Precautions for the use of Q-switched neodymium:yttrium-aluminium-garnet laser for treatment of melasma

Melasma is a common pigmentary disorder with therapeutic challenges. Laser toning, a repetitive treatment of skin with low fluence 1064-nm Q-switched neodymium:yttrium-aluminium-garnet laser, has been recently used for treatment of melasma in Asia. Its mechanism is based on the subcellular selective photothermolysis theory that low fluence Q-switched neodymium:yttrium-aluminium- garnet laser treatment influences only melanosomes without destroying the melanocytes. No response to treatment, rebound hyperpigmentation or mottled hypopigmentation has been reported during laser toning. Patients with increased vasculature and erythema are poor indicators for laser toning, and history of skin-coloring tattooing should always be determined prior to treatment due to risk of paradoxical darkening. Sensitive skin with erythema should be treated prior to laser toning in order to recover the skin barrier. It is important to use low fluence for laser toning, as high fluence with strong photoacoustic energy will disrupt the basement membrane, further aggravating melasma.