Laser hair removal was first approved by the FDA in 1995 and since then it has been steadily gaining popularity with the masses as the news of its effectiveness in providing long-lasting hairlessness spreads.
It is the most commonly opted non-surgical cosmetic procedure popular with the audience ages 18 years and younger.
Relying on some solid facts and figures, it was mentioned that in 2005, 1. 5 million laser hair removal procedures were performed which is an increase of 300% since the year 2000.
Although, it has been widely mentioned that the treatment is most suitable for light skinned and dark haired individuals, the following sections of the article elaborate on what the treatment is and how it can be tweaked to work effectively for ethnic skins as well.
What is Laser Hair Removal?
Laser hair removal can be mentioned as a relatively permanent solution for hair removal as compared to the other alternatives available.
The procedure makes use of laser light to target the hair and prevent or prolong its regrowth.
There are various kinds of laser treatments available that differ from each other in the kind of laser used, i.e. Alexandrite, Nd:YAG, Intense Pulsed Light or diode lasers.
All of these operate on different wavelengths and make use of specialized machines to do so.
Different skin types are suited to different procedures and hence, it is important to consult a dermatologist before going for these procedures.
There are a lot of other factors that need to be taken into consideration too, like the area to be treated, the hair color and skin color, the hair thickness or coarseness and density, the rate of hair growth and many other things.
All of these vary with individuals and therefore, proper professional consultation is necessary for this procedure.
How does laser hair removal work? How is skin color a factor in this process?
For us to understand the implications of using the laser on dark-skinned individuals, we need to first understand how does the laser interact with the hair and the mechanism behind the procedure.
The main mechanism behind laser hair removal is selective photothermolysis.
This concept allows the transfer of heat energy from the laser to the hair follicle to destroy it without any damage to the surrounding cells.
The main target of the laser light is the component melanin that is present in the follicles.
The absorption spectra for melanin are very broad ranging from ultraviolet (400nm) to infrared (1200nm).
In theory, any of these wavelengths can be used to destroy melanin, however, it is said that shorter wavelengths are more effective.
This component is present in the bulge of the follicle and therefore, the wavelength should be selected so that it can penetrate deep enough as is required and also not cause any damage to the surrounding skin cells.
Also, the other factor to be taken into consideration is how much energy should be delivered and the procedure will be effective only if the absorption is suitable enough to cause damage in a time period less than the thermal relaxation time (thermal relaxation is the time lapse between two consecutive pulses as the skin needs to cool down between successive thermal agitations to avoid permanent damage to the epithelial cells).
So, now the question arises that how does a skin’s color affect the effectiveness of the treatment?
The darker or more tanned skin has a higher melanin distribution in the epidermis (skin) as compared to white, non-tanned individuals.
As melanin is the focus of the laser light, the ethnic skin is at a higher risk of skin damage as compared to its fair-skinned counterparts.
It also takes a significantly longer thermal relaxation time as compared to lighter skin (100 microseconds for a white individual as compared to 25 milliseconds for the tanned one).
Pulse duration is the amount of time the laser energy is delivered to the hair follicle and thicker hair require longer pulse duration.
For the darker skin type, longer pulse duration implies more fluence is delivered.
Fluence is the amount of energy transferred in the form of heat. The goal is to deliver the highest fluence possible without epidermal injury.
How skin color affects the laser hair removal method?
As has been mentioned above, darker skin has more melanin content that is uniformly distributed across the skin.
As melanin is the main target of laser light, this puts the dark-skinned individuals at a higher risk of skin damage and other side effects.
There is a scale called the Fitzpatrick scale that categorizes the different types of skins.
It is advised, that before treating a skin type of V or VI, the dermatologist should have a sound knowledge of the laser hair removal treatment methodologies as well as a list of cooling devices and techniques handy because the skin heated up quickly and takes more time to cool as compared to the lighter skinned individuals.
One can understand how the skin color affects the treatment by looking at the different kinds of problems faced by ethnic skins on interacting with laser light:
- A darker skin usually means high melanin content in the epidermal cells. As melanin is a competent chromophore (meaning that it is a very fast absorber of the laser light), there is a chance of blistering, crusting and scar formation. Complications like dyspigmentation are also common.
- Melanosomes which contain melanin are bigger in size in the darker individual and spread throughout the stratum of the skin. They are uniformly distributed throughout (individually dispersed) and also have higher melanin content as compared to the smaller melanosomes in the white, non-tanned individuals. These melanosomes end up absorbing more light which was intended for the hair follicles thus, causing more harm than good.
- Also, a majority of black patients have spiral hair and curved hair follicles which lead to a serious condition wherein the newer hair grows in a curled manner into the skin which can cause irritation.
- The total hair density and the number of hair follicles is significantly lower in African Americans as compared to white people and this is an important observation because more dense follicles means more thermal absorption and therefore, a greater risk for side effects.
All these observations are factored in when trying to come up with a safer hair removal procedure for darker skinned individuals.
Each of these observations about the skin types affects the kind of treatment that needs to be undertaken to reduce the risks and maximize the results.
What are the side effects that dark-skinned individuals face?
Although laser hair removal is generally considered safe, there are certain risks as is the case with all other procedures as well. Erythema (redness of the skin), edema (swelling) , vesiculation (blistering), hypopigmentation (loss of skin color), hyperpigmentation (darkening of the skin), growth of thinner or paler hair, induction of hair growth, and scar formation are the common side effects.
The darker individuals are more susceptible to these side effects.
They are at a higher risk because of the distribution and content of melanin in the skin due to which the laser light which is intended for the hair follicles ends up being absorbed by the skin.
What are the ideal laser treatments for the darker skin?
To come up with some sort of plausible solution to this problem, we analyzed a series of research studies to find out. These are listed as follows:
Sixteen patients with skin type IV were treated with the ruby laser for a long pulse duration of 20ms and fluence of 15-20 J/cm2.
Even then, the patients developed post treatment hyperpigmentation. Although, this was eventually resolved, it still implied a greater risk for individuals with skin types V and VI.
Liew et al.
The study was conducted with 24 patients with type V skin with a pulse width of 500 μs and a fluence of 13.1 J/cm2. 8% cases reported blistering, hypopigmentation and hyperpigmentation.
15 patients were treated with a 3 ms pulse duration, at a mean fluence of 10.5 J/cm2. 37.8% experienced side effects including blistering and crusting as well as hypopigmentation, hyperpigmentation, and purpura.
In 150 dark-skinned patients (skin types IV–VI, 70 of which were types V and VI) treated with the alexandrite laser (18 J/cm2, 40 ms), side effects occurred in about 3% of cases and included blistering, folliculitis, transient hyperpigmentation, and transient hypopigmentation.
Galadari et al.
Galadari evaluated 100 patients with types IV–VI skin using a pulse duration of 40 ms and a fluence of 20–40 J/cm2.21 Side effects included redness, superficial burn, scarring, hyperpigmentation, and hypopigmentation. Superficial burns occurred in 60%, pigmentary alteration in 48%, and scarring in 15% of patients.
Greppi treated 8 patients with an 810 nm diode laser with a 30 ms pulse duration and a fluence of 10 J/cm2.22 Two patients experienced blistering, crusting and hypopigmentation, while 3 experienced hyperpigmentation.
They treated patients with type V and VI skin with 30 ms pulse duration and fluences ranging from 30–60 J/cm2.24 Only transient hyperpigmentation was observed in 1% of the patients.
Conclusions from the Studies
It can be seen from all the above-mentioned studies that darker skinned individuals require a higher fluence level and this means more energy is supplied to the skin than it is supplied for lighter skinned and darker hair people.
When more heat is applied, the procedure may seem painful and uncomfortable; however, damage to the skin can be minimized by the application of cooling techniques.
There is no special treatment method that will work best for darker skin tones.
It varies from one individual to the next; however, it is important that all of the treatments are followed by a proper cooling of the treated skin.
It is only due to the advancements in cooling techniques that one has been able to make laser treatment possible for the darker skinned individuals.
The following section is a brief discussion of the cooling principles applied and the devices used.
Discussion Regarding Cooling
It is a common observation that when the laser light hits the follicle, there is also related heating of the surrounding skin cells.
It is important that the heating does not exceed the threshold temperature and therefore, cooling is important to avoid epidermal injury.
There are many cooling devices available but their important goal is to cool the basal layer of the skin which is the most heavily pigmented and therefore, more susceptible to damage.
These devices can be categorized as contact and non-contact cooling devices.
- Direct contact allows the application of pressure to the skin which blanches the blood vessels and therefore, minimizes the absorption of the laser by the hemoglobin. An example is the sapphire tip which acts as a heat sink because of its high heat conductivity as compared to the skin.
- Cryogen spray cooling or dynamic cooling is the most common non-contact cooling method. Tetrafluoroethane is the material used in this method which has been approved by the FDA. It is sprayed onto the skin surface before the pulse comes in contact. Forced air cooling is another method of this type although it is much less effective as the air cooled at -30 degree Celsius needs to be blown for a prolonged time for cooling the basal layer.
New technology combined the IPL with radio frequencies so that less optical energy is used which makes it safer for the darker skinned individuals. The radiofrequency energy is delivered via bipolar electrodes to the skin.
The current generated penetrates deep into the hair follicles causing the necessary damage and the skin cells conduct the lowest current which means very less heat is generated in the skin.
Although the laser hair removal procedure has many takers, its effectiveness has been proved time and again for the lighter skinned individuals while that is not the case for the tanned skins.
However, longer pulsed durations with parallel cooling devices have allowed this procedure to be performed fairly safely and quickly.
One can rely on the ongoing research to develop a technology that relies less on pigmentation and is, therefore, safer for the ethnic skin.
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