SKIN AND SOFT TISSUE
CHAPTER 18 LASERS IN PLASTIC SURGERY
DAVID W. LOW AND IVONA PERCEC
Plastic surgeons recognized the potential benefit of treating vascular lesions with lasers in the 1980s, but it was not until the widespread popularity of laser skin resurfacing in the following decade that most plastic surgeons jumped on laser surgery bandwagon. Taking advantage of the public’s fascination with high-technology, laser therapy has been partially misrepresented as the “state-of-the-art” treatment for a variety of conditions. Often described as painless, and exaggerated as producing perfect results, lasers have been misused as a marketing tool to lure patients away from conventional, low-tech techniques that can often produce equivalent results at significantly lower cost. On the other hand, there are some conditions such as port wine stains that are best treated by laser, and the standard of care demands familiarity with this treatment modality.
The modern plastic surgeon is therefore faced with the dilemma of trying to sort out which lasers are best for which conditions, which manufacturers’ claims are credible, and, ultimately, which lasers are the safest investment in a rapidly changing world of high-tech solutions to a variety of reconstructive and cosmetic problems.
This chapter provides a basic introduction to laser technology, laser tissue interactions, and examples of what conditions are appropriate for laser treatment with currently available laser technology. Laser safety is an important consideration for both the patient and the treating physician, and safety issues are discussed at the end of the chapter.
How Laser Light Is Produced
Criminal masterminds Auric Goldfinger and Dr. Evil were fascinated by amplified light, “a sophisticated heat beam which we called a ‘laser,’” but fortunately in the 21st century, most lasers are used instead for therapeutic purposes. Although the vast array of available lasers can be confusing, laser physics are straightforward, and only a basic understanding of light energy is necessary to understand how lasers work. Light energy can be described as either a series of particles (photons) or as a wave phenomenon. The color of light is determined by the distance between two successive waves (the wavelength, usually measured in nanometers). The human eye can see only a narrow range of the electromagnetic spectrum (visible light), and many lasers produce invisible light in the infrared range.
A molecule or atom in its resting state is composed of a nucleus and circulating electrons. If energy is added to the system, the electrons become excited and circulate at a higher orbit. Eventually, an excited electron will fall back to its resting orbit, releasing a specific packet of energy—a photon. That photon has a wavelength specific to that molecule. Some molecules have more than one excited orbit, and therefore, the light emitted may have more than one wavelength. If a photon collides with an excited electron, that electron falls back to its resting orbit, thereby releasing another photon. The two photons are in phase, meaning their wave patterns are synchronized and therefore reinforce each other. As these photons hit other excited electrons, more photons are released and the light energy increases (Figure 18.1).
A laser tube has a mirror at each end and contains a solid, liquid, or gas medium within it whose electrons are in a resting state. As energy is added to the system, the majority of the electrons become excited (population inversion) and begin to release photons. Only those photons that hit the mirrors directly are reflected back into the lasing medium, creating more and more photons that travel back and forth between the mirrors, parallel to the tube. Since the photons are in phase, the intensity of the light increases in the tube. This phenomenon has been described as light amplification by the stimulated emission of radiation, or the more familiar term LASER. (In contrast, TASER is an acronym for Thomas A. Swift’s Electric Rifle and has nothing to do with light energy.) To allow light to escape from the tube, one of the mirrors is only partially reflecting. The emitted light is coherent; it is in phase, parallel, and in most cases monochromatic. In contrast, incandescent light is noncoherent, meaning it has many wavelengths and is not parallel.
Light energy can be visible or invisible depending upon its wavelength. The spectrum of electromagnetic radiation ranges from long radio waves (wavelength > 10 cm) to extremely short gamma rays (<10–11 m). The entire spectrum includes radio, microwaves, infrared, visible (400 to 700 nm), ultraviolet, X-ray, and gamma rays.
Types of Lasers
The laser tube may contain either a gas, liquid, or solid lasing medium (Table 18.1), and new lasers are constantly being invented and promoted to the medical community. The first laser, invented in 1960, used a synthetic ruby rod, and other solid crystal lasers include yttrium aluminum garnet (YAG). The YAG crystal contains neodymium, erbium, or holmium ions, each with its own specific wavelength and tissue interactions. In a dye laser, the medium is a solution of a fluorescent dye in a solvent such as methanol. Organic rhodamine dye is used in the yellow dye laser, and although the earlier dye lasers had adjustable (tunable) wavelengths ranging from yellow to red, currently available dye lasers offer single wavelength light energy. In a helium–neon laser, it is a mixture of the gases helium and neon. In a diode laser, it is a thin layer of semiconductor material sandwiched between other semiconductor layers. Excimer lasers (the name is derived from the terms excited and dimers) use reactive gases, such as chlorine and fluorine, mixed with inert gases such as argon, krypton, and xenon. When electrically stimulated, a pseudomolecule (dimer) produces light in the ultraviolet range.
FIGURE 18.1. Laser physics. A photon is released when an excited electron fall returns to its resting orbit. If the photon strikes another excited electron, a second photon is released. The stimulated emission of multiple photons produces light of increasing intensity.
Laser Tissue Interactions
When the laser strikes an object, a variety of desirable and undesirable effects may result as the light is reflected, scattered, transmitted, or absorbed. A series of reflecting mirrors directs CO2 laser light to the handpiece, but reflected CO2 light off of a shiny surgical instrument is hazardous. The risk of inadvertent light reflection can be reduced by using ebonized instruments. The dull finish scatters laser light, diffusing the concentrated energy beam. Glass and clear liquids will transmit some types of laser light, allowing photocoagulation through glass slides, the vitreous of the eye, and water. Some lasers will also pass through the epidermis, allowing the energy to reach dermal vessels and pigment without disrupting the epidermal layer. It is the absorbed light that causes desirable or undesirable biologic effects. Except for the excimer lasers that break chemical bonds, most laser energy is converted into thermal (heat) energy. Depending upon the rate of tissue heating, surgical effects includewelding, coagulation, protein denaturation, dessication, and vaporization. Some lasers will indiscriminantly target living tissue, while other lasers will semiselectively target a specific chromophore such as oxyhemoglobin, melanin, and tattoo pigmentation. Selective photothermolysis describes the ability of lasers to target blood vessels or pigment without harming the surrounding epidermis or dermis. It is generally safer to deliver cutaneous laser light in pulses rather than as a continuous beam, as the interval between pulses allows the tissue to cool before the heat is transferred to the surrounding dermis. Pulsed lasers respect the thermal relaxation time of dermal vessels (the time to dissipate the heat absorbed during a laser pulse).
Ablative Lasers. Lasers that nonspecifically destroy the tissue can be used to remove skin lesions or remove layers of skin, usually with minimal blood loss because the dermal vessels are coagulated as the tissue is vaporized. CO2 laser light is absorbed by intracellular water, which vaporizes the tissue as the water turns to steam.
Vascular Lesion Lasers. The fact that oxyhemoglobin absorbs green and yellow light has spawned a variety of lasers appropriate for treating dermal vessels. Historically, the argon (blue/green) laser was the first clinically useful laser, but yellow light has become the preferred color (oxyhemoglobin absorption peak at 577 nm yellow light), with the pulsed yellow dye laser (intentionally adjusted to 585 and 595 nm for greater dermal penetration) as the most popular type. The high-energy/short-duration pulse causes vascular disruption as the blood rapidly heats up and expands. The potassium titanyl phosphate (KTP) laser (532 nm—green light) also targets oxyhemoglobin, but the pulses are much longer in duration and tend to coagulate rather than disrupt vessels. The diode laser (800 nm) can also be used for vascular lesions, as the light is absorbed by both oxyhemoglobin and melanin.
Pigmented Lesion Lasers. Pigmented lesion lasers target melanin. Benign pigmented lesions such as lentigines, café au lait spots, melasma, and Nevus of Ota or Ito may improve with a series of laser treatments. Although congenital nevi will also lighten with laser therapy, this remains controversial; although it is unlikely that laser will increase the risk of malignant transformation, it may delay the diagnosis of a changing nevus by masking the color change associated with a melanoma.
Photodynamic Therapy. The use of light-activated drugs to treat acne and other skin conditions currently is best represented by Levulan (topical 5-aminolevulinic acid, DUSA pharmaceuticals). The compound is metabolized by sebaceous glands into porphyrins. The acne bacteria itself also produces porphyrin, and the use of blue, green, or red light stimulates the production of oxygen free radicals that destroy the bacteria and suppress the sebaceous gland activity. Photodynamic therapy has also been used for actinic keratoses, non-melanotic skin cancer, T-cell lymphoma, and photorejuvenation.1
Nonlaser Phototherapy. Intense pulsed light (IPL) is not actually laser light. Xenon flashlamps generate multiwavelength noncoherent light that is partially modulated by a series of filters. IPL is used for sun-related pigmentary changes, telangiectasias, and hair removal. In radiofrequency treatment, radio waves are used to heat the collagen of the dermis and subdermis. It is thought to cause collagen contraction and stimulation of new collagen production. It has been promoted as a noninvasive, nonablative treatment for skin laxity in many areas of the body, including the face. Although some publicized results are impressive, the ability to consistently achieve such results is far less predictable than surgical skin tightening. Proper patient selection remains a clinical challenge.
SPECIFIC LASER TREATMENTS (TABLE 18.2)
Hemangiomas. Hemangiomas are the most common benign tumor of infancy, and at least 60% occur in the head and neck region. Although an estimated 70% of hemangiomas regress satisfactorily, 30% of patients still have cosmetically significant deformities. Parents are eager to seek treatment options on a proactive basis, and the laser is a potentially useful option in several settings.2 The pulsed yellow dye laser may be useful for very early hemangiomas, ulcerated hemangiomas, and regressed hemangiomas that still contain vascular pigmentation or visible ectatic vessels. The laser only penetrates about a millimeter into the skin, and therefore, it is most effective for small flat hemangiomas. Parents should be advised that multiple laser treatments may be necessary every 2 to 4 weeks during the proliferative phase, as hemangiomas will often exhibit temporary regression followed by rebound growth. Laser therapy can be discontinued when the hemangioma finally enters a permanent state of regression. Topical application of anesthetic cream may be desirable to reduce both the patient and the parent discomfort. Laser treatments are not effective for already bulky or subcutaneous hemangiomas, as the light will not penetrate deeply enough to produce a noticeable improvement.
FIGURE 18.2. A and B. Ulcerated perineal hemangioma. Pulsed dye laser may significantly reduce the pain and facilitate healing of the wound, possibly by coagulation of the nerves and suppression of the proliferating vessels.
Ulcerated hemangiomas can be excruciatingly painful, especially when located in the perineal region. There has been some success with pulsed yellow dye laser treatment of these hemangiomas, with some babies showing significant pain relief within 24 to 48 hours, probably due to coagulation of the sensitive nerve endings within the wound. Faster healing has also been reported, although the mechanism for this observation is unclear. Perhaps, the laser induces some regression of the hemangioma, or wound care is facilitated once the area becomes less sensitive, allowing for more rapid re-epithelialization (Figure 18.2A, B).
Lastly, hemangiomas that have regressed well enough to avoid the need for surgical excision may have residual ectatic vessels that will improve with pulsed dye laser therapy. Larger telangiectasias may also respond to simultaneous sclerotherapy and laser treatment. Endothelial injury from the sclerosant followed by laser photocoagulation of the vessels may have a synergistic benefit in removing these residual vessels.
Capillary Vascular Malformations. Port wine stains tend to darken with age as the dilated dermal capillaries and venules enlarge with time. The involved area may also show textural changes and soft tissue hypertrophy, and hyperplastic vascular nodules (pyogenic granulomas) may develop, with problematic bleeding. The pulsed dye laser (595 nm) is the treatment of choice.2-4 Children respond better than teenagers and adults, possibly because the immature vessels are more photosensitive, and treatment can be offered beginning in infancy (Figure 18.3). Parents should be advised that multiple (at least six to eight) treatments are recommended for cumulative benefit, and that it is extremely rare for any capillary vascular malformation to completely disappear. Associated bruising from the laser lasts for about 2 weeks, and gradual lightening of the vascular pigmentation may continue for at least 2 months. Patients can be treated every 2 to 3 months. Although topical anesthetic cream can be very useful on the trunk and extremities and for small areas of the face, most children with large facial port wine stains will be better treated under a general anesthetic. Metal eye shields are available for periorbital laser therapy, and placement of the shield directly on the globe permits laser treatment of the eyelid skin. The eyelashes can be shielded by strategic placement of the wrapper of an alcohol wipe, to avoid undesirable singeing of the hairs. Eyebrows will also singe if lased, but the light does not penetrate deeply enough to cause permanent suppression of hair growth.
Venous Malformations. Venous malformations consist of dilated clusters of varicose veins, and treatment options include laser photocoagulation, sclerotherapy, and surgical debulking. Small superficial veins may improve with pulsed dye laser therapy, but usually the energy pulse is too brief and the vessels are too large to show significant benefit. Longer energy delivery with a continuous wave laser such as the KTP or neodymium:YAG laser can result in significant heat absorption and vascular destruction, with a significant shrinkage in the size of the malformation.5,6 In this setting, although the target chromophore is still oxyhemoglobin, the prolonged energy delivery probably achieves its effect by nonspecific heat delivery to all tissues in the area, and the risk of post-laser scarring is higher. For this reason, the lips and oral mucosa are more forgiving areas when one uses continuous laser energy. For other areas of the body, or if the physician wants to avoid excessive energy delivery to the surface layer, the fiberoptic tip can be passed intralesionally for deep coagulation. With the KTP laser, the glass tip can be placed directly on the mucosa, and a brief pulse will create a small hole through which the laser can be passed transmucosally to the heart of the malformation. In other areas, a large gauge hypodermic needle can be used to penetrate and protect the skin while passing the laser fiber. The physician must understand that this technique is highly operator dependent and somewhat blind. A high level of concentration is necessary with constant verification of the location of the tip of the fiber by palpation or transillumination of the light, to decrease the risk of thermal injury to the dermis or perforation of the overlying intact skin.
FIGURE 18.3. Port wine stain. The pulsed yellow dye laser remains the laser of choice for pediatric capillary vascular malformations (port wine stains). Multiple treatments are necessary to progressively lighten the vascular pigmentation, and the laser is unlikely to completely remove the stain.
Large venous malformations can be debulked by standard surgical techniques or by using the fiber of a KTP or neodymium:YAG laser as a contact tip laser scalpel.
Endovenous laser photocoagulation with the assistance of ultrasonic guidance is now a therapeutic option for cosmetic varicose veins as well as congenital venous malformations, usually performed by interventional radiologists and vascular surgeons.7
Lymphatic Malformations. Cutaneous vesicles resembling tiny water blisters represent the dermal component of a lymphatic malformation, which is usually associated with a more extensive subcutaneous component. Problematic lymphatic oozing from ulcerated vesicles can be palliatively treated with the CO2 laser, which is absorbed by water. The heat of the absorbed laser energy may cause a desirable fibrosis of the dermis at the site of leaking lymphatic cisterns, in a sense “capping the well.” The treatment is palliative rather than curative, but can be easily repeated for unresectable lesions.
Venolymphatic Malformations. Similar to lymphatic malformations, but associated with an additional venous component, the cutaneous component may present as tiny purple vesicles or crusting scabs (angiokeratomas). This is commonly seen in Klippel–Trenaunay syndrome (patchy capillary malformation with an underlying venolymphatic malformation and hypertrophy of the involved extremity). The vesicles tend to be more responsive to coagulation by a continuous laser rather than a pulsed laser; therefore, the KTP laser is more effective than the pulsed yellow dye laser. Crusting lesions can be tangentially shaved, then compressed with a glass slide to control bleeding while being lased. Long-standing large crusted lesions may be more efficiently excised and oversewn. Since the cutaneous lesions overlie a much more extensive subcutaneous component, treatment is purely palliative, and reoccurrence is to be expected.
Telangiectasias/Rosacea. Commonly called “broken blood vessels” by the lay public, telangiectasias represent undulating dilated dermal vessels that course through the dermal layer. They appear discontinuous because they are visible near the surface, and then disappear as they dive into the deeper dermis. Associated with accumulated UV damage or rosacea, they respond to a variety of vascular lesion lasers. Smaller telangiectasias also respond to IPL therapy. Multiple treatment sessions are necessary for optimal results, and adult patients should be aware of the significant prolonged bruising (2 to 3 weeks) that can be associated with certain lasers and laser settings.
Pyogenic Granulomas. Pyogenic granulomas are shiny nodules of proliferative vascular tissue covered by a fragile epidermal layer (lobular capillary hemangioma) that have an annoying propensity to bleed when ulcerated. Commonly occurring in children and in pregnant women, they can occur at any age and may be the result of minor trauma. Although surgical excision is curative, tangential shave excision followed by laser photocoagulation of the dermal base will often leave an imperceptible scar. A glass slide can be used to compress the bleeding base, and a continuous laser such as the KTP laser will pass through the glass and coagulate the residual proliferative lesion (Figure 18.4A, B). Although the pulsed dye laser alone has been reported as a treatment option, multiple laser sessions may be necessary for large lesions, and no specimen is available for pathologic confirmation.
Spider Angiomas These superficial vascular lesions are characterized by a central feeding arteriole and radiating branches. Compression of the skin will blanch the lesion, which will then readily reappear at the center and expand outward after the pressure is released. Although small angiomas can be successfully treated by destroying the central feeding vessel by electric cautery, long-standing angiomas often will have a persistent peripheral blush. The pulsed yellow dye laser is an excellent way to coagulate the entire lesion. The central feeding vessel may require a series of stacked pulses to destroy it, and it should appear black at the end of the treatment session. Patients should be aware that reoccurrence may require more than one treatment.
Cherry Angiomas. Also known as senile angiomas, these superficial macular or papular cherry-colored nodules are commonly seen on adult skin. They may range in size from punctuate lesions to several millimeters. Any of the vascular lesion lasers can be used to destroy them.
Spider Veins/Vricose Veins. Dilated leg spider veins may respond to a variety of lasers, but it is usually most efficient to remove the larger varicose veins first. Traditionally, a varicose greater saphenous vein is best treated by stripping and ligation, while other varicose veins and large spider veins will respond to sclerotherapy. Endovenous laser therapy using a 810 nm diode laser with a bare fiber has become a viable treatment alternative.7
FIGURE 18.4. A and B. Pyogenic granuloma. A biopsy is taken prior to laser photocoagulation of the residual dermal proliferating vessels. The KTP laser light will pass through the glass slide, which is used to compress the bleeding vessels. Note the protective laser eyeshield.
Pulsed dye laser (595 nm) or diode laser (800 nm) light will penetrate into the deep dermis to treat residual spider veins as well as the peripheral blush that is often seen after sclerosis of the larger vessels. Laser treatment requires photocoagulation along the entire course of the vessel for best results, which is why patients with extensive spider veins may be more efficiently treated initially by sclerotherapy.
Adenoma Sebaceum/Tuberous Sclerosis. Patients with tuberous sclerosis will develop firm pink nodules in a butterfly pattern across their cheeks and nose, with additional involvement of their chins and foreheads. Neither adenomatous nor sebaceous, these lesions are more accurately angiofibromas. Although theoretically photocoagulation with a vascular lesion laser should improve these dermal lesions, vaporization with a defocused CO2 laser appears to be much more efficient and effective in improving the skin surface contour. The heat of the laser coagulates the exposed dermis, making the procedure virtually bloodless, in contrast to dermabrasion or shave excision. Retreatment for recurrent nodules is common and easily repeated (Figure 18.5A, B).
Pigmented Lesions. Melanin absorbs light in the ultraviolet to near infrared range; therefore, a wide variety of lasers have been used to target benign melanocytic lesions. Blue, green, red, and infrared wavelengths have been used. Although historically continuous wave lasers such as argon were initially useful, pulsed lasers are safer and less likely to cause scarring. Shorter wavelengths will treat epidermal pigmentation, while longer wavelengths are more effective for dermal pigmentation.7 Epidermal lesions such as freckles (ephelides), solar lentigines, and labial melanocytic macules may respond to green pulsed dye (510 nm), KTP, also known as a frequency-doubled YAG laser (532 nm), while deeper dermal pigmented lesions such as café au lait spots, nevus of Ota (melanocytic pigmentation in the V1 and V2 distribution), and nevus of Ito (shoulder or upper arm distribution) may respond to longer wavelength ruby (694 nm), alexandrite (755 nm), and diode (800 nm) lasers.
FIGURE 18.5. A and B. Tuberous sclerosis. The CO2 laser readily vaporizes the raised angiofibromas and coagulates the dermal vessels. Treatment is purely palliative, but results tend to be better than pulsed dye laser therapy.
Neurofibromatosis. Large plexiform neurofibromas should be excised or debulked by standard surgical techniques, but patients who request removal of hundreds of small neurofibromas may be well served by CO2 laser destruction or excision. The laser in a slightly defocused mode can vaporize and coagulate small neurofibromas. Large sessile or pedunculated neurofibromas can be readily excised with minimal bleeding by vaporizing a ring of skin around the base of the lesions with a focused beam, then amputating the subcutaneous tumor with a defocused beam to achieve better coagulation. Small excision sites can be left to heal spontaneously, while larger wounds can be loosely closed with a couple of monofilament sutures. Patients should be reminded that the treatment is palliative.
Syringomas/Cylindromas. Syringomas are benign tumors of eccrine origin, most commonly found in the periorbital area. CO2 laser vaporization results in rapid obliteration of these lesions, often without recurrence. Cylindromas are nodular dermal benign tumors thought to be of primitive sweat gland origin, an autosomal dominant inheritance pattern associated with multiple cylindromas. Large disfiguring nodules involving the face and scalp (so-called turban tumor) can be excised or vaporized with the CO2 laser to reduce associated operative blood loss. The procedure is only palliative.
Actinic Keratosis. Patients with extensive actinic changes of their facial skin or lower lip are candidates for laser skin resurfacing. This may be better tolerated than topical 5-fluorouracil therapy or a surgical lower lip vermilion shave. The CO2 laser can readily vaporize the epidermis and papillary dermis, allowing the regeneration of healthier skin. The laser will also readily vaporize the vermilion of the lower lip, which heals remarkably well in 2 to 3 weeks. Although painful until the vermilion mucosa regenerates, it avoids the need for a mucosal advancement flap.
Verruca Vulgaris. Wart removal is associated with a long list of treatment modalities with variable rates of success, and most surgical strategies involve reduction of the viral burden by excision or destruction of the affected skin. The CO2 laser has been most commonly used to vaporize the involved area, particularly when there are multiple lesions that may make surgical excision difficult or undesirable. To reduce the risk of viral transmission to medical personnel, it is advisable to sharply excise the bulk of the lesion, and then vaporize the base. A viral (N95) mask for all participants (including the patient) and the use of a plume evacuator are mandatory to minimize the possibility of inoculation of the bronchial tree. For small warts, some success has also been associated with the pulsed dye laser. Presumably, energy delivery to the dermis layer either sterilizes it or makes the local environment inhospitable for the wart virus.
Sebaceous Nevi (Nevus Sebaceus of Jadassohn) and Rhinophyma. This congenital nevus is most commonly excised when it is located in the hair-bearing scalp because of the 15% risk of basal cell transformation in adulthood. Additionally, the nevus is characteristically non-hairbearing, and it may become more cosmetically annoying during puberty with stimulation of the sebaceous glands. However, sebaceous nevi on the face may leave a cosmetically disfiguring scar if excised. Superficial laser vaporization with the CO2 laser may offer surface textural improvement. More recently, the use of photodynamic therapy with Levulan (topical 5-aminolevulinic acid) and laser activation has been shown to suppress sebaceous gland activity in acne and may have applicability in suppression of sebaceous nevi. Rhinophyma, characterized by hypertrophic sebaceous glands and marked thickening and distortion of the dermis layer of the nose, can be effectively vaporized with the CO2 laser with minimal bleeding. The end result is superior to shave excision and skin grafting (Figure 18.6A, B).
FIGURE 18.6. A and B. Rhinophyma. The ultrapulse CO2 laser with a 3 mm handpiece vaporizes hypertrophic sebaceous glands and thick dermis in a hemostatic and controlled fashion to achieve significant contour improvement. Re-epithelialization takes place over several weeks.
Epidermal Nevi. Epidermal nevi, while possessing no significant malignant risk, can cause severe disfigurement as the nevi thicken and create a verrucous surface texture. Palliative options include tangential shave excision, dermabrasion, and full thickness excision, but CO2 laser vaporization may provide a fast and clean way to improve the surface texture with minimal bleeding. For relatively thin but raised epidermal nevi, the laser appears to vaporize the nevus along a clean and consistent dermal plane. Thicker nevi may require multiple laser passes, and extensively verrucous lesions seem to lack a clear cleavage plane with less satisfying surface uniformity. Wounds are covered with topical antibiotic ointment and are left to re-epithelialize. Patients must understand that this treatment is usually not curative and future treatment sessions may be desirable for recurrent skin thickening.
Lentigines. Benign pigmented lesions associated with sun exposure and freckles will respond to a wide range of wavelengths. Green light lasers (510 nm pulsed dye, 532 KTP laser), diode lasers (800 nm), and nonlaser IPL will lighten melanocytic pigmentation. These lasers will also lighten melanocytic nevi, and clinical discretion must always be exercised when deciding which lesions can be safely treated and which deserve biopsy prior to laser treatment.
Hair Removal. The basic principle of laser hair removal is to use light energy to destroy the hair root for permanent hair reduction.8 This requires a deeply penetrating wavelength that must reach the dermal papilla without adversely destroying the surrounding dermis. Most hair removal lasers target melanin, and deeply penetrating lasers such as the diode (800 nm), alexandrite (755 nm), and YAG (1,064 nm) lasers are most effective on patients with dark hair and fair skin. Patients with light or grey hair are poor candidates for these lasers, even with efforts to darken the hairs with carbon particles. IPL with its range of wavelengths (510 to 1,200 nm) has been promoted as a useful method of hair reduction for patients with fair hair.
Patients should be advised that multiple treatment sessions are the routine and that hair removal is not necessarily permanent. Hair reduction and delayed hair regrowth are more realistic goals than complete hair removal.
Tattoo Removal. Tattoos are created by pigment or foreign matter that is imbedded in the dermis layer of the skin, intentionally in the case of decorative tattoos, therapeutically in the case of radiation marking or nipple/areola reconstruction, and traumatically in the case of road rash. Historically, the tattoos have been removed by abrasion of the skin, until the deepest pigment has been removed. This routinely leaves shiny, atrophic scars at best, and hypertrophic or keloid scars in unfavorable areas. The CO2 laser is simply a high-tech method of dermabrasion and offers little advantage over mechanical dermabrasion. The advent of Q-switched ruby, YAG, and Alexandrite lasers offers the possibility of tattoo removal without clinically apparent scarring.9,10 Pigment granules are fragmented into smaller particles that are then phagocytized by macrophages.
Black ink is the most common color in tattoos, followed by blue, green, red, yellow, and orange. Additional colors such as pink, brown, purple, and fluorescent colors make tattoo removal by a single laser more difficult, as a particular color may reflect rather than absorb the laser light. For example, red tattoos will reflect ruby laser light (694 nm) but will absorb wavelengths below 575 nm. The Q-switched YAG laser (1,064 nm) has a frequency-doubling KTP crystal, which emits green light at 532 nm, thereby making it effective for red tattoos.
Black and blue ink is well absorbed at all wavelengths and is effectively treated by the ruby, the YAG, and the Alexandrite laser. The Alexandrite laser is also good for green pigment. The 510 nm flashlamp-pulsed dye laser was originally developed to treat melanocytic lesions, but the short pulse width (300 ns) has the capability to fragment pigment granules and is effective for red, purple, orange, and yellow pigments.
Patients should be advised that multiple treatment sessions are necessary, scarring may occur, colors may not lighten sufficiently, and some colors that contain iron oxide pigments (such as flesh tones) may paradoxically darken to black as a result of the extreme temperatures generated by the Q-switched lasers. Additionally, gunpowder tattoos may ignite when subjected to the extremely high temperatures of the Q-switched lasers, resulting in thermal burns.
Recently, topical application of imiquimod cream, FDA (Food and Drug Administration) approved in 1997 to treat premalignant and malignant skin cancers such as actinic keratosis, Bowen’s disease, and basal cell skin cancer, as well as genital warts, has been shown to lighten tattoos. A combination of imiquimod and laser treatments has shown a synergistic benefit in the removal of tattoo pigmentation.
Cosmetic Indications. Though the laser was initially embraced by plastic surgeons for reconstructive purposes, the use of laser technology for cosmetic indications has become increasingly frequent over the last two decades. The ideal nonsurgical treatment method for aesthetic indications is dependent on each patient’s skin type, goals, recovery time priorities, threshold for complications, and aesthetic expectations. Equally important is the consideration of the surgeon’s experience and familiarity with a particular laser modality. The ideal treatment modality induces an improvement in the appearance of the skin with minimal skin injury. The most common indication for aesthetic laser application is the treatment of the signs of photoaging, such as wrinkles, dyspigmentation, elastosis, increased vascularity, and precancerous lesions such as actinic keratoses. Less frequent are the requests for the treatment of acne and surgical scars, contour abnormalities, and striae. Although dermabrasion and chemical peels can achieve similar results at significantly lower cost, the public’s fascination with high-tech therapy has created a high demand for lasers and equally high expectations of wrinkle ablation, pigment correction, and skin tightening. Currently, there is a plethora of laser technologies available for aesthetic applications. Due to the confusing nature of laser nomenclature and company branding efforts, it is best to categorize these lasers by their differential effects on tissue, specifically as ablative versus nonablative and fractional versus non-fractional. Ablative lasers (CO2 and erbium:YAG), which until recently were the standard of care, are those that vaporize the epidermis during treatment, when compared with nonablative lasers that do not vaporize the skin and require epidermal cooling. Nonablative lasers (e.g., Nd:YAG) are generally safer but less efficacious that ablative lasers, requiring multiple treatments to achieve a less robust result than ablative lasers. Fractional lasers treat the tissue with numerous microscopic patterned beams leaving a cuff of untreated tissue between the treated sites, permitting faster re-epithelialization from islands of undamaged tissue. This is in contrast to non-fractional lasers that treat the entire targeted tissue with a continuous beam. The fractional beam technology can be applied to lasers of different wavelengths and therefore fractional lasers can be ablative or nonablative in nature. The rapid evolution of new lasers over the past decade, especially the nonablative and fractional classes, is largely in response to an effort to decrease the recovery time and complications from traditional lasers (ablative non-fractional).11
Ablative Non-fractional Thermolysis. The ablative CO2 and erbium:YAG lasers were the first to be used for cosmetic laser skin resurfacing for the signs of photoaging and remain the main players in classic laser resurfacing. Both lasers are used in multiple passes, with each pass removing a controlled depth of skin, namely, the epidermis, followed by the papillary dermis and in certain situations, a portion of the reticular dermis. The treatment stimulates the formation of new and rejuvenated skin layers, as well as new collagen formation and collagen contraction resulting in improvement of rhytids, skin laxity, and irregularity and hyperpigmentation. In the appropriate patient, this treatment is extremely effective; however, it is not a substitute for rhytidectomy. One advantage to laser skin resurfacing over dermabrasion or deep chemical peels is that the treatment is almost blood-free, because the heat of the laser coagulates the dermal vessels. This permits accurate visualization of the depth of penetration from the pink papillary dermis to the yellow “chamois” reticular dermis, which is the typical endpoint of therapy. Furthermore, the laser hand piece may offer more uniform skin ablation compared with a dermabrasion burr or topically applied acid.
In preparation for ablative non-fractional thermolysis, pre-treatment with 1 month of topical retinoic acid and hydroquinone is commonly prescribed to promote faster re-epithelialization and to avoid post-laser hyperpigmentation, respectively. When treating the perioral area, antiviral medications are recommended as prophylaxis against the herpes infections that can cause significant scarring. Patients should be advised that complete wrinkle removal is not possible and that laser skin resurfacing is not a substitute for surgery. Moderate wrinkle effacement with improvement in hyperpigmentation is a realistic goal with this treatment. The erbium:YAG laser light has a greater affinity for water than CO2, and therefore, the depth of penetration is more shallow than the CO2 laser. Despite faster healing and a decreased risk of prolonged erythema, the results with the erbium:YAG laser are generally less robust because of the reduced tissue penetration. More aggressive use of the erbium:YAG laser with longer pulses can achieve results comparable to the CO2 laser. Potential complications include infection, scarring, hypopigmentation, prolonged erythema, ectropion, and unpredictable alterations in skin tone and texture. Ablative non-fractional thermolysis is contraindicated in actively infected skin, recent (<12 months) history of isotretinoin/acitretin use, darker Fitzpatrick skin types, and history of keloids. Finally, this treatment should be limited to the facial skin and not be used on the thinner skin of the neck, chest, or hands.12
Fractional Ablative Photothermolysis. Fractional thermolysis was introduced in 2003 as a new technology that attempts to maintain the efficacy of non-fractional lasers while decreasing recovery time and risk profile. Though fractional technology was initially applied to nonablative lasers, its most successful application to date has been in ablative lasers (CO2 and erbium:YAG). In fractional ablative lasers, the laser beam is divided into thousands of microscopic columns that deliver energy to the treated area as thousands of ablative microthermal treatment zones (MTZs), avoiding confluent ablative epidermal damage (Figure 18.7). Depending on the treatment parameters, up to 95% of the treated area may remain undamaged. Because each MTZ is surrounded by undamaged tissue, there is rapid repopulation and collagen remodeling of the treated area resulting in markedly faster healing. Fractional ablative lasers have been used successfully for aesthetic indications, including the treatment of photoaging (fine and moderate rhytids, skin irregularity, and laxity), melasma, dyschromias, and acne-induced and other types of scars (Figure 18.8). The safety profile of fractional ablative lasers is much improved over traditional ablative lasers, with lower risks of scarring, hypopigmentation, and infections. Consequently, fractional ablative lasers can be used in patients with higher Fitzpatrick skin types and applied to areas such as the neck, chest, back, and extremities, cases in which traditional ablative lasers were not recommended. One should not presume fractional laser technologies are risk-free. Though much less common, there are reports of complications, including prolonged erythema, dermatitis, purpura, infection, pigment alterations, and scarring after fractional treatments.13 Most fractional ablative laser treatments can now be conducted in the office setting with topical anesthetic creams in combination with oral sedatives. Depending on the treatment parameters, patients should expect a downtime of 1 to 7 days with erythema and swelling typically lasting 1 to 4 days and crusting up to 7 days on non-facial skin. As with traditional ablative treatments of the perioral area, prophylaxis against herpes infection with perioperative antiviral medication is recommended to prevent potentially significant scarring.14
FIGURE 18.7. Laser skin resurfacing. Treatment of perioral wrinkles and dyspigmentation with fractional CO2 laser. A. Pretreatment. B. Immediately after treatment with punctate bleeding from MTZs. C. Two weeks post treatment.
FIGURE 18.8. Laser skin resurfacing. Treatment of facial rhytids and dyspigmentation with fractional CO2 laser. A and C. Pretreatment. D. Immediately after treatment. B and E. Six weeks post treatment. Note the improvement of solar lentigines and softening of periorbital wrinkles.
A large number of branded fractional ablative lasers (CO2 and erbium:YAG) have become available in recent years. Though a thorough discussion on the specifics of each type of laser is beyond the scope of this chapter, it will suffice to say that patient selection remains key. Additionally, because of the multiple subtleties in fractional technology, a thorough understanding of the nuances of laser settings, including pulse energy, density, number of passes, and number of treatments for each clinical and anatomical application, as well as appropriate device selection, is critical for safe and efficacious treatment. As with non-fractional CO2 and erbium:YAG lasers, the fractional CO2 lasers have been found to produce more robust effects and higher patient satisfaction than the fractional erbium:YAG lasers, albeit with a slightly longer recovery time.15
Nonablative Non-fractional Photothermolysis. In contrast to ablative laser rejuvenation procedures, nonablative non-fractional laser rejuvenation procedures induce a dermal healing response via delivery of heat without ablation, or injury to the epidermis. Consequently, the nonablative non-fractional category of lasers is considered safer than ablative lasers, though also less efficacious. The exact mechanisms of nonablative dermal remodeling have yet to be completely understood. It is hypothesized that nonablative lasers exert their effect via injury to the dermis and/or the dermal vasculature resulting in a wound repair response, fibroblast stimulation, and collagen reformation. Nonablative treatments, while desirable due to higher safety profile and easier patient recovery, have yet to replace classic ablative resurfacing techniques or standard surgical procedures for facial rejuvenation. Nonablative resurfacing techniques are best suited for patients who only require modest rejuvenation of the aging face, as the improvements in fine lines, wrinkles, and dyschromias produced by nonablative lasers are subtle and gradual. Because the epidermis remains grossly intact with nonablative laser treatments, these lasers can be used for more delicate procedures such as periorbital, neck and chest rejuvenation, as well as for the treatment of superficial acne scars and other types of scarring. Nonablative lasers can also be quite effective for the treatment of solar lentigines, rosacea, telangiectasias, or spider angiomata. Most patients require two to three treatments for sufficient improvement. Patients with moderate-to-severe rhytids or photodamage are poor candidates for nonablative resurfacing and will benefit most from surgical or ablative skin resurfacing procedures. Nevertheless, nonablative non-fractional lasers may provide a reasonable compromise for the patients who cannot tolerate the downtime of more aggressive procedures and are not satisfied with the minimal improvements achieved via superficial chemical peels or microdermabrasion.16
There are numerous nonablative non-fractional lasers on the market. Some of the more commonly used lasers in this category are the KTP laser (532 nm), pulsed dye laser (585 and 595 nm), IPL devices (515 to 1,200 nm), Nd:YAG lasers (1,064 nm Q-switched, 1,064 nm long-pulse, 1,319, and 1,320 nm), diode lasers (980 and 1,450 nm), and Er:glass laser (1,540 nm). The mid-infrared devices, including 1,320, 1,450, and 1,540 nm lasers, seem to be the most effective for wrinkle and acne scar reduction. Red color and vascular lesions are best treated by hemoglobin-selective devices, such as the KTP, pulsed dye, and long-pulsed Nd:YAG lasers. Though the KTP has efficacy for pigmentation as does the Q-switched Nd:YAG laser, the IPL devices, by virtue of their broad emission spectrum, appear to be the most effective for simultaneous treatment of both red and brown lesions.
Fractional Nonablative Photothermolysis. Fractional nonablative lasers first became available in 2003. As discussed above, the fractional technology separates the laser beams into thousands of columns producing an array of MTZs, permitting faster healing at the cost of a less vigorous effect. There are an ever increasing number of fractional nonablative devices on the market based on the Nd:YAG, Er:glass, infrared, erbium fiber, and radiofrequency wavelengths. The public quickly embraced this class of lasers mostly due to decreased downtime. Fractional nonablative lasers have the same indications as non-fractional nonablative lasers. These devices have been used successfully to treat mild photoaging (dyschromias, elastosis, and fine rhytids) on the face, neck, chest, back and extremities, melasma, acne and other scarring, telangiectasias, and other superficial vascular lesions. Multiple treatments are typically required to achieve a significant result. Because newer fractional ablative lasers have been shown to be more effective in treating photoaging and scarring than fractional nonablative lasers, the latter are best suited to the treatment of chromophore-specific targets such as dyschromias and vascular lesions.
All surgical lasers are considered to be class IV devices: high-power lasers that are hazardous to view under any conditions (directly or diffusely scattered) and are a potential fire and skin hazard.17 The American National Standards Institute requires the laser key to be stored separately from the laser to prevent unauthorized use.
Patients and all personnel present must wear wavelength-specific safety goggles. There should be a limited number of entrances to the laser suite, each marked clearly with a laser warning sign. An extra pair of safety goggles should be left outside the door in areas of high traffic such as an operating room. If one is treating around the eyes, corneal eye shields are necessary. The patient should be further protected with wet drapes or crumpled aluminum foil (to reduce the risk of reflected laser light) when using the carbon dioxide laser. A laser-safe endotracheal tube should be used when using a laser in or around the oral cavity. The lowest possible FiO2 should be administered to decrease the risk of an inhalation or flash burn. Exhaled oxygen can ignite singed nasal or lip hairs when using the carbon dioxide, pulsed yellow dye, or hair removal lasers in the setting of enriched oxygen delivery.
Lasers that create significant laser plume, such as the carbon dioxide laser, should be used with a plume evacuator to prevent potential transmission of live virus particles into the airway of treating personnel. When treating warts, an N95 mask or respirator is also highly recommended in addition to the plume evacuator, and the potential viral contamination can be reduced by shaving the bulk of the wart prior to laser vaporization of the base. Lastly, the use of an expensive laser to treat conditions outside its capabilities or exaggeration or falsification of the treatment outcome for monetary gain is unethical and medicolegally dangerous. Patients should have a realistic understanding of the expected results and the risk of treatment, as well as other treatment options.
1. MacCormack MA. Photodynamic therapy in dermatology: an update on applications and outcomes. Semin Cutan Med Surg. 2008;27(1):52-62.
2. Burns AJ, Navarro JA. Role of laser therapy in pediatric patients. Plast Reconstr Surg. 2009;124(1 Suppl):82e-92e.
3. Hennidige AA, Quaba AA, Al-Nakib K. Sturge-Weber and dermatomal facial port-wine stains: incidence, association with glaucoma, and pulsed tunable dye laser treatment effectiveness. Plast Reconstr Surg. 2008;121(4):1173-1180.
4. McGill DJ, MacLarren W, Mackay IR. A direct comparison of pulsed dye, alexandrite, KTP and Nd:YAG lasers and IPL in patients with previously treated capillary malformations. Lasers Surg Med. 2008;40(6):390-398.
5. Low DW. Management of adult facial vascular anomalies. Facial Plast Surg. 2003;19(1):113-130.
6. Miyazaki H, Kato J, Watanabe H, et al. Intralesional laser treatment of voluminous vascular lesions in the oral cavity. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;107(2):164-172.
7. Sharif MA, Lau LL, Lee B, Hannon RJ, Soong CV. Role of endovenous laser treatment in the management of chronic venous insufficiency. Ann Vasc Surg. 2007;21(5):551-555.
8. Gold MH. Lasers and light sources for the removal of unwanted hair. Clin Dermatol. 2007;25(5):443-453.
9. Burris K, Kim K. Tattoo removal. Clin Dermatol. 2007;25(4):388-392.
10. Bernstein EF, Bhawalkar J, Clifford J, Hsia J. Treatment of tattoos with a 755-nm Q-switched alexandrite laser and novel 1064 nm and 532 nm Nd:YAG laser handpieces pumped by the alexandrite treatment beam. J Drugs Dermatol. 2010;9(11):1333-1339.
11. Alexiades-Armenakas MR, Dover JS, Arndt KA. The spectrum of laser skin resurfacing: nonablative, fractional, and ablative laser resurfacing. J Am Acad Dermatol. 2008;58(5):719-737.
12. Brightman LA, Brauer JA, Anolik R, et al. Abative and fractional ablative lasers. Dermatol Clin. 2009;27:479-489.
13. Metelitsa AI, Alster TS. Fractionated laser skin resurfacing treatment complications: a review. Dermatol Surg. 2010;36:299-306.
14. Tierney EP, Kouba DJ, Hanke CW. Review of fractional thermolysis: treatment indications and efficacy. Dermatol Surg. 2009;35:1445-1461.
15. Cohen SR, Henssler C, Johnston J. Fractional thermolysis for skin rejuvenation. Plast Reconstr Surg. 2009;124(1):281-290.
16. Tierney EP, Hanke CW.: Recent advances in combination treatments for photoaging: review of the literature. Dermatol Surg. 2010;36:829-840.
17. Houck PM. Comparison of operating room lasers: uses, hazards, guidelines. Nurs Clin North Am. 2006;41(2):193-218, vi.