Evaluation of a long-pulsed Nd:YAG laser at different parameters:: An analysis of both fluence and pulse duration

BACKGROUND. Effective hair removal continues to pose a challenge to the physician. The use of lasers represents a significant advance in epilation, but still requires further refinement. The long-pulsed Nd:YAG laser may offer advantages over other systems because of its significant depth of penetration and minimal absorption by epidermal melanin, but ideal parameters need to be determined. OBJECTIVE. To evaluate the efficacy of a long-pulsed Nd:YAG laser system and determine the optimal parameters for hair removal. METHODS. Twenty-two subjects were treated with a cryogen spray-cooled long-pulsed Nd:YAG laser. Four adjacent sites were assigned to each subject, where the following sets of parameters were utilized: 50 J/cm(2) with a 25-msec pulse duration, 60 J/cm(2) with a 50-msec pulse duration, 80 J/cm2 with a 50-msec pulse duration, and control. Hair counts were obtained immediately, 1 week, 1 month, and 3 months after treatment, and multivariate regression analysis was used to determine the significance of hair reduction. Acute reactions and adverse events were also evaluated. RESULTS. Treatment at all three sets of parameters resulted in significant mean hair reductions immediately, at 1 week, and at 1 month (P <.001). At 3 months, the higher settings of 60 J/cm(2) and 50 msec and 80 J/cm(2) and 50 msec were statistically significant for reduced mean hair counts (P =.014, P =.042, respectively), while the lowest setting at 50 J/cm2 and 25 msec was not significant (P =.079). Patient and physician assessments suggested optimal hair reduction at the highest fluence (80 J/cm(2)) and longest pulse duration (50 msec). The most common acute reactions were pain during treatment, erythema, and perifollicular edema, all of which were more severe with higher fluences. CONCLUSION. The long-pulsed Nd:YAG laser is a safe and effective method of hair removal. Increased fluence (60-80 J/cm(2)) and longer pulse duration (50 msec) settings were generally correlated with reduced hair counts and improved clinical outcome.