Hair structures are effectively altered during 810 nm diode laser hair epilation at low fluences

Abstract

Diode lasers with high fluence and cooling technology are effective at removing unwanted hair but are also associated with discomfort and morbidity, especially when treating dark or tanned skins.
Thirty patients with skin phototypes IV and V (range: 23-62 years of age; average: 39 years) underwent a single hair removal treatment using a new diode laser (810 nm) technology that incorporates low fluence but very high average power. The treatment technique employed multiple, in-motion, repetitive laser passes on a 100 cm(2) area of the skin. A 5mm punch biopsy was carried out before and after a single treatment. Tissue samples were harvested and stained with haematoxylin-eosin.
The physical integrity of hair follicles was altered with inflammatory infiltrate, hair shaft detachment from its sheath, and perifollicular oedema, related to incipient necrosis.
Low fluence but high average power diode laser technology yields significant changes in hair structure and architecture in patients with dark skin types. The procedure caused low levels of discomfort and was well tolerated.

Full text

Journal of Dermatological Treatment. 2009; 20:4; 1–4
ISSN 0954-6634 print/ISSN 1471-1753 online © 2009 Informa UK Ltd.
DOI: 10.1080/09546630903085286
SHORT REPORT
Hair structures are effectively altered during 810 nm diode laser hair
epilation at low uences
MARIO A. TRELLES1, FERNÁNDO URDIALES2 & MARWAN AL-ZAROUNI1
1Vilafortuny Medical Centre, Dubai, UAE, 2Instituto Médico Miramar, Malaga, Spain
Abstract
Background: Diode lasers with high uence and cooling technology are effective at removing unwanted hair but are also asso-
ciated with discomfort and morbidity, especially when treating dark or tanned skins. Methods: Thirty patients with skin photo-
types IV and V (range: 23–62 years of age; average: 39 years) underwent a single hair removal treatment using a new diode
laser (810 nm) technology that incorporates low uence but very high average power. The treatment technique employed
multiple, in-motion, repetitive laser passes on a 100 cm2 area of the skin. A 5 mm punch biopsy was carried out before and
after a single treatment. Tissue samples were harvested and stained with haematoxylin-eosin. Results: The physical integrity of
hair follicles was altered with inammatory inltrate, hair shaft detachment from its sheath, and perifollicular oedema, related
to incipient necrosis. Conclusion: Low uence but high average power diode laser technology yields signicant changes in hair
structure and architecture in patients with dark skin types. The procedure caused low levels of discomfort and was well tolerated.
Key words: Fluences, hair removal, histology, laser, melanin
Introduction
Photo-epilation was the most practised medical
intervention in 2008 (1). Unwanted hair causes psy-
chological distress due to ‘imposed’ social rules. Several
techniques that use different light devices can be used
to remove hair, but there are limitations when treating
dark or tanned skins.
When laser epilation is carried out on light skin and
dark hair, the rate of success is high (2). The selective
absorption of laser light by the hair follicle in the
810–1200 nm spectrum band is expected to cause
thermal damage to the hair follicle growth centres–
bulge, bulb and papilla. Reports based on histology
observations present extensive immediate damage of
hair follicles after laser treatment (0–8). Reports on low
uence epilation with IPL devices (9), lterless ash-
lamp systems (10), and the alexandrite laser (11)
produce partial degeneration of hair follicles and
changes such as coagulation in the standard pattern of
the neighbouring tissue. Thus, there is a need for an
improved method for hair removal which heats the hair
follicles to a sufcient temperature for hair removal
while delivering a minimal amount of thermal energy
to the epidermis (to achieve minimal discomfort).
A new 810 nm diode laser device for hair removal
may have clinical advantages for epilation on dark
and/or tanned skins due to its very high average
power, high repetition rate, albeit at low a uence,
and may be a safer procedure that offers the possibility
of achieving high clearance rates of hair removal with
low morbidity. In order to evaluate the extent of
treatment effects at the level of the hair follicle and
to assess the extension of these effects in tissue, we have
examined the histology of epilated areas in 30 patients
immediately after a single treatment session.
Materials and methods
Patients with phototypes IV and V (15 males and
15 females in each group), ranging from 23 to 62 years
Correspondence: Mario A. Trelles, Instituto Medico Vilafortuny / ANTONI DE GIMBERNAT FOUNDATION, Av. Vilafortuny, 31, E-43850, Cambrils,
Spain. Fax: 34 977 791024. E-mail: imv@laser-spain.com
(Recevied 10 March 2009; accepted 18 May 2009)
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2 M. A. Trelles et al.
temperature never exceeded 42ºC. Presumably, due to
the high average power and depth of penetration of the
810 nm diode, the tissue temperature in the dermis
was higher, as well as at the level of the hair follicle, due
to its signicant higher density in melanin content
acting as a chromophore conductor for the 810 nm laser
emission. Once patients felt minor pain and/or a heat
sensation (12), the hand-piece was moved to the
neighbouring area, continuing the epilation procedure.
Once total uence was achieved in the whole area
of treatment, a 5 mm punch biopsy was carried out
in the same manner as it was performed prior to the
start of treatment. A local injection of 0.5 ml of lidocaine,
without vasoconstrictor, was administered. Samples
were processed and stained with haematoxylin-eosin
and were examined by an independent pathologist,
who was requested to comparatively evaluate the
changes occurring before and after treatment.
Results
The post-treatment epidermis was of normal
conguration, and the keratin layer was intact with
no identiable changes. The samples of seven patients
had some epidermal–dermal junction contraction,
represented by more noticeable papillary crests in the
dermis together with cytopathic and vacuole changes
at the keratinocyte level (Figure 1). Moderate oedema,
particularly in the dermis, was visible in its supercial
layer. The dermis appeared normal and viable. Hair
shafts detached from hair sheaths with perifollicular
oedema, related to incipient necrosis, clearly visible
due to the darker colour of the staining. There were
variations in the standard physical integrity of hair fol-
licles with inammatory inltration. None of these
changes were present in the pre-treatment samples
(Figures 2 and 3). Perifollicular oedema was clearly
visible in all samples, together with signs of haemorrhage
between the collagen bres located at stroma level,
representing a trauma which could be responsible for
the epilation effect. Low-uence laser epilation caused
anatomical changes in the follicle that compromised
its integrity.
Discussion
Safety and efcacy standards are not well established
for laser hair removal in patients with a dark skin type.
Methods to destroy hair follicles while keeping the
epidermis alive are needed. We found that an 810 nm
diode laser delivering a very high average power at a
low uence altered hair structure. While the changes were
not dramatic, clinically there were fewer and ner
hairs in the treated areas. Patients reported delayed
regrowth at follow-up 1 month after treatment. A
of age (average 39 years), were enrolled. No patient
had undergone any previous photo-epilation and all
had dark, thick hair that they regularly epilated using
either electric or blade razors.
The study was approved by the Ethics Committees
of the Antoni de Gimbernat Foundation.
Patients underwent a single hair removal treatment
with the 810 nm Soprano® XL diode laser device
(Alma Lasers, Caesarea, Israel). The nozzle of the laser
hand-piece incorporates Sapphire Dual Chill Window
Technology through which a coolant is in constant
circulation. Also, the hand-piece has an adapter to
connect a cold air tube that focuses directly where
the nozzle is pointed and continuously cools the area
of treatment. The window from which the laser emits
is 12 × 10 mm in size. The cooling system (Cryo 5;
Zimmer ElektroMedizin, Neu-Ulm, Germany) was set
to operate at intensity level #5 (high ow of cold air).
The diode laser pulses at a xed rate of 10 Hz
and at uences varying from 5 to 10 J/cm2. Lower
uences can be used in darker skin types; 8 J/cm2 was
used in this study. The pulse width adapts according
to selected uences, and ranges from 10 ms for 5 J/cm2
to 20 ms for 10 J/cm2. The treatment technique
involves moving the hand-piece in a sweeping con-
stant movement. The skin surface for treatment was
divided into 10 × 10 cm squares and each received
a total of 8 kJ. Thus, each 1 cm2 of skin received on
average 80 J/cm2 (8000 J/100 cm2 = 80 J/cm2). The
reason for dividing the treatment area into 100 cm2
areas was to provide homogenous treatment exposure
and to carry out systematic epilation. The hand-piece
was moved over the skin at a speed of approximately
10 cm per second.
Areas of epilation were four side burns, 12 axillae,
four bikini lines, six legs and four arms. Treatment
areas were shaved and thoroughly cleansed with soap
and water. Then, a thin coat of gel at an ambient
temperature was applied to the skin surface for the
purpose of facilitating the sliding of the laser nozzle
over the skin at the time of treatment. During treat-
ment, tissue temperature progressively increased. The
end point for stopping laser passes was when intense
erythema, pain or a burning sensation was present or
when an accumulative energy of 8 kJ was attained.
Patients were told to expect a heat sensation and were
asked to advise the therapist when they felt unbearable
pain or an intolerable heat sensation. The purpose of
the treatment was not to burn the skin but only to reach
levels of tolerable pain or intolerable heat sensation.
In order to have a reference of the temperature achieved,
skin temperature was measured during treatment with
an infra-red (IR) surface thermometer (IR Surface
Thermometer A28886; Zenit Measuring/Testing
Instruments™, USA). At the time of treatment, the
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Laser epilation, using low uences 3
Figure 1. Skin × 125 H&E. Cytopathic and vacuole changes at the
keratinocyte level are clearly seen.
Figure 2. Skin × 400 H&E. Perifollicular oedema and peribulb
thermal damage, represented by darker staining, and polymorphic
nuclear cell inammatory inltration are noticed respecting the
integrity of the neighbouring tissue.
Figure 3. Skin × 250 H&E. Images of haemorrhaging are seen in
between the collagen bres at the stroma hair level.
Figure 5. Skin × 400 H&E. Presence of hair disruption with de-
tachment from its shaft. Peri-isthmic brosis is observed together
with inammatory inltration.
Figure 4. Skin × 400 H&E. Perifollicular oedema is clearly noticed as
a consequence of thermal effects.
single session with the low-uence, high pulse rate,
810 nm treatment can produce effective epilation.
Although the uence of each individual pulse
delivered is relatively low, the rapidly delivered pulses
collectively effectively heat the patient’s dermis. Since
the hair follicle is in thermal equilibrium with the
surrounding tissue and it is more sensitive to heat, it
is more prone to thermal damage with repetitive, pro-
longed laser exposure. Thus, once the sub-dermal layer
is signicantly heated and the temperature at the hair
follicle is sufciently high, only a few additional high-rate
pulses of low uence are needed to raise the temperature
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4 M. A. Trelles et al.
of the hair follicle to an effective temperature to impair
the function of its biological elements. More-over,
melanin in the hair follicle acts as a chromophore,
providing a degree of selective heating. Because an
excessive heat gradient may cause pain, once the
sub-dermal layer is sufciently heated, individual
pulses should only provide enough energy to the hair
follicle to achieve a critical temperature to impair the
function of biological elements and hair growth.
Some follicles were damaged in their outer root
sheath, others appeared with lesions of the inner root
sheath, and others were of normal aspect. This may
be attributed to a different volume and degree of heat
in contact with the target, which is translated into
oedema (Figure 4). Also, heat propagation from dermis
to epidermis may be responsible for cytoplasm changes
and vacuole formation at the level of keratinocytes,
as observed in practically all ‘immediately after’
samples (Figure 5).
The 810 nm diode laser causes signicant thermal
damage and histological alterations to the hair follicle
but not to the epidermis, even in patients with dark
skin types. This may have important clinical implications
for the dark-skinned population seeking a safe and
effective hair removal procedure.
Acknowledgements
The author declares no nancial or other interest in the
companies and/or equipment mentioned in this study.
The preliminary conclusions of this study are regis-
tered in the academic activities of the FUNDACION
ANTONI DE GIMBERNAT year 2000–2008.
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