Chapter 252. Cosmetic Applications of Nonablative Lasers and Other Light Devices

Over the last 40 years, the explosive advancement of laser technology has revolutionized the treatment of numerous skin conditions. The principle of selective photothermolysis set forth in 1983 by Anderson and Parrish1 has formed the basis for the development of lasers that selectively target and destroy tissues containing water, hemoglobin, and pigment. Lasers exhibiting such selective action were first applied to improve various potentially disfiguring medical conditions such as port-wine stains, hemangiomas, and pigmented birthmarks. More recently, these same principles have been implemented in an effort to improve the cosmetic appearance of normal and aging skin. The principle of fractional photothermolysis (FP) set fort by Manstein and Anderson2 has further revolutionized nonablative and ablative resurfacing by improving safety and shortening patient recovery times. Because laser treatments target all aspects of photoaging, from ameliorating the appearance of fine and deep rhytides to softening skin texture and improving pigmentation and skin laxity, they are becoming an indispensable tool in the armamentarium of the cosmetic dermatologist. A thorough understanding of the benefits and limitations of each laser technique and the expectations and lifestyle of the individual patient allow the practitioner to achieve the most satisfying cosmetic results.

Skin rejuvenation by laser was originally performed with devices that resulted in the destruction or ablation of the epidermis and elements of the dermis. The demand for less invasive procedures with shorter recovery times than those of traditional ablative laser resurfacing has led to the development of nonablative laser surgery. Many of these systems emit light in the infrared portion of the electromagnetic spectrum (1,000–1,500 nm), which is absorbed by water in deeper tissues while leaving the epidermis intact. This type of dermal wounding stimulates new collagen and elastin formation, which can improve the appearance of skin with mild-to-moderate photodamage. In general, the results are not comparable to those achieved with ablative lasers, but many patients are willing to accept more modest clinical improvements in exchange for fewer side effects and shorter recovery times. The advent of fractional nonablative laser technology has enabled the delivery of higher energy fluences to treat a fraction of the skin surface. This technology generally allows more effective and safer treatments for photoaging compared to traditional nonablative lasers.

Patient Selection

Proper patient selection is the key to successful nonablative laser resurfacing (see Chapter 251 for ablative laser procedures). Patients with realistic expectations who have mildly to moderately photodamaged skin are the best candidates for nonablative procedures. Results from nonablative laser treatments are generally gradual and progressive, with textural irregularities and pigment irregularities improving more than rhytides. Patients who seek immediate dramatic results are likely to be disappointed with the overall clinical outcome. The practitioner must distinguish and educate patients on the difference between static and dynamic rhytides. Static rhytides in general respond more favorably and completely to laser therapy whereas dynamic rhytides are best addressed with appropriate injection of available botulinum toxin preparations.

Risks and Precautions

As with ablative laser resurfacing, the heat produced by nonablative systems can reactivate prior herpes simplex infections (Table 252-1). Patients with a strong history of herpes labialis should receive prophylactic oral antiviral medication before treatment. Although nonablative laser procedures have an extremely low risk of scarring, these risks are increased in patients who have received isotretinoin in the previous year. Therefore, these patients should not undergo nonablative resurfacing. Patients with darker skin phototypes may develop a temporary postinflammatory hyperpigmentation after nonablative laser treatment. In order to ensure a safe treatment and to minimize the risk of adverse reactions, practitioners must use appropriate energy settings and correct treatment techniques to avoid bulk heating (heat accumulation) and injury to the treatment area.

Patient Positioning

Nonablative laser resurfacing can be performed in the physician's office, with both the patient and clinical personnel wearing proper eye protection.

Equipment

Several visible-light lasers have been developed to target discrete chromophores to stimulate dermal remodeling (Table 252-2). One of the first approaches to photorejuvenation used pulsed dye lasers (PDL) emitting light at wavelengths of either 585 nm or 595 nm. The ability of PDL treatment to improve the appearance of hypertrophic scars, striae distensae, and acne scars suggests that PDL treatment stimulates new collagen formation. A small clinical study confirmed that a single treatment with a PDL (585 nm, 450 ms) induced clinical improvement in 75%–90% of mild-to-moderate rhytides and 40% of moderate-to-severe rhytides.3 Longer-wavelength lasers such as the 1,064-nm Q-switched neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, the 1,320-nm Nd:YAG laser, the 1,450-nm diode laser, and 1,540-nm erbium:glass laser have also been shown to induce dermal remodeling. Multiple treatments are necessary at 2- to 4-week intervals. The effects are often gradual due to ongoing collagen formation, which may occur up to 6 months after the last treatment.

Treatment with intense pulsed light (IPL) devices, which emit a broad, continuous spectrum of light from 515 nm to 1,200 nm, has been shown to successfully rejuvenate photodamaged skin. Filters can be placed over the beam to eliminate the shorter wavelengths, which target hemoglobin and melanin, depending on the clinical application. Studies have shown that IPL treatment produces substantial clinical improvement in the dyspigmentation and telangiectasias that are associated with photoaging but only mild improvement in rhytides.4

In contrast to visible-light lasers creating large sheets of thermal damage, the lasers used for fractional photothermolysis are mid-infrared (1,440 nm, 1,540 nm, 1,550 nm, 1,927 nm) devices that create columns of thermal injury to various depths into the dermis, similar to pixels in a digital photograph.5 The epidermis rapidly heals around these columns of thermal damage, which stimulate progressive collagen remodeling. Treatments are generally scheduled at 3- to 4-week intervals for a total of 3 to 6 sessions. Photodamage of the face, neck, chest, and hands; acne scars (Fig. 252-1); striae distensae (Fig. 252-2); and melasma have all been shown to respond to fractional photothermolysis.

Several nonablative devices that deliver energy deep into the dermis have been shown to cause skin tightening. The direct application of infrared light, with pretreatment and post-treatment contact cooling of the skin, has been shown to heat deep collagen to the point of contraction. In appropriate patients, this contraction results in a visible tightening of redundant skin. Skin tightening can also be achieved by the use of monopolar and bipolar radiofrequency devices generating electric current, which produces heat through resistance in the dermis. Periorbital rhytides and middle and lower face laxity generally require 1 to 3 treatments at 4-week intervals, with tightening noted 1–3 months after the last treatment6 (Fig. 252-3). A new infrared device that emits light at 1,100–1,800 nm in multisecond cycles has also been shown to induce skin contraction. Focused ultrasound has recently been incorporated into a device designed to generate dermal and subcutaneous heating with subsequent neocollagenesis in treated skin. Selective cryolipolysis is utilized by a novel noninvasive device to cool and selectively treat localized subcutaneous fat deposits.

Anesthesia

Nonablative laser procedures are generally more easily tolerated than ablative procedures. The degree and type of anesthesia required depends on the patient's pain tolerance and the amount of heat energy generated by the device. A topical anesthetic such as lidocaine or a eutectic mixture of lidocaine and prilocaine applied 1 hour before the procedure is usually sufficient. Forced-air cooling can also make the procedure more tolerable. Higher-energy procedures such as fractional photothermolysis occasionally require nerve blocks, oral or intramuscular analgesics, and anxiolytics.

Technique

Nonablative visible-light laser systems require different treatment parameters depending on the skin type and condition to be treated. To protect the epidermis, all of these devices are used in conjunction with a contact cooling handpiece or cryogen spray delivered several milliseconds before the laser pulse. IPL devices are used with various filters and at different energy levels depending on the desired treatment effect. A transparent water-based gel is used to protect the epidermis. Fractional photothermolysis is performed in the presence of forced-air cooling. Various density and energy settings are used depending on the indication and clinical endpoint desired.

Finally, tightening procedures are performed by holding the handpiece in firm contact with the treated skin. Several investigators have shown that multiple passes using radiofrequency at relatively low-to-medium energies are effective and more tolerable for patients than high-energy treatments.

Outcomes Assessment

Because nonablative laser treatments stimulate collagen remodeling over several months, objective clinical improvements after a series of treatments may take weeks or months to be achieved. Reassurance by the physician as well as the use of pretreatment photographs may help patients to better appreciate their progress. Setting realistic goals and targeting the aspects of photoaging that are important to the patient will also yield a more favorable outcome and enhance patient satisfaction.

Complications

Nonablative laser surgery is not without risks, but side effects are much milder than with ablative laser treatment. Depending on the treatment, patients may have erythema and edema, which resolves in hours to days. Rarely are treatments associated with blistering, transient hyperpigmentation, or scarring. In some cases, post-treatment hyperpigmentation has been caused by excessive use of cryogen spray but has resolved with topical bleaching agents. IPL treatment of tanned skin or darker skin phototypes should be used cautiously due to the increased risk of adverse events including blistering, hypopigmentation, and scarring. To avoid reactivation of latent herpes simplex virus (HSV) infections with fractional resurfacing, appropriate oral antiviral prophylaxis should be considered for all patients regardless of reported HSV status.

Patient Instructions

Because the epidermis remains intact after nonablative laser procedures, minimal postoperative care is required. Ice can be applied to decrease erythema and swelling, and occasionally systemic glucocorticoids may be required.

A wide range of vascular lesions are amenable to safe and effective treatment by a class of lasers that take advantage of the principle of selective photothermolysis (see also Chapter 239).

Patient Selection

Vascular lesions can be a significant cosmetic concern for some patients and are generally amenable to laser treatment. Telangiectasias are small, superficial cutaneous blood vessels often appearing on the nose, cheeks, and chin in fair-skinned individuals as a result of actinic damage or rosacea. Other causes of telangiectasias include collagen vascular disease, genetic disorders, hormonal disorders, primary cutaneous disease, and radiation dermatitis. Telangiectasias are often associated with facial erythema, which can manifest as a flushing or blushing disorder. Various laser treatments can target this background erythema in addition to treating the discrete vascular lesions.

Other types of vascular lesions, including cherry and spider hemangiomas, venous lakes, and angiokeratomas, may respond to vascular laser treatment (Fig. 252-4). Poikiloderma of Civatte, which manifests as a combination of telangiectasia, irregular pigmentation, and atrophic changes in fair-skinned individuals with actinic damage, can also be treated with vascular lasers. Extreme caution must be used when treating this condition, because overly aggressive treatment can worsen the atrophy and hypopigmentation.

In addition to improving vascular lesions, vascular laser treatments can improve the appearance of hypertrophic scars and keloids. Vascular lasers not only reduce the erythema by eliminating the underlying dilated microvasculature in a scar, they can also reduce the height of the scar and improve the skin surface texture. Multiple treatment sessions are required, and the treatment can be augmented by intralesional injections of corticosteroid with 5-fluourouracil. Newly formed atrophic scars, such as striae rubra, can sometimes be greatly improved with vascular laser treatment, whereas older lesions are less responsive.

Risks and Precautions

Laser treatment of vascular lesions is relatively safe but not without risks (Table 252-3). Higher-energy treatments or treatments with overlapping passes can result in atrophic or hypertrophic scarring. Alterations in pigmentation may result due to the concomitant absorption of 532-nm light by epidermal melanin. Patients with tans or darker skin types must be treated with caution to avoid pigmentary changes.

Patient Positioning

Most cosmetic vascular laser treatments are performed in the office. The patient's eyes are protected with laser surgery goggles or with intraocular metal eye shields if treatment around the eye is required. All clinical personnel must wear laser surgery glasses that specifically absorb the wavelength of light used in the treatment. Flammable gases and other materials must not be present, because vascular lasers are capable of igniting fires.

Equipment

Vascular lesions were one of the first targets of treatment with early lasers. These early lasers, such as the argon laser (488 nm, 514 nm), argon-pumped tunable laser (488–638 nm), copper and bromide lasers (578 nm), potassium-titanyl-phosphate (KTP) laser (532 nm), and krypton laser (568 nm), emitted continuous energy that was absorbed by oxyhemoglobin in cutaneous blood vessels (Chapter 239). Their use was limited because the continuous thermal energy often resulted in scarring and pigmentary alterations. The development of pulsed lasers in the 1980s allowed for more precise targeting of the oxyhemoglobin-containing vessels with less thermal and mechanical injury of surrounding tissues (Table 252-4). It is believed that pulsed energy delivered with short pulse widths causes intravascular cavitation, vessel wall fragmentation, and hemorrhage, whereas pulsed energy delivered over longer intervals causes intravascular coagulation and collagen contraction within the vessel wall and surrounding tissue. To reduce epidermal damage, all vascular lasers use an epidermal cooling system, with a cryogen spray or contact cooling.

The flashlamp-pumped PDL uses a high-power flashlamp to excite an organic dye (rhodamine) and produces a pulse of yellow light that is absorbed by oxyhemoglobin. The newer PDLs can deliver a variety of fluences over variable pulse durations (0.45–40 ms) to effectively treat many cosmetic conditions (see also Chapter 239). These PDLs can deliver high-energy, shorter pulses of light to treat striae distensae rubra, keloids, CVM, and infantile hemangioma. Purpura often results at these settings but resolves within 1–2 weeks. However, the device is most useful in treating facial erythema and facial telangiectasias at longer pulse durations that do not lead to purpura, which is a barrier to treatment for some patients.

The long-pulse, frequency-doubled Nd:YAG-KTP lasers emit a green 532-nm light that can also improve telangiectasias with minimal purpura. The current KTP lasers deliver energy with pulse durations of 1–100 ms through a fiberoptic handpiece with contact cooling. Although the 532-nm light is strongly absorbed by hemoglobin, the laser has a limited depth of penetration, which makes it useful for treatment of superficial facial vessels. Because melanin also absorbs 532-nm light, this laser should be used with caution in patients with darker skin phototypes.

Long-pulsed infrared lasers such as the alexandrite (755 nm), diode (800 nm), and Nd:YAG (1,064 nm) lasers allow deeper penetration into the skin, but their light is absorbed less specifically by hemoglobin than is the light of other vascular lasers (see also Chapter 239). There is still enough absorption, however, to treat superficial and deep reticular veins (up to 3 mm in diameter) in patients with a variety of skin types. More recently, multiplex lasers have been developed that sequentially deliver a PDL (595-nm) pulse followed by an Nd:YAG (1,064-nm) pulse at precise intervals. It is theorized that the first PDL pulse induces blood clot formation and methemoglobin conversion, which allows for greater absorption of the Nd:YAG energy. Studies are ongoing to delineate the cosmetic and medical indications for multiplex laser treatment.

IPL devices with cutoff filters that deliver increments of light ranging from 515–590 nm have been shown to be effective in the treatment of cosmetic vascular conditions. IPL devices produce a variety of fluences (up to 80 J/cm2) over 2–10 ns in single-, double-, or triple-pulse modes. The light is delivered by a fiber through an 8 × 15 mm or 8 × 35 mm glass window that is pressed directly against the skin. A coupling gel is applied to the skin before light application to protect the epidermis from overheating and improve light penetration. Compared with PDLs, IPL devices require a longer treatment session and potentially a greater number of treatments to achieve similar results.

Anesthesia

Vascular lasers and light sources used for cosmetic indications produce a brief stinging or burning sensation. Treatments are generally tolerated without anesthesia. Because discomfort can build with cumulative laser pulses, treatment of lesions with large surface areas may require topical anesthesia with a eutectic mixture of prilocaine and lidocaine or topical lidocaine. Topical anesthetics are removed a few minutes before treatment to reduce vasoconstriction and interference with laser light delivery. Rarely, local anesthesia with lidocaine or nerve blocks are required for full-face treatment.

Technique

The technique for treatment of vascular lesions will depend on the type and size of vessel to be treated and the patient's skin type. PDL treatments are delivered through a handheld fiber-optic device with a spot size ranging from 2–12 mm. The pulses are placed adjacent to each other with approximately 18% overlap to avoid missing areas between pulses. In general, lower fluences are used to treat macular lesions, whereas higher fluences are used to treat more hypertrophic lesions. At short pulse durations, a light gray discoloration of the treated area is the therapeutic endpoint, whereas at long pulse durations transient purpura lasting 1–2 seconds is the desired endpoint. Pulsed KTP laser treatment is delivered using a handpiece held perpendicular to the skin surface, and the vessels are traced individually at a speed that heats them without causing epidermal damage. Effective treatment will cause vessels to disappear with a subtle blanching effect.

IPL is delivered with a shorter-wavelength filter (515 nm) in single-pulse mode to treat fine superficial vessels in patients with skin phototype I. Longer cutoff filters (570–590 nm) and double- or triple-pulse modes are needed to treat large and deeper vessels. A layer of cool water gel 1–2 mm thick is applied to the skin, and then test spots are treated at increasing fluences until a faint erythema without epidermal damage is achieved. The individual pulses are applied adjacent to each other with minimal overlap. A second pass may be made perpendicular to the first pass to prevent reticulation.

Outcomes Assessment

The efficacy of laser and light treatment of vascular lesions depends on the caliber and depth of treated vessels. Small superficial vessels are more responsive than larger, deeper vessels. Lesions with a high blood flow, such as some spider angiomas, are also more difficult to treat. Patient response is assessed at 4–6 weeks after treatment, and treatments are repeated if necessary.

Complications

Immediately after treatment, patients may experience erythema and edema, which may last for the next 1–2 days. Patients who are treated with a PDL at short pulse durations will develop purpura, which gradually resolves in 1–2 weeks. Crusting, blistering, and scarring may result from overtreatment with any vascular laser. With all long-pulsed infrared lasers, adequate epidermal cooling is critical to minimizing the risk of epidermal damage and scarring. Given the overlapping absorption spectrum of epidermal melanin, vascular laser treatment can cause hyperpigmentation or hypopigmentation, but this is rarely observed. Suntanned patients and patients with darker skin phototypes should not be treated with KTP, PDL, or IPL devices.

Patient Instructions

Application of cold dressings or ice can help minimize the erythema and edema that develop in the first 24 hours after vascular laser treatment. Crusted or blistered areas should be treated twice a day with petrolatum until they have resolved. Patients requiring multiple treatments should wear sunscreen daily to prevent the risk of laser energy absorption by epidermal melanin in subsequent treatments.

Patient Selection

The treatment of pigmented lesions depends on the type of pigmented lesion being targeted, its anatomic location in the tissue, and whether the pigment is intracellular or extracellular within this tissue. The background skin color must also be considered so that treatment can be directed toward the abnormal pigment while leaving the normal pigmentation intact.

The success of cosmetic treatment of pigmented lesions also depends on certain patient factors. A complete medical history should be taken with specific emphasis on poor wound healing, postinflammatory hyperpigmentation, bleeding disorders, gold therapy, and isotretinoin use in the previous year. Should any of these factors be present, the surgeon should proceed with extreme caution. In addition, all pigmented lesions should be properly evaluated, and biopsy should be performed on any questionable lesions. Laser treatment does not yield tissue for histopathologic analysis. Before treatment, patients should be counseled that the lesion may require multiple treatments and the lesion may not clear completely.

Risks and Precautions

Pigmentary and textural changes are the most common complications observed when treating pigmented lesions (Table 252-5). Pigmentary changes occur more commonly in patients who are tanned or have darker skin phototypes. Transient hypopigmentation and, rarely, long-term depigmentation may develop. Hyperpigmentation has been reported in up to 16% of cases and is more commonly seen in patients with darker skin phototypes.7 To avoid pigmentary alterations, patients with tanned skin should be treated very cautiously, because this increases their risk of adverse effects. The risk of scarring is small, but the use of Q-switched Nd:YAG lasers at 1,064 nm may cause textural change, although this occurs in fewer than 5% of cases.

Patients and practitioners must also be aware that laser treatments can alter tattoo pigments, causing a local or systemic reaction. Local allergic reactions to cadmium sulfide and chromium have been reported, and patients with known allergies to these substances should generally not undergo laser treatment for tattoo removal. Q-switched lasers may also alter cosmetic tattoos containing ferric or titanium oxide pigment, creating an immediate paradoxical darkening. It is advised that these eyeliner and lip tattoos first be treated in test spots with single pulses and then observed 2 weeks later to assess clinical outcomes. Often ablative lasers are more effective at removing these lesions without the risk of paradoxical darkening.8

Patients should also be questioned regarding medications because Q-switched lasers have been reported to cause localized chrysiasis in patients who have received parental gold therapy.9 It is believed that the laser causes a physiochemical transformation of the gold pigments, similar to its darkening effect on cosmetic tattoos.

Patient Positioning

Most laser treatments of cosmetic pigmented lesions are performed in the office, with the patient and all clinical personnel wearing appropriate eye protection. The treatment site is thoroughly cleansed to remove all makeup, sunscreen, and topical anesthetic, which can hinder delivery of the laser energy. If alcohol has been used to clean the area, it must be thoroughly removed before laser treatment, because it could be a source of flash fire development. Because treatment with Q-switched 1,064-nm Nd:YAG lasers can cause some tissue and blood splatter, universal precautions should be followed at all times.

Equipment

Lasers used for the treatment of pigmented lesions (Table 252-6) can be categorized as highly selective Q-switched lasers, less pigment-selective lasers, and non–pigment-selective lasers. The Q-switched lasers, including the Q-switched ruby laser (694 nm), the Q-switched alexandrite laser (755 nm), and the Q-switched Nd:YAG laser (1,064 nm), are capable of targeting superficial epidermal and deeper dermal pigment. Epidermal pigment–based lesions can also be treated with the Q-switched frequency-doubled Nd:YAG laser (532 nm) and the flashlamp-pumped PDL (510 nm). Long-pulsed pigment-specific lasers, such as the long-pulsed ruby laser, long-pulsed alexandrite laser, long-pulsed diode laser, and long-pulsed Nd:YAG laser, have pulse durations in the millisecond range. These lasers have been shown to treat certain nevi by targeting nests of cells rather than individual melanosomes.10

Nonspecific ablative lasers such as the CO2 laser (10,600 nm) and erbium:YAG laser (2,940 nm) can remove pigmented superficial lesions secondary to their ablative actions. IPL devices can be used to treat mild pigmentary changes due to photodamage. Fractionated 1,440 nm, 1,540 nm, 1,550 nm, and, more recently, 1,927 nm lasers have demonstrated efficacy for a variety of dermal and epidermal pigmentary disorders. The 1,927 nm wavelength creates superficial thermal injury ideally suited for resurfacing of epidermal pigmentary disorders.

Anesthesia

Treatment of the majority of pigmented lesions does not require topical or infiltrative anesthesia. However, treatment of larger tattoos and lesions with large amounts of dermal pigment may require local anesthesia or nerve blocks.

Technique

Superficial epidermal pigmented lesions such as ephelides, solar and labial lentigines, café-au-lait macules, and flat pigmented seborrheic keratoses can be effectively treated with Q-switched ruby (694-nm) lasers, Q-switched alexandrite (755-nm) lasers, 532-nm lasers, short-pulsed dye (510-nm) lasers, and IPL devices (Fig. 252-5; see also Chapter 239). Most lesions respond to 1 or 2 treatments spaced 4–6 weeks apart. The response of café-au-lait macules is variable, with up to a 50% recurrence rate. In general, the laser handpiece is held perpendicular to the skin, and parameters are selected based on the melanin content of the lesion and background skin type. Lower fluences are used for targets containing an abundance of melanin. The desired endpoint is a uniform but faint whitening of the skin without epidermal disruption.

Dermal pigmented lesions such as nevus of Ota and pigmentation due to medication can also be improved with the Q-switched pigment-targeted lasers described previously in Equipment. Dermal tattoos are generally treated with lasers that are selective for the various colors of inks (see also Chapter 239). Q-switched ruby and alexandrite lasers are best for treating blue, black, and green ink, whereas short-wavelength lasers such as the short-pulsed dye (510-nm) and Q-switched 532-nm ND:YAG lasers are best for treating red pigments. Yellow-pigmented tattoos are usually relatively resistant to Q-switched laser treatment. Dermal lesions and tattoos are treated similarly to epidermal lesions, with the desired endpoint being a whitening of the skin with intact epidermis. Treatments are spaced 6–8 weeks apart, because clearing of dermal pigment depends on the slow mechanism of phagocytosis (Fig. 252-6).

Outcomes Assessment

Patients should be evaluated 4–6 weeks after small test spots within the larger lesion are treated. They should be informed that often multiple treatments are needed to achieve the desired clinical outcome.

Complications

Immediately after laser surgery, the treated area develops a whitening response that typically fades in 20–30 minutes. Some patients may develop an urticarial reaction, which can subside within an hour and responds to antihistamines. A crust will form in the treated area; it resolves in 7–10 days on the face but may take longer to resolve on nonfacial areas. In rare cases, blisters, vesicles, scarring, and pigmentary changes may occur.

Patient Instructions

After laser treatment of pigmented lesions, patients may use ice packs, cool compresses, and hydro-occlusive dressings to reduce any postoperative pain. Daily cleansing of the treated areas with soap and water followed by application of occlusive ointments is recommended until the crusts have resolved. All patients are advised to avoid excessive sun exposure and apply broad-spectrum sunscreen daily.