Cutaneous Lasers




There has been a remarkable development and evolution of laser technology, leading to adaptation of lasers for medical use and the treatment of skin problems and disorders. Many treatments that required incisional surgery and other invasive methods are now preferentially treated with a laser. Although laser advances have resulted in the availability of some amazing tools, they require the clinical skill and judgment of the clinician for their optimal use. This article provides a clinically oriented overview of many of the lasers valuable in facial plastic surgery. Basic science, clinical adaptations, and patient management topics are covered.


Key points








  • The CO 2 and erbium lasers have been widely used for skin resurfacing for improvement of the aging skin. These technologies have been used to correct rhytids, dyschromias, lentigenes, elastosis, and other sign of photoaging. Recent fractionation of these laser wavelengths has resulted in more rapid healing, less downtime, and a reduced frequency of complications.



  • Nonablative laser technology shows great promise and currently can produce significant improvements in fine lines and dyschromias.



  • Laser therapy of hirsutism, vascular lesions, and tattoos is superior to most of the previously applied treatment modalities.



  • A key to the safe and predicable use of lasers is in the selection of the optimal technology for the problem and patient being treated.






Introduction


Lasers are named for the medium that produces the wavelength of laser energy for a specific laser. The laser medium is contained within an optical cavity or resonator and may be a liquid, as in the case of a pulsed dye laser; a solid, as in the case of an erbium:yttrium-aluminum-garnet (YAG) laser; or a gas, as in the case of the carbon-dioxide (CO 2 ) laser. In a general design, photons from an energy source are made to move parallel to the axis of the optical cavity and are repeatedly reflected between opposing mirrors ( Fig. 1 ). The summation of this repetitive interaction causes a stimulated emission to be generated.




Fig. 1


Typical laser schematic.


Clinically, it is also helpful to describe the wavelengths of light at which particular lasers operate. These designations, such as “1064-nm neodymium (Nd):YAG,” guide the clinician to the appropriate use and improve documentation and communication. Critical parameters of the laser emission include the wavelength, pulse characteristics, and fluence. Some lasers transmit their laser energy to the operator’s handpiece by an articulated tube with mirrors, whereas other lasers transmit their energy by fiberoptic cable.


The following sections describe various lasers, along with their general physical characteristics and absorption spectra ( Table 1 ).



Table 1

Table of commonly used clinical lasers



























































Energy Source Wavelength Targeted Chromaphore Application
CO 2 10,600 nm Water Skin resurfacing
Erbium:yttrium-aluminum-garnet 2490 nm Water Skin resurfacing
Erbium:glass 1540–1550 nm Water Skin resurfacing
Erbium:yttrium-scandium-gallium-garnet 2790 nm Water Skin resurfacing
Neodynium:yttrium-aluminum-garnet 1440 nm/1064 nm Water
Red-green-brown pigment
Blue-black pigment
Skin resurfacing
Tattoo removal, hair removal (pigmented skin)
Q-switched potassium-titanyl-phosphate Frequency-doubled neodynium:yttrium-aluminum-garnet 532 nm Hemoglobin
Melanin
Red pigment
Vascular lesions
Pigmented lesions
Tattoo removal
Q-switched ruby 694 nm Melanin, dark blue-black pigment
Green pigment
Tattoo removal
Q-switched alexandrite 755 nm Melanin, black-blue pigment ± red-green pigment Tattoo removal, hair removal
Pulsed dye laser 585–595 nm Oxyhemoglobin Vascular lesions
Pulsed diode 800–810 nm Melanin Tattoo removal, hair removal (fair skin)




Introduction


Lasers are named for the medium that produces the wavelength of laser energy for a specific laser. The laser medium is contained within an optical cavity or resonator and may be a liquid, as in the case of a pulsed dye laser; a solid, as in the case of an erbium:yttrium-aluminum-garnet (YAG) laser; or a gas, as in the case of the carbon-dioxide (CO 2 ) laser. In a general design, photons from an energy source are made to move parallel to the axis of the optical cavity and are repeatedly reflected between opposing mirrors ( Fig. 1 ). The summation of this repetitive interaction causes a stimulated emission to be generated.




Fig. 1


Typical laser schematic.


Clinically, it is also helpful to describe the wavelengths of light at which particular lasers operate. These designations, such as “1064-nm neodymium (Nd):YAG,” guide the clinician to the appropriate use and improve documentation and communication. Critical parameters of the laser emission include the wavelength, pulse characteristics, and fluence. Some lasers transmit their laser energy to the operator’s handpiece by an articulated tube with mirrors, whereas other lasers transmit their energy by fiberoptic cable.


The following sections describe various lasers, along with their general physical characteristics and absorption spectra ( Table 1 ).



Table 1

Table of commonly used clinical lasers



























































Energy Source Wavelength Targeted Chromaphore Application
CO 2 10,600 nm Water Skin resurfacing
Erbium:yttrium-aluminum-garnet 2490 nm Water Skin resurfacing
Erbium:glass 1540–1550 nm Water Skin resurfacing
Erbium:yttrium-scandium-gallium-garnet 2790 nm Water Skin resurfacing
Neodynium:yttrium-aluminum-garnet 1440 nm/1064 nm Water
Red-green-brown pigment
Blue-black pigment
Skin resurfacing
Tattoo removal, hair removal (pigmented skin)
Q-switched potassium-titanyl-phosphate Frequency-doubled neodynium:yttrium-aluminum-garnet 532 nm Hemoglobin
Melanin
Red pigment
Vascular lesions
Pigmented lesions
Tattoo removal
Q-switched ruby 694 nm Melanin, dark blue-black pigment
Green pigment
Tattoo removal
Q-switched alexandrite 755 nm Melanin, black-blue pigment ± red-green pigment Tattoo removal, hair removal
Pulsed dye laser 585–595 nm Oxyhemoglobin Vascular lesions
Pulsed diode 800–810 nm Melanin Tattoo removal, hair removal (fair skin)




Lasers for the treatment of skin aging


Ablative Resurfacing


The CO 2 10,600-nm laser


The CO 2 laser became popular for skin resurfacing in the early 1990s and has been the most widely used laser for ablative resurfacing. In many ways, the dramatic results obtained by the full ablative CO 2 laser still represent the gold standard by which other resurfacing modalities are compared. However, its wide application has decreased because of the resulting prolonged healing time. The CO 2 laser emits invisible infrared radiation at a 10,600-nm wavelength. This wavelength is primarily absorbed by intracellular and extracellular water, resulting in several thermal effects, such as tissue necrosis, vaporization, carbonization, and coagulation. Clinically, CO 2 lasers have been applied in the treatment of a variety of cutaneous disorders including age-related photodamage, rhytids, and depressed scars ( Fig. 2 ).




Fig. 2


Clinical photographs of patient after nonfractionated ablative CO 2 10,600-nm laser resurfacing. ( A ) Preoperative. ( B ) Postoperative.


The use of fractionated CO 2 technologies was reported after 2007. Similar to the fractionated erbium technologies that preceded, fractionated CO 2 technologies are based on the concept that cylinders of tissue are treated with laser energy while leaving interspersed areas of untreated tissue. As with the fractionated erbium technologies, this creates a productive balance between favorable tissue effects, such as correction of epithelial architecture and skin tightening, while reducing the propensity for prolonged healing, erythema, and scarring ( Figs. 3 and 4 ).




Fig. 3


The fractionated pattern. ( A ) Schematic. ( B ) Clinical intraoperative photograph showing fractionated pattern.



Fig. 4


Clinical photographs of patient after fractionated 10,600-nm CO 2 resurfacing for correction of rhytids and lentigenes. ( A ) Preoperative. ( B ) Postoperative.


The erbium:YAG 2940-nm laser


The erbium laser was introduced for clinical use in the latter part of the 1990s. The second-generation erbium lasers possess favorable ablative and coagulation properties that make them favorable for skin resurfacing. Skin conditions that can be successfully treated with this laser include rhytids, solar elastosis, dyschromias, and actinic photodamage. The erbium:YAG laser has the highest absorption coefficient for water among ablative lasers. Given its particular tissue interaction characteristics, the erbium laser is touted to provide many of the benefits of CO 2 laser treatment with reduced unfavorable sequelae. This may be related to the favorable thermal relaxation times achievable with the erbium:YAG platforms compared with the CO 2 platforms. The fractionated algorithm further improves its therapeutic margin ( Fig. 5 ).




Fig. 5


Clinical photographs of patient after fractionated 2940-nm Er:YAG resurfacing for correction of rhytids and lentigenes. ( A ) Preoperative. ( B ) Postoperative.


Erbium:YAG versus CO 2 for photoaging


Rhytids, telangectasias, laxity, and actinic changes are characteristic signs of photoaging of the skin ( Table 2 ). These findings can be improved with ablative and nonablative resurfacing technologies. The erbium laser has been described to be more effective in the treatment of superficial dyschromias and other actinic changes in the superficial layers of the skin, whereas the CO 2 laser penetrates deeper and is more effective in the remodeling of the deeper layers of the dermis, causing the effacement of coarser rhytids. The major negative aspect of the use of CO 2 resurfacing is the prolonged healing time, prolonged erythema, and risk of hypopigmentation. Both lasers have been produced in fractionated platforms, allowing for an ability to adjust to a specific patient skin type and degree of photoaging. The result is a more measured effect, but a decreased downtime and healing time.



Table 2

The Glogou skin scale






















Glogau Photodamage Classification
Type 1 No wrinkles (age 20s to 30s) Minimal to no discoloration or wrinkling, no keratoses, no need for makeup
Type 2 Wrinkles with motion (age 30s to 40s) Wrinkling with movement, slight lines near eyes, no keratoses, need for some foundation or makeup
Type 3 Wrinkles at rest (age 50s to 60s) Visible wrinkles all the time, noticeable discolorations, visible keratosis, need for heavy foundation or makeup
Type 4 Only wrinkles (age 60s to 70s) Yellow or gray color to skin, wrinkles throughout, history of prior skin cancer, makeup unusable because of caking or cracking

Adapted from Glogau RG. Chemical peeling and skin aging. J Geriatr Dermatol 1994;2:5–10; with permission.


Other Superficial Ablative and Nonablative Lasers


The highly successful 1550-nm fractionated erbium laser expanded the use of erbium lasering for cosmetic and reconstructive indications. At this laser wavelength, patients could be offered a modest but significant improvement in texture, rhytids, and superficial lentigenes. The most significant benefit of this laser is the markedly reduced down time. However, because the results can be insufficient for several clinical conditions, the popularity of the fractionated CO 2 platforms continues.


Other superficial ablative and nonablative technologies are available for a spectrum of cutaneous applications. These lasers function at 2790 nm, 1440 nm, 1540 nm, 1550 nm, and 1064 nm, and other wavelengths. The clinical effect of these lasers and technologies is frequently not as dramatic as with the ablative and fractionated technologies described previously, but the science continues to change, and more effective platforms are being developed.


There are many nonlaser skin improvement technologies available that include plasma, radiofrequency, and ultrasound technologies. A full discussion of these technologies is beyond the scope of this article, and the authors urge readers to investigate those reports further.




Lasers for the treatment of benign pigmented lesions


The Nd:YAG laser produces laser energy at a wavelength of 1064 nm. It penetrates up to 2 to 3 mm into the dermis, making it useful in the removal of deeper dermal natural and artificial pigmentations. The 1064-nm wavelength of the Nd:YAG laser allows it to be helpful for the removal blue-black tattoos, but it is relatively poorly absorbed by green pigments. When the laser beam is passed through a KTP crystal, the laser energy frequency is doubled and the resultant light wavelength is halved to 532 nm. This wavelength is absorbed more superficially in the skin, making it useful for the removal of benign superficial epidermal pigmentations.


Lentigenes are frequently treated along with rhytids while doing ablative resurfacing. In the patient who does not need general ablative resurfacing, such as a younger patient, the lentigenes may be treated more directly. In cases where there is doubt about the diagnosis of the lesion, at least one area of the lesion should be biopsied. When one can be confident that the lesion is indeed benign, the Q-switched frequency-doubled Nd:YAG laser operating at 532 nm can produce good results ( Figs. 6 and 7 ).




Fig. 6


Clinical photographs of patient after Q-switched 532-nm frequency-doubled Nd:YAG laser treatment of lentigenes. ( A ) Preoperative. ( B ) Postoperative.



Fig. 7


Clinical photographs of second patient after Q-switched 532-nm frequency-doubled Nd:YAG laser treatment of upper eyelid and brow lentigenes and nevus, and 585-nm pulsed dye laser treatment of cheek telangectasias. ( A ) Preoperative. ( B ) Postoperative.




Lasers for tattoo removal


The removal of traumatic and cosmetic tattoo pigment can be effectively approached with lasers. Depending on the pigment, there are several lasers that are frequently used. Table 3 depicts the lasers that are effective for various pigments. These include the Q-switched ruby 694-nm laser; the Q-switched Nd:YAG (532 and 1064) laser; and the Q-switched alexandrite (755 nm) laser.



Table 3

A clinical guide to the management of various tattoo pigments and effective lasers












































































Color of Tattoo Ink Frequency-Doubled Nd:YAG (532 nm) Ruby Laser (694 nm) Alexandrite Laser (755 nm) Nd:YAG Laser (1064 nm)
Red ++++
Orange ++ + + ++
Yellow
Green ++ ++++ +++ +
Blue ++ +++ ++++ ++
Blue-black +++ ++++ ++++ ++++
Violet ++ + + ++
Tan ++
Brown + ++ ++ +
Black (amateur) +++ ++++ ++++ ++++
Black (professional) +++ ++++ ++++ ++++

Data from Parlette EC, Kaminer MS, Arndt KA. The art of tattoo removal. Plastic Surgery Practice Jan 18–20, 2008. Available at: www.plasticsurgerypractice.com/products/15374-the-art-of-tattoo-removal .


The use of laser technology for the removal or lightening of artificially placed pigment in the skin, or tattoos, has some similarities to the treatment of naturally occurring pigment lesions. The wavelength of the laser to be used depends on the target pigment in the tattoo. There are several caveats to the treatment, and it is advisable that the practitioner (except for the most experienced) use test spots to assess the patient and pigment response before proceeding with treatment of the entire lesion. Various patient factors are important to assess before treatment including whether or not the patient has recently tanned, because this has an impact on resultant hypopigmentation and hyperpigmentation. It is also advisable to pretreat the patient with an antiviral agent if the perioral area is being treated.


The Q-switched alexandrite laser at 755 nm, the Q-switched ruby laser at 694 nm, and the Q-switched Nd:YAG laser at 1064 nm can be effective in the treatment of lighter-skinned individuals with a dark blue or black tattoo pigment. In darker-skinned individuals (ie, Fitzpatrick skin types IV–VI [ Table 4 ]), the Q-switched Nd:YAG laser is preferred because the longer wavelength results in a greater degree of epidermal sparing. For tattoos exhibiting red pigment, the Q-switched Nd:YAG laser operating at 532 nm can be used. Because of the risk of hyperpigmentation and hypopigmentation, treatment is usually limited to light-skinned individuals. Green pigment is frequently difficult to treat and best treated with the Q-switched ruby 694 nm laser ( Figs. 8 and 9 ).


Aug 26, 2017 | Posted by in General Surgery | Comments Off on Cutaneous Lasers
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