Ablative Devices

CO ₂ lasers have been used for the treatment of acne scars in ethnic skin; however, the laser’s usefulness has been limited by the risk of hyperpigmentation and scarring. For this reason, other modalities have been investigated for optimum acne scar treatment in ethnic skin.

Fractional Devices

Nonablative fractional resurfacing is used for photorejuvenation in all skin types and is especially useful for the treatment of acneiform scarring in ethnic skin. Nonablative fractional resurfacing is performed using a midinfrared laser, which creates microscopic zones of thermal injury, called microthermal zones (MTZs), with an energy-dependent diameter ranging from 100 to 160 μm. At the energies commonly used for facial rejuvenation (8–12 mJ/MTZ), the depth of penetration ranges from 300 to 700 μm. Relative epidermal and follicular structure sparing account for rapid recovery without prolonged downtime. Melanin is not at risk of selective, targeted destruction; therefore, fractional resurfacing has been used successfully in patients with skin of color.

There are several fractional devices available, with the most extensively studied being 1550-nm erbium-doped fiber laser (Fraxel, Reliant Technologies Inc, San Diego, CA, USA). In a study of the efficacy of this laser in Japanese patients with acne scars, one treatment consisted of 4 passes of the device to attain a final microscopic treatment zone of thermal injury with a density of 1000 to 1500/cm ² . The fluence was 6 mJ per microscopic treatment zone. The treatment was repeated up to 3 times at 2-week to 3-week intervals and clinical improvement was achieved in all the patients. Rare adverse events included mild transient erythema, whereas no patients showed scarring or hyperpigmentation as a result of treatment.

Another study evaluated the Fraxel for the treatment of acne scars in 27 Korean patients with skin types IV and V. Patient self-assessments demonstrated excellent improvement in 30%, significant improvement in 59%, and moderate improvement in 11% of patients. No patients developed hyperpigmentation.

Although the safe and effective use of nonablative fractional resurfacing in Asian patients is well documented, there are few published studies in skin types VI or in African American patients. In one retrospective review of 961 treatments in patients of all skin types, the rate of hyperpigmentation was 11.6% in skin type IV (n = 8) and 33% in skin type V (n = 3). The ethnicities of these patients were not specified.

Nonablative fractional resurfacing represents a relatively safe and effective option for Asian patients with skin of color for the treatment of acne scars and photoaging. Patients of African descent have been less extensively studied; however, in these patients conservative settings (low densities) are necessary to minimize the risk of hyperpigmentation.

Nonablative Devices

In a study comparing the 1320-nm Nd:YAG and the 1450-nm diode laser in the treatment of atrophic scars of patients with skin types I to V, both devices led to clinical improvement without significant side effects.

A short-pulsed nonablative Nd:YAG (Laser Genesis, Cutera, Inc, Brisbane, CA, USA) has been studied in skin types I to V for the treatment of acne scars. Settings were 14 J/cm ² , 0.3 milliseconds, 7 Hz, with a 5-mm spot size. The study included 9 patients who were treated every 2 weeks for a series of 8 treatments. Each side of the face was treated with a total of 2000 pulses. Three blinded physician observers used a grid on pictures of the patients to count scars at baseline and after the final treatment. They found a 29% improvement in the scar severity score. Eight of 9 patients reported improvement in their acne scars ranging from 10% to 50% improvement. This nonablative Nd:YAG laser offers another safe and well-tolerated option to treat acne scars in patients of African descent. It is important to note that a series of 8 or more treatments are required to achieve improvement. This device has an excellent safety profile in all patients, including skin type VI, and is most effective in shallow acne scars. Deep ice-pick acne scars remain a challenge with all laser modalities in skin of color.

Light-Emitting Diode

Light-emitting diodes (LEDs) offer another advancement in visible spectrum, monochromatic light therapy for photoaged skin. Typically, LEDs in devices are arrayed in panels with each LED emitting visible light in a ± 10-nm to 20-nm band around the dominant emitted wavelength. Energy output is less than 25 W, representing a fluence of about 0.1 J/cm ² . The mechanism of this device is thought to act by targeting stimulation of fibroblast mitochondrial metabolic activity. In addition, concomitant upregulation of procollagen and downregulation of matrix metalloproteinase I has been demonstrated. Although there are no studies on LEDs in ethnic skin, based on the mechanism of action, these devices should be and are generally considered safe in darker racial ethnic groups.

Alexandrite

The alexandrite laser has been studied in skin types IV to VI. In one study, a long-pulsed 755-nm laser with a 40-millisecond pulse width was used to treat 150 patients with skin types IV to VI. A test site with a fluence of 16 J/cm ² was first performed and energy fluence was selected according to response. A small complication rate (2.7%) was reported; however, only 2 patients with skin type VI were included in the study and both developed blistering. A smaller study of the alexandrite (755-nm, 3-millisecond pulse width) included 4 African American women with Fitzpatrick skin type VI. In this study, lower fluences were used (8–14 J/cm ² ) and no side effects were noted. Although treatment of skin types IV to VI is possible with the alexandrite, the associated risk is still great in these patients.

Diode

The Diode laser has been studied with greater success in the treatment of darker-skinned patients. The 800-nm diode laser was studied with pulse widths of 30 milliseconds and 100 milliseconds. Adrian and Shay reported that although both settings could be used safely, longer pulse widths (100 ms) allowed higher fluences to be used with fewer complications. Another study used the 810-nm Diode laser to treat 8 African American patients with skin types V and VI. These patients were treated with a lower fluence of 10 mJ/cm ² and a pulse width of 30 milliseconds. Despite the lower fluence, transient blistering and pigment alterations were noted in some patients. Overall, although the diode laser offers increased safety over the alexandrite laser in African American patients, complications remain an issue.

Nd:YAG

The long-pulsed Nd:YAG is the safest laser for hair removal in darker skin types, owing to 2 factors. First, the wavelength of this laser (1064 nm) is at the end of the absorption spectrum of melanin, and is sufficient to achieve significant thermal injury in dark coarse hairs while sparing epidermal pigment. Second, the adjustable pulse width of long-pulsed Nd:YAG lasers allows the laser energy to be delivered over a longer period of time allowing for the heat to dissipate with sufficient epidermal cooling.

The long-pulsed Nd:YAG is the treatment of choice for hirsutism and pseudofolliculitis barbae in African American patients with skin types V to VI, because of their typically coarse, dark hair. It is both safe and highly effective at achieving permanent hair reduction after a series of treatments.

Challenges with the long-pulsed Nd:YAG in darker skin types arise in patients with dark skin but fine hair. In these patients, permanent hair reduction is more challenging because the fluence and pulse width that are necessary to achieve permanent reduction of fine hair are risky in darker skin types. In these cases, it is important to educate the patient on the limitations of laser-assisted hair reduction. Patients must have realistic expectations and understand that lasers can offer an excellent hair-management program but may not offer permanent long-term removal of fine hairs. Many patients who fall into this category still prefer laser because of the elimination of irritation and dyschromia frequently seen with shaving, waxing, or threading.

Radiofrequency

Radiofrequency (RF) is electromagnetic radiation in the frequency range of 3 kHz to 300 GHz. These devices induce dermal heating, collagen denaturation, and collagen remodeling. Wound-healing mechanisms promote wound contraction, which ultimately enhances the appearance of mild to moderate skin laxity. One device (Thermacool, Thermage Inc, Hayward, CA) has reported efficacy in the treatment of laxity involving the lower face and neck. Because RF energy is not dependent on a specific chromophore interaction, epidermal melanin is not targeted and treatment of all skin types is possible.

Kushikata and colleagues reported the use of RF in a series of 85 Asian patients with skin types III and IV. Blisters occurred in 1, a burn occurred in 1, and hyperpigmentation occurred in 2 of the 85 patients. The skin types of these patients were not specified; however, in all of these cases the complications healed without permanent sequelae. Objective physician evaluation found relatively good improvement 3 months after treatment, and even better improvement at 6 months. RF treatment was concluded to be effective for skin tightening in Asian facial skin, offering safe and effective treatment of skin laxity. Although studies on RF have focused mainly on Asian skin, this modality has been widely used in African American patients with a similar safety profile.

Infrared Tightening

Titan (Cutera, Inc, Brisbane, CA, USA) is a device that uses infrared light to volumetrically heat the dermis. It is designed to thermally induce collagen contraction, with subsequent collagen remodeling and neocollagen synthesis. The epidermis is protected via pretreatment, parallel treatment, and posttreatment cooling with the sapphire tip. With this device, improvements in skin laxity and facial and neck contours have been achieved. It uses a long pulse of infrared light with a spectrum from 1100 to 1800 nm, with greatest intensity in the 1400-nm to 1500-nm range. The settings range from 32 to 40 J and are determined by patient tolerance and not by skin type. The penetration depth is 1 to 2 mm, which is best for targeting the reticular dermis. Light is emitted in multisecond cycles to sufficiently heat the dermis while providing appropriate cooling of the epidermis. Like other skin-tightening devices, it is designed to thermally induce immediate collagen contraction, followed by the induction of collagen remodeling and the synthesis of new collagen. Water is the target chromophore, which allows for uniform heating of the targeted area. The procedure causes mild to moderate discomfort and mild temporary erythema. Two to 3 initial passes are performed over the entire designated treatment area, with additional passes over areas of great concern. A series of 3 to 4 treatments, 4 to 6 weeks apart, is recommended for the best results. Although an immediate tightening effect is achieved, the full effect is observed 6 months after the last treatment. Liberal use of gel appears to improve patient tolerability. In all skin types, multiple sessions are needed for best results. Response rates are variable and can be influenced by patient selection.

In an open-label trial in 21 Asian patients, skin tightening was observed in 86% of patients as measured by 3 independent physician observers. This improvement ranged from mild to excellent (mild 29%, moderate 38%, excellent 19%). Variable response rates with skin-tightening technologies may be because of patient selection, energies used, and overall skin quality.

Another infrared device, the SkinTyte (Sciton, Inc, Palo Alto, CA, USA) delivers infrared light in the range of 800 to 1400 nm. It uses uniform, targeted deep dermal heating to achieve skin tightening. Continuous cooling of the epidermis is achieved with thermo-electric sapphire plates.

The LuxIR and the LuxDeep IR (Palomar Medical Technologies, Inc, Burlington, MA, USA) deliver infrared light in the range of 850 to 1350 nm. The LuxDeep IR Fractional Infrared handpieces (Palomar Medical Technologies, Inc) use fractional infrared light and were designed to deliver infrared deep light extending up to 6 mm into the dermis and fat layer without damaging the epidermis. The LuxDeep IR handpiece safely delivers more effective heat to greater depths, and offers longer pulse durations. The energy is delivered through a sapphire crystal with contact cooling to prevent epidermal injury. Several treatments are required. Clinical trials have demonstrated variable improvement in skin tightening.

Ultrasound Tightening

In cosmetic medicine, ultrasound has been used primarily for cellulite and fat treatment, but skin tightening is its newest target. Intense ultrasound (IUS) is an energy that can propagate through tissue up to several millimeters. Ultrasound waves induce a vibration in the molecules of a target tissue during propagation, and the thermoviscous losses in the medium lead to tissue heating. When the beam is directed in a firm focus of the skin tissue at a certain depth, it produces a thermal coagulative necrosis, leaving the superficial layers unaffected.

This type of intense ultrasound device has demonstrated to have the potential for correcting age-related sagging skin. Epidermal injury is minimized, and thermal energy is directed into the reticular dermis and subcutis, where immediate tissue contraction and delayed remodeling are believed to collectively cause tightening. It has been developed specifically for treating facial soft tissues and targeting the superficial musculoaponeurotic system (SMAS), a continuous fibrous network composed of collagen and elastic fibers that envelops the muscles of facial expression and extends superficially to connect with the dermis.

One device (Ulthera P, Ulthera Inc, Mesa, AZ, USA) was introduced for use in facial rejuvenation. It is a microablation device that noninvasively treats multiple layers of tissue. This device enables visualization of target layers of subepidermal tissue immediately before the therapeutic level of ultrasonic energy is delivered. The outer epidermal layer of skin is completely spared, while deeper treatment causes collagen denaturation and wound healing.

The use of intense ultrasound (IUS) energy targeting the SMAS was studied producing thermal injury zones (TIZs) in 6 unfixed human cadaveric specimens. There were 202 exposure lines delivered bilaterally in multiple facial regions by varying combinations of power and exposure time (0.5 to 8.0 J). Subsequently, the tissue was examined grossly and histologically for evidence of thermal injury. Investigators found evidence of focused collagen denaturation and shrinkage.

Alam and colleagues assessed the efficacy of ultrasound skin tightening in browlifting. After evaluating 35 subjects (median age of 44 years), the investigators found that a single ultrasound treatment of the forehead produced an average brow height elevation of slightly less than 2 mm. Most subjects responded well, with only transitory mild erythema and edema as side effects. It can be concluded that IUS appears to be a safe and effective modality for facial skin tightening. In addition, this modality is safe for African American patients because melanin is not a target.

Skin tightening via nonablative energy delivery offers reduction of skin laxity with minimal downtime, and no scars or serious adverse effects. All of the skin-tightening technologies discussed offer African American patients a safe alternative to surgery to treat skin laxity.

In summary, laser and light therapy can be used successfully in patients of African descent. In this patient population, it is important to choose devices that have been studied and have demonstrated safety in skin of color. Many of the lasers discussed in this article offer treatment options that have been shown to be safe and effective in dark skin. Despite this, any laser in the African American patient can cause significant complications if the appropriate settings are not used. When treating darker-skinned patients, the use of conservative settings to achieve the desired results is prudent. Following these guidelines, the clinician is most likely to achieve a favorable result with the least unwanted side effects.

Laser Hair Removal

Studies assessing intense pulsed light (IPL) for treatment of hirsutism in patients with darker skin types are limited. In a study of 210 subjects with skin types III to V, Bedewi reported no incidence of postinflammatory dyspigmentation, burning, or scarring with IPL photoepilation. In this series, if posttreatment edema or erythema developed, a topical steroid cream and an oral anti-inflammatory agent were administered.

In 26 patients (skin types V and VI) treated with photoepilation using modified light and heat energy system for a duration of 35 milliseconds, Sadick and Krespi reported that transient erythema (54%) was the most common AE reported, resolving at 6 weeks. In this study, 1 patient experienced a transient posttreatment burn with crusting and hypopigmentation in 1 treatment site, which resolved after 6 weeks. It was additionally reported that 8% experienced transient hypopigmentation that resolved after 12 weeks, and 8% experienced gradually fading hyperpigmentation that persisted at 6 and 12 weeks. No cases of blistering were reported.

Other complications of hair removal that have been reported include paradoxic hypertrichosis after treatment with alexandrite (755 nm) and IPL (590–1200 nm) devices. Although the incidence ranged only from 0.6% to 5.1%, it is suggested that individuals with darker skin types (phototypes III–V) may be at increased risk. The exact mechanism of photostimulation remains unknown, but it is speculated that low fluences can stimulate the transformation of vellus hairs into darker terminal hairs. This rare side effect of laser hair removal is less common in African American patients because of the tendency to have coarse (nonvellus) facial hair.

Persistent hypopigmentation has been observed with the alexandrite laser. In one study involving the long-pulsed alexandrite laser, on 150 subjects with skin phototypes IV to VI, an overall complication rate of 2.7% was reported. More severe complications, such as blistering, was reported in darker skin (phototype VI). In this study, 2 patients with skin phototype VI had AEs including blistering, hyperpigmentation, and hypopigmentation. A refrigerated gel was applied immediately before laser treatment. Also, subjects avoided the sun for 3 weeks before treatment, and were pretreated with sunscreen (SPF 15), as well as with a 2% hydroquinone/glycolic acid preparation nightly for 10 days before laser surgery. Hypopigmentation/hyperpigmentation, blistering, excoriation, crusting, ingrown hairs, and folliculitis were the main AEs reported. It was concluded that pretreatment with hydroquinone/glycolic acid and sun protection, as well as altering energy fluence, and epidermal cooling were effective in preventing hyperpigmentation. The use of topical corticosteroids, postoperatively, was considered essential in darker skin tones after treatment with the alexandrite laser.

In a study of 10 subjects (1 with skin phototype VI) treated with the super-long-pulsed 810-nm diode laser, the AEs observed included erythema, purpura, epidermal whitening, blistering, Nikolsky sign, and pain. Hyperpigmentation (11%) and hypopigmentation (9%) were noted after 6 months of treatment and hypopigmentation generally occurred in patients with darker skin and in those who had been treated under the most aggressive settings (ie, 1000-millisecond pulse duration and 115 J/cm ² ).

Toosi and colleagues analyzed the efficacy and side effects of different light sources (including the 810-nm diode, the alexandrite and the IPL [cutoff filter of 650 nm]) on the face and neck of 233 subjects with skin phototypes II to IV. As expected, a correlation between skin phototype and side-effect incidence was seen, with a higher incidence occurring in those with darker skin phototypes.

As mentioned previously, the long-pulsed Nd:YAG is the safest laser for African American patients. The Nd:YAG laser has demonstrated the lowest incidence of side effects. This is because of the minimal epidermal melanin absorption at this wavelength. Alster and colleagues found a 5% incidence of transient dyspigmentation without fibrosis or scarring in 20 patients with skin phototypes IV to VI after a series of 3 monthly long-pulsed 1064-nm Nd:YAG laser treatments. The duration of the dyschromia was approximately 4 weeks. Blistering occurred in only 1.5% of patients, suggesting that hypopigmentation and hyperpigmentation occurred independent of blister formation.

Goh compared the safety and efficacy of the long-pulsed Nd:YAG laser to a noncoherent IPL system (590–1200 nm) for hair removal in 11 patients with skin phototypes IV to VI, where the Nd:YAG was applied to one half of the body and the IDL to the other. In this study, a lower rate of AEs was observed in the ND:YAG-treated patients (5/11) versus IPL-treated patients (3/11).

Tattoo Removal

Tattoos often consist of multiple pigments, and their removal may require the use of several wavelengths involving both the visible and near infrared spectrum. Tattoo treatment becomes even more difficult and unpredictable in patients with skin types IV to VI because of the presence of significant amounts of epidermal melanin that can absorb laser energy. For the removal of black-and-blue tattoo pigments, as well as purple and violet pigments, the Q-switched 694-nm ruby laser is effective but risky in darker skin types. Q-switched Nd:Yag lasers emit 2 wavelengths of light, 532 and 1064 nm, and remain the safest lasers in the treatment of blue and black tattoos in darker skin types. Side effects of laser tattoo removal on darker skin can be reduced by using the minimum fluence necessary to produce immediate lesional whitening, signaling the destruction of intracellular melanosomes. When treating type VI skin with the Q-switched Nd:Yag laser, a 3-mm spot size and fluences starting between 3.4 and 3.6 J/cm ² is recommended. Greater fluences resulting in pinpoint bleeding and tissue splattering are more likely to lead to transient hyperpigmentation, permanent hypopigmentation, and scarring.

Pigmented Lesions

Dermatologic conditions that result in altered skin pigmentation, such as melasma, postinflammatory hyperpigmentation, lentigines, and dermatosis papulosa nigra continue to be a primary concern among patients with darker skin tones.

IPL has been used for the treatment of melasma in patients with skin type IV. The response of melasma to irradiation with any specific laser is variable; a lack of response, worsening of the dyschromia, and recurrence are the most frequent outcomes. IPL treatment complications may result in IPL-induced melasmalike hyperpigmentation. Because of the clear risk of postinflammatory hyperpigmentation observed in Asian patients, IPL should be avoided in African American patients.

Fractional photothermolysis is currently the only laser modality approved by the Food and Drug Administration (FDA) for melasma. Similar to IPL, it carries a risk of postinflammatory hyperpigmentation, especially in individuals who may have hyperactive melanocytes. Because of the risk of hyperpigmentation with melasma, this laser should be considered only in recalcitrant cases.

Q-switched lasers produce photomechanical effects within the epidermis and are effective for treating both freckles and lentigines. Postinflammatory hyperpigmentation is the most common side effect and tends to resolve within a few months. Reported rates of postinflammatory hyperpigmentation associated with the use of Q-switched lasers in Asian individuals have ranged from 4% to 25%. In African American individuals, postinflammatory hyperpigmentation is likely to occur in a significantly higher proportion of patients.

Of the pigmented lesions that greatly affect darker skin phototypes, nevus of Ota is a condition that responds well to treatment with Q-switched ruby, alexandrite, and Nd:YAG lasers. Complications, such as postinflammatory hyperpigmentation, have been observed in most patients despite pretreatment with topical hydroquinone. Postinflammatory hypopigmentation is another common side effect of Q-switched lasers in African American patients.

Skin Resurfacing and Acne Scars

Cutaneous laser resurfacing can provide an effective means for improving the appearance of diffuse dyschromia, photoinduced rhytides, and atrophic scarring in patients with darker skin phototypes. Different studies have demonstrated that transient hyperpigmentation is the most common AE experienced after laser skin resurfacing. The incidence ranges from 68% to 100% among patients with the darkest skin types (IV). Hypopigmentation, on the other hand, tends to be long standing, delayed in its onset, and difficult to treat. Fortunately, it is observed far less frequently than hyperpigmentation. The excimer laser, as well as topical photochemotherapy, has shown some success in repigmenting these affected areas.

Nonablative devices are desirable therapeutic options for skin rejuvenation in those with darker phototypes. Ablative lasers have been used less often on African American individuals, because of the increased risk of transient and permanent dyspigmentation as well as scarring. Erbium:Yag and CO2 remain the gold standards for the treatment of photoaging in lighter skin types, but are not desirable in African American patients because of the increased risk of complications, including a long recovery period, scarring, and prolonged postinflammatory changes. Postinflammatory hyperpigmentation has been reported to occur in up to 68% of patients with skin type IV.

In general, when compared with standard ablative therapies, fractional resurfacing is associated with a reduced side-effect profile and faster recovery times. Usually the erythema and edema tend to resolve within a few days instead of lasting weeks to months.

Fractional laser photothermolysis (FP) treatment was evaluated in a retrospective study where 961 subjects with skin types I to V were treated with the 1550-nm erbium-doped laser. The most common complications were acneiform eruptions (1.87%) and herpes simplex outbreaks (1.77%). These side effects were equally distributed across different ages, skin types, body locations, laser parameters, and underlying skin conditions; however, the incidence of postinflammatory hyperpigmentation augmented with increasing skin type with the incidence of hyperpigmentation in skin types III, IV, and V was noted to be 2.6%, 11.6%, and 33.0%, respectively. When treating darker skin types with FP, it is better to reduce treatment energy and treatment density to minimize the possible prolonged erythema and edema as well as hyperpigmentation.

In one study, 15 subjects with acne scars and skin types IV to VI were treated using a 1550-nm erbium fractionated laser, with either 10 mJ or with 40 mJ. A significant improvement in the acne scarring and overall appearance was observed but significant postinflammatory hyperpigmentation was seen more often in those subjects with darker skin types.

Vascular Lesions

For the treatment of port-wine stains, hemangiomas, and facial telangiectasias, the 585-nm pulsed dye laser (PDL) has demonstrated superiority with regard to both effectiveness and safety, despite patient skin phototype. Although African American patients are more prone than those patients with lighter skin to develop pigmentary changes after PDL treatment, skin-cooling techniques can reduce the risk of dyspigmentation.