Since the introduction of selective photothermolysis, Q-switched lasers have been used for the treatment of pigmented lesions. The Q-switched ruby, alexandrite and YAG lasers are highly effective in the treatment of dermal pigmented lesions, but in dark-skinned patients such as Asians, the risk of complications such as erythema, blistering and post-inflammatory hyperpigmentation are increased. Previous studies that compared the response of lentigines in Asian skin using Q-switched vs. long-pulsed lasers found that post-inflammatory hyperpigmentation was less when using longer pulses. Long-pulsed lasers and IPLs are effective with minimum complications. The lack of down time associated with the use of IPL can be of particular advantage for some patients, but to achieve a satisfactory outcome, several sessions are typically necessary. To balance cost-effectiveness and clinical outcome, one approach is to treat several test areas with different devices. Q switched lasers are the first line treatment of dermal pigmented lesions, such as nevus of Ota, Mongolian spots, ADM and tattoo. The QS Nd:YAG is considered particularly effective in dark skinned patients given its longer wavelength and lower risk of adverse effects. Complications such as post-inflammatory hyperpigmentation can occur and hypopigmentation becomes obvious according to the treatment sessions. Laser toning plays a role in melasma, however, melasma is still not completely curable. Picosecond lasers more effective than Q-switched lasers with fewer complications, but somewhat different from endpoint Q-switched laser, and further evidence needs to be accumulated in the future.

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The enduring benefits of q-switched lasers in the era of picosecond technology<br/><br/>Niwat Polnikorn1 , Harit Leksuksri 1, Pawit Phadungsakawasdi 2<br/>1Dr.Niwat’s Skin and Laser Clinic, Hua Hin, Prachuabkirikhan, Thailand<br/>2 Division of Dermatology, CICM, Thammasat University , Thailand<br/><br/>Background: Q-switched laser had been introduced for treatment of hyperpigment disorders since 1990. In Asian skin type III to VI, over or under exposure often resulted in poor outcomes or complications. Laser toning with sub-photothermolysis using a 1,064 nm Q-switched laser has been widely practiced in Asia since 2008, but recurrence or depigmentation is common. Since 2019, refractory melasma has been reported to respond well to picosecond 755 nm laser with diffractive lens array (DLA), although recurrence remains an issue. Recently, a new sub-pulsed Q-Switched 1,064 nm laser has been introduced. <br/>Objective: To evaluate the synergistic effect of a new sub-pulsed Q-Switched 1,064 nm laser treatment of refractory melasma in SPT III-V.<br/>Method:Thirteen cases of melasma refractory to picosecond 755 nm laser treatment were treated with a combination of picosecond 755 nm laser with DLA ( 6 mm, 0.8 J/cm2 x 1-2 pass) and sub-pulsed 1,064 nm nanosecond laser 3.56 J/cm2 (2,800 mJ/ pulse, 5 passes ) to hyperpigmented areas at monthly interval for 3 sessions. Melasma Severity Index (MSI) scores using VISIA photography were obtained to assess pre and post treatment results after three monthly sessions. <br/>Result: The new sub-pulsed Q-switched 1,064 nm laser enhanced the effectiveness of the picosecond 755 nm laser, resulting in a 62 % reduction in MSI scores in refractory cases after three monthly treatments. There were 2 cases of treatment failure (15.4%), but no incidence of rebound hyperpigmentation or depigmentation were observed.<br/>Conclusions: The new sub-pulsed Q-switched 1,064 nm laser safely enhances the efficacy of picosecond laser in treating refractory melasma in SPT III-V patients.

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