Lasers for treatment of melasma and post-inflammatory hyperpigmentation

Abstract

Hyperpigmentary disorders, especially melasma and post-inflammatory hyperpigmentation (PIH), cause significant social and emotional stress to the patients. Although many treatment modalities have been developed for melasma and PIH, its management still remains a challenge due to its recurrent and refractory nature. With the advent of laser technology, the treatment options have increased especially for dermal or mixed melasma. To review the literature on the use of cutaneous lasers for melasma and PIH. We carried out a PubMed search using following terms “lasers, IPL, melasma, PIH”. We cited the use of various lasers to treat melasma and PIH, including Q-switched Nd:YAG, Q-switched alexandrite, pulsed dye laser, and various fractional lasers. We describe the efficacy and safety of these lasers for the treatment of hyperpigmentation. Choosing the appropriate laser and the correct settings is vital in the treatment of melasma. The use of latter should be restricted to cases unresponsive to topical therapy or chemical peels. Appropriate maintenance therapy should be selected to avoid relapse of melasma.

Energy-based devices for treatment of melasma

“…Lasers have transformed the treatment of many conditions in dermatology, as well as in pigmentary pathologies. Despite the fact that many pigmentary disorders have obtained good results with this modality, the safety and efficacy of lasers for melasma is, till now, controversial [11,12] . Laser devices are often employed to treat pigmentary disorders through their photothermal, photomechanical, and ablative effects.…”

“…One of the most serious side effects is hypopigmentation. High fluences inducing direct phototoxicity and cellular destruction of melanocyte, as well as subthreshold additive effect of various doses, intrinsic unevenness of skin pigmentation, and non-uniform laser energy output, could be possible pathogenic processes for this depigmentation [11,20] . The QS Ruby laser (QSRL) at 694 nm is more selective for melanin than 1064-nm QSNY.…”

“…The absorption of melanin decreases as wavelength increases, but a longer wavelength results in deeper skin penetration. Shorter wavelengths (< 600 nm) destroy pigmented cells with lower energy fluences, while longer wavelengths (>600 nm) penetrate deeper and need more energy to induce melanosome destruction [11] . Pigment specificity of lasers also depends on pulse width.…”

“…Fractional photothermolysis creates microthermal zones and leaves most of the treatment area intact. The intact skin aids in the healing process via the extrusion of necrotic debris and the migration of keratinocytes [11,23] . Although the use of NAFL has become popular, there are still very few evidence-based data supporting it in melasma therapy.…”

“…These short pulse targets the small chromophore of melanin and generates photoacoustic effect that leads to melanin destruction [11][12][13][14][15][16] . The threshold for the photoacoustic damage of skin by Q-switched Nd:YAG laser (QSNY) light is between 1.6-5 J/cm 2 , which indicates that pigment destruction can occur without skin ablation.…”