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Lasers in Ethnic Skin
 

The use of lasers in ethnic skin can pose a therapeutic challenge due to significant risks of post-inflammatory pigment alteration in this patient population. The greatest risk occurs in lasers with wavelengths in the range of the absorption spectrum on melanin due to the epidermal melanin absorption and resultant thermal injury in richly pigmented skin. In this article we will review lasers that have been studied in ethnic skin and will offer a practical approach to the safe use of lasers in ethnic skin.


Laser Assisted Hair Reduction


The long pulsed Nd:YAG is the safest laser for hair removal in darker skin types. Two factors contribute to the safety of the long pulsed Nd:YAG in darker skin types.


First, the wavelength of the Nd:YAG (1064 nm) is at the end of the absorption spectrum of melanin. This wavelength is sufficient to achieve significant thermal injury in dark coarse hairs while sparing epidermal pigment. Secondly, 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 and sufficient epidermal cooling to occur.


The long pulsed Nd:YAG is the treatment of choice for hirsutism and psuedofollicultis barbae in African Americans with Fitzpatrick skin types V and VI. Due the typically coarse dark hair in this patient population, the long pulsed Nd:YAG is safe and highly effective at achieving permanent hair reduction after a series of treatments.1,2


Challenges with the long pulsed


Nd: YAG in darker skin types arise in those patients with dark skin but fine hair. This is typically seen in patient of Southeast Asian descent. 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 patients, 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 lasers, due to the elimination of irritation and dyschromia frequently seen with shaving, waxing or threading.


Fractional Devices


Nonablative fractional resurfacing offers patients with skin of color a novel treatment option for acne scars. There are several fractional devices available; however, the most extensively studied is the 1550-nm erbium-doped fiber laser (Fraxel, Reliant Technologies Inc., San Diego, CA). There are several published studies on the Fraxel in Asian skin. One study included Japanese patients with acne scars. One treatment consisted of four passes of the device to attain a final microscopic treatment zone of thermal injury with a density of 1,000 to 1,500/cm2. The fluence was set to 6 mJ. The treatment was repeated up to three times at 2– to 3-week intervals. Clinical improvement was achieved in all the patients. Rare adverse events included mild transient erythema. No patients showed scarring or hyperpigmentation as a result of treatment.3


Another study evaluated the 1550-nm erbium-doped fiber laser (Fraxel, Reliant Technologies Inc., San Diego, CA) for 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. In this study no patients developed hyperpigmentation.4


Although the safe and effective use of nonablative fractional resurfacing in Asian patients is well documented, there are few published studies in skin type VI or 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.5


Nonablative fractional resurfacing offers Asian patients with skin of color an excellent option to treat acne scars and photoaging. In both Asian and non-Asian patients with skin of color, conservative settings (low densities) are necessary to minimize the risk of hyperpigmentation.6


Nonablative Nd:YAG/Diode lasers


Other non-ablative devices have been studied in skin of color. One study comparing the 1320-nm Nd:YAG and the 1450-nm diode laser in the treatment of atrophic scars included skin types I-V. In this study, both devices offered clinical improvement without significant side effects.7


A short pulsed nonablative Nd:YAG (Laser Genesis, Cutera, Inc., Brisbane, CA) has been studied in skin types I-V for the treatment of acne scars. Settings were 14 J/cm2, 0.3 milliseconds, 7 Hz with a 5-mm spot size. Each side of the face was treated with a total 2,000 pulses. Nine patients were treated every 2 weeks for a series of eight treatments. Three blinded physician observers used photographs to rate scar severity. Using a grid on the pictures, observers counted scars at baseline and after the final treatment. Overall there was a 29% improvement in the scar severity score. Eight of nine patients reported improvement in their acne scars ranging from 10% to 50% improvement. Based on this study and observations from clinical practice, this nonablative Nd:YAG laser offers another safe and well tolerated option to treat acne scars in patients with skin of color.8


Skin Tightening


Many patients with skin of color seek treatment of skin laxity. In contrast to photoaging, increasing skin laxity with advanced age is equally common in all skin types. Older patients seek treatment for the jowls and nasolabial folds, which are a prominent sign of aging in this patient population. Younger patients seek treatment of the abdomen after pregnancy. Many patients with skin of color seek non-surgical interventions due to the significant risk of scarring in this patient population.


Radiofrequency. Radio frequency (RF) is electromagnetic radiation in the frequency range of 3 kHz to 300 GHz. These devices induce dermal heating, denature collagen and induce collagen remodeling. Wound healing mechanisms promote wound contraction, which ultimately clinically 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 periorbital area and jowls.9 Because RF energy is not dependent on a specific chromophore, epidermal melanin is not targeted and treatment of all skin types is possible.


Kushikata et al10 reported the use of RF in a series of 85 Asian patients of skin types III and IV. Blisters occurred in one patient, a burn occurred in one patient, and hyperpigmentation occurred in two of the 85 patients. The skin types of these patients were not specified; however, in all of these cases the complications were transient and healed without permanent sequelae. Objective physician evaluation found relatively good improvement at 3 months post-treatment, and even better improvement at the 6-month evaluation. The authors concluded that RF treatment was effective for skin tightening in Asian facial skin. RF offers safe and effective treatment of skin laxity in ethnic skin.


Infrared Tightening


Infrared light can also be used 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 pre-, parallel, and post-treatment cooling. With this device, improvements in skin laxity and facial and neck contours have been achieved.11


Chua et al investigated the use of infrared light (Titan, Cutera, Inc., Brisbane, CA) on 21 patients of Fitzpatrick skin types IV and V. At 6- month follow up, 86% of patients had improvement as measured by the physician assessment. They concluded that the Titan was effective in achieving mild to moderate gradual clinical improvement of facial and neck skin laxity. The procedure is associated with minimal downtime and is safe for use in darker skin, including skin types V and VI. 12


Infrared tightening can be used in all skin types with excellent safety. The settings range from 32J to 40J and are determined by patient tolerance and not the skin type. Liberal use of gel appears to improve patient tolerability. In all skin types, multiple sessions (three to five) are needed for best results.


Conclusion


Lasers can be challenging in skin of color. In this patient population, it is important to choose devices that have been studied and have demonstrated safety in skin of color. The lasers discussed in this discussion offer treatment options that have been shown to be safe and effective. Despite this, any laser in skin of color can cause significant complications if the appropriate settings are not utilized. 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.


Dr. Woolery-Lloyd serves as the Director of Ethnic Skin Care at the University of Miami Cosmetic Center with a particular interest in ethnic skin disease, including pigmentary disorders and keloids. She also specializes in lasers in ethnic skin.


References: 

1. Alster TS. Bryan H. Williams CM. Long-pulsed Nd:YAG laser-assisted hair removal in pigmented skin: a clinical and histological evaluation. Arch Dermatol. 2001;137(7):885-9. 2. Ross EV, Cooke LM, Timko AL, Overstreet KA, et al. Treatment of pseudofolliculitis barbae in skin types IV, V, and VI with a long-pulsed neodymium:yttrium aluminum garnet laser. J Am Acad Dermatol. 2002;47(2):263-7. 3 Hasegawa T, Matsuka T, Mizuo Y, et al. Clinical trial of laser device called fractional photothermolysis system for acne scars. J Dermatol. 2006;33(9);623-27. 4. Lee HS, Lee JH, Ahn G, Lee DH, Shin J, Kim DH, Chung JH. Fractional photothermolysis for the treatment of acne scars: a report of 27 Korean patients. J Dermatol Treatment. 2008;19(1):45-9. 5. Graber EM, Tanzi EL, Alster TS. Side effects and complications of fractional laser photothermolysis: experience with 961 treatments. Dermatol Surg. 2008; 34(3):301-5; discussion 305-7. 6. Kono, Chan HH, Groff W, Manstein D, Sakurai H, Takeuchi M, Yamaki T, Soejima K, Nozaki M. Prospective direct comparison study of fractional resurfacing using different fluences and densities for skin rejuvenation in Asians. Lasers Surg Med. 2007;39(4):311-4. 7. Tanzi EL, Alster TS. Comparison of a 1450nm diode laser and a 1320nmNdYAG laser in the treatment of atrophic facial scars: a prospective clinical and histological study. Dermatol Surg. 2004;30(2pt1):152-7. 8. Lipper GM, Perez M. Nonablative acne scar reduction after a series of treatments with a short-pulsed 1,064-nm neodymium:YAG laser. Dermatol Surg. 2006;32(8):998-1006. 9 Hsu TS, Kaminer MS. The use of nonablative radiofrequency technology to tighten the lower face and neck. Semin Cutan Med Surg. 2003;22:115–23. 10. Kushikata N, Negishi K, Tezuka Y, Takeuchi K, Wakamatsu S. Non-ablative skin tightening with radiofrequency in Asian skin. Lasers Surg Med. 2005;36(2):92-7. 11.Bunin LS, Carniol BJ. Cervical facial skin tightening with an infrared device. Facial Plast Surg Clin North Am. 2007;15(2):179-84. 12.Chua SH, Ang P, Khoo LS, Goh CL.Nonablative infrared skin tightening in Type IV to V Asian skin: a prospective clinical study. Dermatol Surg. 2007;33(2):146-51.



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