin conditions as benign vascular and pigmented birthmarks, tattoos, hypertrophic scars and keloids,
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Cited by (0)
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Funding sources: None.
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Conflict of interest: None identified.
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Reprint requests: Tina S. Alster, MD, Washington Institute of Dermatologic Laser Surgery, 2311 M St NW, Suite 200, Washington, DC 20037. E-mail: [email protected].
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