Comparison of the Q-switched alexandrite, ND : YAG, and ruby lasers in treating blue-black tattoos

BACKGROUND. A new generation of highly selective short-pulsed lasers has em erged in recent years for the treatment of tattoos. Several studies (includ ing reports by the present investigators) have proven the efficacy of each of the three commercially available, FDA approved devices; namely, the Q-sw itched alexandrite, Q-switched Nd:YAG and Q-switched ruby lasers. Considera ble differences among the three have been reported in relation to the rate of clearing of the tattoo ink particles, tissue effects, beam profile, woun d healing, and side effects. OBJECTIVE. This study was primarily conducted to examine and compare the cl inical response of patients with blue-black tattoos simultaneously treated with three different Q-switched lasers (alexandrite, Nd:YAG, ruby) with a f ocus on the percentage of tattoo lightening/clearance and the occurrence or non-occurrence of pigmentary change as a side effect. METHODS. A total of forty-two blue-black tattoos seen at two laser centers (Massachusetts General Hospital Dermatology Laser Center and Laser and Skin Surgery Center of La Jolla) were simultaneously treated with three types o f Q-switched lasers: a Candela Q-switched alexandrite laser (755nm 50-100 n anoseconds, 3.0mm spot size, 6-8 J/cm(2)); a Continuum Biomedical Q-switche d Nd:YAG laser (1064nm, 10-20 nanoseconds, 3.0mm spot size, 5-10 J/cm(2)); and a Spectrum Q-switched ruby laser (694nm, 25-40 nanoseconds, 5.0mm spot size, 4-10 J/cm2). Paired t-tests and McNemar tests were used to compare th e treatment outcome and pigmentation side effects between sites per tattoo, with each site representative of one of the three lasers. The statistical significance level was set at p < .05. RESULTS. Overall, the Q-switched ruby laser had a significant difference in tattoo lightening versus the Q-switched Nd:YAG and Q-switched alexandrite lasers. An increase in the number of treatments paralleled a statistically significant increase in tattoo clearance for all three Q-switched lasers. CONCLUSION. The Q-switched ruby laser had the highest clearance rate in blu e-black tattoos and the highest incidence of long-lasting hypopigmentation. The Nd:YAG had no incidence of hypopigmentation.