Lasers are very special types of light (visible and invisible ‘light’ or energy), but they still emit light.
Melanin pigment in our skin is ‘designed’ to absorb the damaging ultraviolet radiation, UVB and UVA, but also absorbs light through the entire rainbow of visible light all the way to the invisible infrared region at the other end of the spectrum. What does all this science mean to us?
That laser light/energy is absorbed by the melanin pigment in our skin. Lasers can ‘confuse’ the melanin pigment in our skin for the enemy. We are trying to target tattoo pigments in the deeper layer, the dermis, of our skin; but to get there, the light has to pass through our epidermis where our melanin pigment lives. This means that certain types of lasers are more potentially dangerous to darker skin types.
The longer the wavelength we use with a tattoo-removing laser, the generally safer it will be for darker skin types. Of course, this depends upon the wavelength we use, the fluence or amount of energy delivered and the pulse-duration of the laser.
The take-home message is that with skin of color it is often advisable, especially when treating black tattoos, to begin treatment with an Nd:YAG laser that has a wavelength of 1,064 nm-the longest of the Q-switched or picoseond lasers. This wavelength is the least strongly absorbed by overlying melanin pigment, while still targeting the black tattoo ink quite well.
Also, sun-protection is imperative when treating tattoos.
In my office, this means applying a bandage over the tattoo 24/7 while in the sun. Patients come in and tell me “I put sunscreen on it every day” and my response is to “talk to the laser”. Lasers are non-judgmental and can burn tanned skin no matter how much sunscreen one applies when they are away. Waiting until the skin is lighter, or applying creams to lighten the skin are great options in this situation.