P253 : Comparison of responses to picosecond and nanosecond lasers in the treatment of hyperpigmented skin lesions

Background: In the field of the treatment of pigmentary lesion, the picosecond 755 Кalexandrite laser has been recently introduced, hoping for a better effect on tattoo removal and pigmentation disorders. Objectives: This study compared the efficacy of the picosecond based alexandrite laser (750 Э, 755 К) with nanosecond based conventional Q-switched Nd:YAG lasers (10 Ю, 532 and/or 1064 К) lasers in the treatment of both epidermal pigmented and multi-colored dermal tattoo lesions. Methods: KIWA:A1 guinea pigs with epidermal hyperpigmentation induced by UVB irradiation were treated with each of 755 Кpicosecond laser or 532 КQs-Nd:YAG laser. 6 different color tattoos (red, orange, yellow, green, blue, and black) on the back of albino guinea pigs were treated with one session of 755 К picosecond, 1064 Кor 532 КNd:YAG laser treatment. Results: Although both picosecond and Nd:YAG lasers showed the same effect on epidermal hyperpigmentation, the Nd:YAG laser had more initial tissue reaction and latterly developed post-inflammatory hyperpigmentation. The picosecond laser was superior for removing blue and green color tattoos only, whereas it was inferior or similar for other colors. Conclusion: Picosecond laser is better than conventional Qs-Nd:YAG laser in the treatment of epidermal pigmented lesions, because of no damage to surrounding tissue. However, this device may be less effective in the treatment of color tattoo lesions.