The Effect of a Frequency-Doubled Q-Switched Nd:YAG Laser on Hairless Mice Harboring Eumelanin and Pheomelanin in the Epidermis

Background: For laser therapy, darker skin types should be carefully treated, however, the precise role of melanin content, subspecies, and the heat effect of the laser has not been well studied in vivo. Methods: We generated three groups of mice that have epidermal melanocytes producing only eumelanin, dominant pheomelanin, and no melanin. Using these mice, the effect of a frequency-doubled Nd:YAG laser was studied. Results: The mouse epidermis that contained eumelanin underwent heat degeneration at a lower fluence when compared with the mouse epidermis with dominant pheomelanin. The mouse skin with no melanin did not show any degeneration of the epidermis. Conclusion: The effect of the Nd:YAG laser on the cells containing different melanin subspecies was shown to be different in an in vivo irradiation system.