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/cm2 with a 25-msec pulse duration, 60 J/cm2 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/cm2 and 50 msec and 80 J/cm2 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/cm2) 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/cm2) and longer pulse duration (50 msec) settings were generally correlated with reduced hair counts and improved clinical outcome.