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Lasers and Light Devices in the Treatment of Cosmetic Pigmentary Disorders in Asian Skin
Pigmentation disorders are common in Asians. Asians are also more prone to develop post-inflammatory hyperpigmentation (PIH). Pigmentation disorders are cosmetically disfiguring in Asians and are a common reason for dermatology consultation in Asian countries. Most patients seek treatment for cosmetic reasons.
Introduction
The development of cosmetic lasers and other light-based devices have allowed for effective and safe treatment of many cosmetic pigmentary disorders which were previously not treatable. Such devices specifically target the pigmented lesion with minimal damage to the surrounding tissue (Anderson & Parrish, 1983; Bailin, 1985; Goldman, Blaney, Kindel, & Franke, 1963; Jones & Nouri, 2006). However, some pigmented lesions, such as Becker's naevus, café-au-lait macules, and naevus spilus remain recalcitrant to current therapies due to their innate biological nature.
In this article, the principles and clinical applications of the lasers and intense-pulse light (IPL) device in the treatment of the cosmetic pigmentary disorders commonly seen in Asians are highlighted.
Recent Advances in Treatment of Cosmetic Pigmentary Disorders in Asians
Nonpigment selective lasers, such as the carbon dioxide laser (10,600 nm) and the Er:YAG laser (2,940 nm), are primarily used for laser skin resurfacing (to treat wrinkles and scars) but may remove superficial pigmented lesions (e.g., seborrheic keratosis). Introduced 2 decades ago, ablative lasers are being replaced by pigment-selective lasers. The risk of post-inflammatory hyperpigmentation (PIH) and scarring from ablative lasers is high due to severe thermal damage and inflammatory changes, especially when used to treat pigmentary disorders. Recently, non-ablative and ablative fractional photothermolysis were introduced which cause minimal thermal damage and are associated with post-inflammatory pigmentation (Manstein, Herron, Sink, Tanner, & Anderson, 2004). However, these fractional resurfacing lasers are not pigment specific and are generally less effective for treating pigmentary disorders.
Pigment-selective lasers/light devices offer more precise removal of pigmented lesions with less risk of causing post-inflammatory pigmentation (Alster & Williams, 1995; Downs, Rickard, & Palmer, 2004; Jang et al., 2000; Kilmer, Wheeland, Goldberg, & Anderson, 1994; Todd, Rallis, Gerwels, & Hata, 2000; Tse, Levine, McClain, & Ashinoff, 1994). Such devices include:
- Q-switched ruby laser (694 nm, 25–40 nanoseconds).
- Q-switched alexandrite laser (755 nm, 50–100 nanoseconds).
- Q-switched Nd:YAG laser (1,064 nm, 5–10 nanoseconds) which can be frequency-doubled to emit green light at 532 nm of the same pulse duration.
- IPL (515/200 nm).
- Pulsed-dye laser (585/595 nm, 1.5 msec).
Not all pigmented skin lesions respond equally to lasers or light devices. Some pigmented lesions can be cleared effectively (such as lentigines and Hori's naevus), while others tend to recur shortly after treatment (such as Becker's naevus and café-au-lait macules) or are associated with PIH (such as melasma). Table 2 lists the common pigmentary disorders and their response to laser/IPL treatment.
Conclusion
Properly chosen wavelengths of light used with appropriate pulse durations can selectively alter pigmented cells and disrupt exogenous and endogenous pigment in a manner that leaves the adjacent skin intact and allows for the effective and safe treatment of many cosmetic skin pigmentary disorders which are common in Asian skin. Risk of PIH can be reduced with proper patient selection, appropriate laser/light device selection, and good peri-operative skin care.
By: Goh Chee Leok
