Skin reflectance-guided laser selections for treatment of decorative tattoos

A fundamental idea of laser treatment of tattoos is that the wavelength must be well absorbed by the tattoo color. In this study, absorption by different tattoo colors was therefore measured in vivo by skin reflectance to establish optimal laser wavelengths for different tattoo colors. Spectral reflectance by tattooed skin and by normal, uninvolved skin was measured in 10-nm steps in a wavelength range from 300 to 800 nm on eight human volunteers with a total of 13 tattoos, which consisted of 14 different tattoo colors. Wavelength ranges for maximal absorption were established.

We found that tattoos absorbed maximally in the following ranges: red tattoos, from 505 to 560 nm (green spectrum); green tattoos, from 630 to 730 nm (red spectrum); and a blue-green tattoo, in two ranges from 400 to 450 nm and from 505 to 560 nm (blue-purple and green spectrums, respectively). Yellow tattoos absorbed maximally from 450 to 510 nm (blue-green spectrum), purple tattoos-absorbed maximally from 550 to 640 nm (green-yellow-orange-red spectrum), blue tattoos absorbed maximally from 620 to 730 nm (red spectrum), and orange tattoos absorbed maximally from 500 to 525 nm (green spectrum). Black and gray absorbed broadly in the visible spectrum, but these colors were most effective from 600 to 800 nm. Optimal and suboptimal laser wavelengths are proposed.

We recommend that wavelength ranges should be established for maximal tattoo absorption before laser treatment of decorative tattoos to select the most optimal laser wavelength present.