Laser assisted hair removal for darker skin types
Before the advent of new safety procedures, laser hair removal
had not been an option for people with darker skin. People with
lighter skin types of I-III on the Fitzpatrick scale of skin color
had been the only individuals that could safely benefit from laser
treatment. Laser hair removal was often not an option for people
with darker skin color as the lasers could damage pigmented skin.
In laser hair removal, energy from the laser light is absorbed
into pigmented cells. Those cells with more pibment absorb more
energy. The energy damages the cells, usually through heat buildup
which “cooks” the cells. This is good if you want
to remove hair follicles, but bad if the skin around the hair
follicles is also highly pigmented. Recently, however, there have
been three advances in science which have made it possible for
people with darker skin types to undergo laser treatment. Those
advancements include the use of longer light wavelength lasers,
the longer pulsed laser and more efficient skin cooling devices.
With these advancements, patents with darker skin types IV-VI
are now able to enjoy the benefits of laser assisted hair removal.
Scientists have recently improved the use of lasers by finding
a way to focus the light beam on the hair shaft and bulb where
the melanin is most rich and minimize the exposure of the surrounding
skin to the laser energy. This is done by first determining the
amount of time it takes for the hair shaft to achieve “thermal
relaxation”. Thermal relaxation is a technical term that
means “the time it takes for 50% of heat energy to be conducted
away from a target tissue”. Once this thermal relaxation
time is determined, scientists adjust the pulse duration of the
laser to that same thermal relaxation time in the hair follicles.
This time is usually found to be about 10 to 100 milliseconds
in duration. The optimal laser pulse duration should be longer
than the thermal relaxation time of the epidermis, allowing heat
energy to be conducted away from the skin, but shorter than the
thermal relaxation time of the hair follicle This confines the
laser induced heating to the hair follicles structure. In other
words, the heat induced by the laser builds up in the hair follicles
because it cannot escape quickly enough, but it does not build
up in the skin around the follicles as the heat can dissipate
In order that the hair follicle be completely destroyed, the
tissue immediately surrounding the hair follicle must also be
diffused with heat. This surrounding tissue is the place where
the stem cells for future hair follicles reside. The locations
of stem cells exist in both the distal and proximal outer root
sheaths of the hair follicle. These are located at the base of
the hair follicle deep inside the skin. To reach these areas with
the laser requires an even longer laser light pulse duration than
is normally required. If the skin is darker, the melanin inhibits
the light beam from reaching its eventual target at the base of
the hair follicle. Instead, the light is converted into heat by
the melanin and can cause a dangerous blister at the surface of
the skin. With longer wavelengths, longer laser pulse durations
and better cooling procedures, this problem can now be alleviated.
The cooling procedures on the skin have been improved in numerous
ways. First, the longer pulse durations send the heat into the
skin at a much slower pace. This allows the skin to naturally
cool as the process is taking place. Inherent cooling devices
such as direct contact of a cooling plate or cooled spray also
added to the safety of the process.
There were two laser wavelengths that were found to be best
for darker skin types. These were the diode (810 nm) wavelength
and the Nd:YAG (1064 nm) wavelength. The diode wavelength was
the shorter wavelength and also the most effective. The 1064 nm
wavelength was longer but safer for darker skin types. In order
to make the longer wavelength more effective for hair removal,
shorter pulse durations could also be used with the Nd:YAG wavelength
along with adjunct cooling methods in order to treat the darkest,
and most sensitive Fitzpatrick skin type VI. The lasers, Nd:YAG
and the diode, are both approved by the Food and Drug Administration
and are now widely used in many clinics.
To determine the correct settings for the laser, the skin is
evaluated at specific areas or "test spots" before starting
the actual hair removal procedure. These spots are usually in
the same area as where the treatment is going to take place. Of
course, high profile parts of the skin, such as the face, have
to be avoided in case there is an undesireable side effect. Also,
the safest parameters, low fluence and longer pulse durations,
are tested first in order to avoid any serious damage on the skin.
The the settings on the laser a gradually increased until the
desired effect is produced with minimal side effects. Special
care is taken in areas with heavy amounts of hair because the
heat often pools in those areas and can create damaging effects.
After four tests and a 48 hour waiting period, technicians observe
the skin for any serious damage.
In terms of the immediate test results and the determination
of the correct fluence, laser technicians should look for several
indicators. First, they would ask the patient if there had been
any pain or discomfort. If there had been any pain, the fluence
would be lowered. A topical anasthesia can also used if the patients
experienced significant pain. Secondly, technicians would look
to see if the treatment was even mildly successful in treating
the unwanted hair. A mild response to the hair is known as "perifollicular
erythema" and is a good indicator that the correct fluence
has been obtained. Erythema involves a temporary reddening of
the skin around the hair follicles in response to the thermal
damage caused by the laser. A prolonged presence of perifollicular
erythema would indicate that the fluence had been too high.
There had pareviously been certain medications and pre-existing
conditions in the skin that had been considered unsafe to patients
using laser treatment. These determinations, however, have been
found to be mostly innacurate or unfounded. Photosensitizing drugs
that had been activated by ultraviolet "A" wavelength
light had been considered unsafe to some degree but the advent
of newer lasers was now making this danger a thing of the past.
Similarly, patients with a history of keloids or hypertrophic
scarring were considered to be at higher risk of side effects
from laser treatments. Newer lasers, however, also make this danger
mostly irrelevant. Patients who had taken accutane were also considered
to be at risk ofr side effects with laser hair removal, but the
studies making claims about accutane are also unfounded. The only
clear danger that scientists have determined involves patients
who have experienced chronic or active herpes infections prior
to their laser treatment. This is especially true if the infections
existed in the proposed treatment area of the skin. To counter
this danger, patients can be treated with antiviral drugsone day
before the treatment and treatment continues for five to seven
days after the laser treatment session.
Once laser treatment has been decided upon, there are certain
preliminaries that must take place to prepare the skin. The patient’s
skin must first be thoroughly cleaned and shaved. Any topical
anesthetic that had been used should be removed and an alchohol
cleansing should be performed at the location where the laser
will be applied. The alchohol should be wiped away with water
and the doctors and everyone present should put on protective
goggles to avoid any damage to the eyes from the laser light.
Besides the already mentioned areas of the skin that have very
dense hair, there are other areas that demand special attention
so as to avoid any skin damage during laser treatment. The neck
on female patients is especially prone to scarring and should
therefore be treated with a lower laser fluence. The face is also
a very sensitive area that should demand special care. It is especially
crucial to thoroughly shave the upper lip prior to the treatment
to avoid any damage to the skin.
It is considered to be very important that patients understand
the laser treatment and its likely effects prior to receiving
the treatment. There is usually some level of discomfort in the
treatment that each patient should be informed about. Doctors
should inform the patients that they will need multiple treatments
to completely remove the unwanted hair. This is especially true
for patients with darker skin types. Patients are also told not
to use waxing or plucking of their hair follicles during the treatments.
Shaving, however, and the use of depilatory creams is acceptable.
Laser treatment has become a great option for many special cases
that were previously untreatable with conventional methods. Patients
who used to experience folliculitis due to lasers and laser settings
inappropriate for their skin type are now being treated with more
refined and successful methods. Pseudofolliculitus is another
condition which causes ingrown hairs around the beard and underarms
which is now treatable with laser technology. Finally, Acne keloidalis
nuchae, which plagues many African-Americans, is now successfully
treatable with laser technology. Thanks to the newest discoveries
in laser treatment, people with darker skin types will now enjoy
all the benefits that those lighter skin types have enjoyed in
the past from laser hair removal.
Laser assisted hair removal for darker skin types references
- Battle EF Jr, Hobbs LM.
Laser-assisted hair removal for darker skin types. Dermatol
Ther. 2004 Jun;17(2):177-83. Review.