Darker Skin a ChallengeTreating a person with dark skin is one of the most challenging tasks for any laser surgeon. This is true for almost any laser and almost any condition a patient may have. The reason this is true is that melanin pigment, which lives in the surface of our skin in our epidermis, is designed to absorb light. Lasers emit light and very often we are aiming at a condition that resides deeper in the skin, below the epidermis. To get there a laser has to go through the epidermis. If there is melanin pigment in the epidermis that melanin pigment will do two things:
- Melanin will steal the light away from what we’re really trying to treat and
- It will make it possible for the laser to injure the epidermis
The laser doesn’t know that the surface of the skin containing melanin pigment is not a target that we’re trying to destroy. So a doctor has to be very careful in choosing the right lasers and the right energies when treating patients with dark skin.
Laser Hair Removal for Darker Skin
For laser hair removal it is extremely important, because hair removal lasers are designed to be absorbed by the melanin pigment in the hair shaft, that we avoid treating the melanin pigment in the surface of the skin. The way to do that is by cooling the surface of the skin to protect it. That can be done with contact cooling, something cold that touches the skin such as two sapphire plates with water running between, or by using a chilled plate, or by a spray that is applied to the skin and cools the skin through evaporation. These are all ways we protect the surface of the skin. The lighter the surface of the skin is, the less chance the laser is going to hurt the skin.
Shorter Laser Wavelengths
If we’re treating patients with very dark skin what we often do is use lasers with the longest wavelength of light. We do this because melanin is designed to absorb short wavelengths of light such as UV Light, and the ability of melanin to absorb light decreases as you go to longer and longer wavelengths, thereby decreasing risk to darker skin. Melanin will still absorb the longer wavelength reasonably well, even at very long wavelengths.
Different Laser for Different Patients
For laser hair removal there are really three types of lasers that we use today, the Alexandrite laser, the Diode laser and the Nd:YAG laser. In the early days of laser hair removal the ruby laser was one of the first lasers that was ever produced, that had the shortest wavelength of all, at 694nm. The Alexandrite laser emits light at 755nm, the diode laser emits light at 810nm, and the Nd:YAG has the longest wavelength at 1064nm. Having someone with different lasers who is highly experienced is a must if you have darker skin.
An Experienced Practitioner is a Must
It requires someone skilled to perform laser surgery because there are a number of variables that one can manipulate when doing laser surgery. The most obvious is the wavelength or the color of the light. When treating very dark skinned patients typically using the 1064nm Nd:YAG laser is the treatment of choice, because that laser is least absorbed by the melanin pigment in the epidermis, but it often still sees the melanin in the hair shaft. One can also manipulate the pulse duration, how long the light stays on, during the laser treatment. For thinker hairs one might often use a longer pulse duration and use a shorter pulse duration for thinner hairs. So treating patients with dark skin or patients who are tan requires more skill and more intimate knowledge of which lasers to use and which settings to use with those lasers. Using the wrong setting or wrong device on dark skin patients has a much higher risk of making blisters or other side-effects.
Last Modified: Febuary 21, 2008
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