Tattoo Removal in Darker Skin Types
Tattoos are treated with q-switched lasers of various wavelengths. The most commonly and successfully used laser is the q-switched Nd:YAG. It functions mainly at 1064 nm and 532 nm wavelengths. These wavelengths are absorbed by different colored ink pigments. For instance, black absorbs 1064 best while red absorbs 532 best. Other colors of ink may absorb these wavelengths of laser very little. Other lasers or filters, such as the ruby laser, are better for other colors. The ruby laser functions at 694 nm and is best absorbed by sky blue and green. Other colors, such as yellow, do not absorb any readily available laser light well.
These different wavelengths are also differently absorbed by the natural skin pigment, melanin. 1064 nm is virtually not absorbed by melanin., but 532 nm is most strongly absorbed by melanin. That means that a darker-skinned patient has higher risks of skin-pigment lightening, called hypopigmentation, when the shorter wavelengths of laser are used. A red tattoo is best treated with the 532 nm laser. In a caucasian, if there is mild hypopigmentation that may or may not occur, it will not be noticeable. In a darker-skinned patient, such as African-American, the removal of a red tattoo may leave a mark that is more noticeable than the original tattoo.
The hypopigmentation is not necessarily permanent and often returns to normal, but the risk of a persistent light spot where the tattoo used to be has to be considered. Therefore, when getting tattoos removed with a shorter wavelength laser, such as 532, we inform the patient of the risks of hypopigmentation. For dark-skinned patients, this occasionally factors against getting a tattoo removed.
