Hair Removal Using a Combination of Electrical and Optical by jizhen1947


									Hair Removal Using a Combination of Electrical and Optical
Energies 3-Month Clinical Study

Antonio Del Giglio M.D., James Shaoul M.D.

                                                              level of safety and efficiency, innovation in the
Introduction                                                  underlying technology is now required.
Light assisted hair removal, or photo-epilation, is a
highly popular medical-cosmetic procedure that is             Study objectives
based on the strong desire to be rid of unwanted hair         The multi-site clinical study was conducted with the
from various parts of the face and body. Conditions           aim of evaluating a new method of hair removal. The
leading to the desire to remove hair can include              main idea behind the method is to decrease optical
hirsutism, congential or drug-related hypertrichosis,         energy to the level that is safe for all skin types, while
pseudofolliculitis, transsexual states, and skin grafts.      compensating for the lack of light by utilizing an
First introduced six years ago1 , and further developed       additional energy that is not optical, but is selectively
in the years since then, light-assisted hair removal has      absorbed by the hair structure. The other key
been proven to provide long-term, sometimes                   requirement for the selected energy was that it not
permanent, results 2,3 .                                      affect the melanin of the epidermis.
Photo-epilation is based on heating of the hair shaft by      The study was conducted with the Syneron Medical
selective absorption of optical energy. There are two         Aurora DS hair removal system, which utilizes a
kinds of light sources that provide energy at a high          combination of conducted electrical energy in radio-
enough level to achieve thermal destruction of hair:          frequency (RF) range and optical energy. Light pulse
lasers and intense incoherent light. The differences          in the near infrared range was applied simultaneously
between the results obtained with various wavelength          with a pulse of RF energy. Absorbed energy comprised
ranges are not significant. In order to improve               electrical energy and optical energy in approximately
treatment safety, some companies have begun using             equal parts.of Conducted RF energy was applied
wavelengths that are not well absorbed by the melanin         through the electrodes embedded in the system
of the epidermis (for example, Nd:YAG laser                   applicator and brought into contact with the skin
producing      near-infrared   light   at    1064nm) 3 .      surface. The geometry of the electrodes was optimized
Unfortunately, the main absorber in the hair is also          to provide an energy penetration depth of 4mm. In the
melanin, hence the effect of these wavelengths on the         study, higher RF energy and lower optical energy was
hair is limited. To compensate, higher energy fluence         used for dark skin, while for light skin, RF energy
must be applied to the patient to achieve the desired         comprised only 25% of the total fluence.
treatment effect.
The primary challenge of photo-epilation is to deliver        Methods and patients
to the hair root the amount of energy required to             60 male and female patients with Fitzpatrick`s skin
destroy it, without damaging the epidermis that the           type 2 to 5 and various hair colors were selected for the
energy passes through. Both cooling and long pulse            study. Table 1., below, shows the distribution of
duration have a significant effect on treatment results       patients by skin type. The range of ages of the patients
as they decrease heating of the epidermis, thus               was 18-46 years.
allowing the application of higher energy to the skin 4,5 .
However, this methodology is also limited: pulse              Table 1.
duration cannot be increased infinitely, because, if it            Skin Type           Number of patients
exceeds thermal relaxation time, the efficiency of the             2                   11
hair heating is decreased. Furthermore, if cooling is
                                                                   3                   33
applied too intensively, it can cause skin damage.
                                                                   4                   12
Thus, optimization of light-based treatment has now                5                   4
reached the saturation point. In order to achieve a new

A variety of body sites were chosen for the study, as       Immediate results
shown in Table 2., below. The face was the most             In contrast to other purely optical devices, the Aurora
prevalent site treated and studied.                         DS system uses a low level of optical energy, which
                                                            leads to less heating of hair shafts. Hence, hair shaft
Table 2.
                                                            evaporation was not commonly observed.
     Site                  Number of patients
                                                            RF energy mainly affects the hair follicles, causing
     Facial                28                               them to coagulate. Effective cooling protects the
     Bikini Line           2                                epidermis from the immediate perifollicular erythema
     Axilla                5                                and only perifollicular bleaching was observed after
     Legs                  4                                the pulse. Bleaching is a result of perifollicular
     Trunk                 21                               coagulation, which causes the transparency of the
                                                            perifollicular tissue to decrease. In most cases,
                                                            perifollicular edema and erythema were delayed,
Informed consent of all participants was obtained and       appearing after 10 to 15 minutes. While transient
the body sites to be treated were identified and
                                                            erythema was observed in some patients, it disappeared
photographed. A baseline hair count was obtained            within a few hours. As the cooling has the effect of
manually. The target areas were shaved prior to             delaying all side effects, the patients were asked to
treatment. No topical anesthetic cream or other
                                                            observe the treated site and to report any side effects
anesthetic was applied.                                     noticed in the immediate hours or days following the
The Aurora DS system, which employs a combination           treatment.
of optical and conducted RF energy for hair removal,
                                                            The photographs below depict an example of the effect
was used for the study. RF energy was applied to the        on the hair follicle of treatment with light and
skin surface via two electrodes embedded in the             conducted RF energies delivered by the Aurora DS
applicator of the system. The shape and the distance
                                                            hair removal system. No adverse effects to the
between the electrodes are optimized for penetration of     surrounding skin were noted. Under normal, non-
up to 4mm. It is important to note that RF energy           magnified conditions, there were no visible changes to
absorbance does not depend on skin pigmentation, but
                                                            the skin. Only under high magnification were changes
is determined by the electrical parameters of the tissue.   observed.
The frequency of the RF current in the pulse is
optimized to penetrate through the skin surface and to      As seen on the right hand side of Figure 1., the treated
be selectively absorbed by the hair follicle.               area was photographed through a zoom (x80) lens. The
                                                            upper photograph shows the treated area before the
In the study, the light energy range used varied from       pulse, while the lower photograph shows the same area
15 to 28 J/cm2 , while the RF energy range was 10-20
                                                            immediately after the pulse. It is interesting to note the
J/cm3 . Skin temperature was maintained at around 5°        white rings (bleaching) that appear around the hair
Centigrade by the effective epidermal cooling provided      follicles. The picture was taken within a few minutes
by the system.                                              of the pulse being applied. The left side of Figure 1.
                                                            shows the entire treated area through a standard camera
Treatment procedure and results                             lens before and after treatment.
Treatment technique                                         Follow-up observation
In the study, transparent gel and water was used for        During the first week after the treatment, no significant
skin hydration. Light pressure was applied via the          hair reduction was observed, which was the expected
applicator to the treatment sites in order to ensure good   response, due to the time it takes for the hair to fall out
coupling of electrodes to the skin surface. Treatment       of the follicle. Maximum reduction in hair was
overlap of up to 20% was acceptable.                        observed at 2 weeks to 2 months after a single
On patients and/or body sites with darker skin, lower       treatment.
optical energy was used, while higher optical energy        The study patients were observed 3 months after the
was used on patients and/or body sites with lighter         treatment. A clinical examination and hair count were
skin. Light hair absorbs less optical energy than does      employed to access the efficacy of the treatment.
dark hair, while RF energy is equally efficient for all     Clearance (see Table 3., below) was calculated as the
hair colors. Thus, the use of higher RF energy and          ratio between the value of the baseline hair count taken
lower optical energy is more efficient.                     immediately pre-treatment and the value obtained at
                                                            the 3-month post-treatment hair count.

  Figure 1. Treated site before and immediately after the treatment Left: total treated area. Right: treated area
                                               under zoom (x80).
Table 3.                                                    Prior to treatment, a rectangular section of the patient`s
                                                            scalp, on the posterior aspect of his Hippocratic
Site               Average Clearance                        Crown, was shaved. Two pulses were applied to the
Axilla             64%                                      shaved skin. After 30 minutes, 5cc of Lidocain 1%
Bikini Line        60%                                      with Adrenalin was injected and a strip of skin with the
Legs               53%                                      follicles included was withdrawn with a multiblade
Trunk              50%                                      scalpel. The scalpel was manipulated in a direction
Face               62%                                      perpendicular to the follicle in order to provide a view
                                                            of the follicle cross-section at the depth of 3.5mm.
Discussion                                                  Using this procedure, it was possible to recognize and
The clinical study results show that the best clearance     photograph the immediate effect of the RF and optical
was obtained at the facial site, with 68% reduction in      energies on the hair follicle. The specimen was then
hair. In most of the cases, the maximal RF energy (15-      sent to a laboratory, where the histological report and
20 J/cm3 ) was used. The level of optical energy varied,    related pictures were produced.
in the range of 15-28J/cm2 . Analysis of the study
results shows that clearance after 3 months is almost       The histology of the human skin was taken from the
entirely unrelated to the level of optical energy. In the   human scalp before and after treatment. Figure 2
optical energy range of 20-30 J/cm2 , results showed        shows histology taken at the edge of the treated area.
that clearance was determined by the level of RF            The right hand side of the photograph shows a normal
energy, and that a higher RF energy level, in the range     follicle that was further from the center of the treated
of 15-20 J/cm3 , should be used.                            spot. There was no damage observed in this hair and
In order to understand the effect of the combination of     follicle.
conducted RF and light on the hair follicle at a depth of   In the left follicle, a kind of melting of the follicle
at least 2mm, a specific microscopic and histological       structure is clearly visible, particularly when it is
study was performed at the Suntek2 institute in             compared with the right follicle, which was not
Verona, Italy. A 45-year-old male patient, with             damaged.
Fitzpatrick`s skin type 3 and black hair, was accepted
for treatment with the Aurora DS hair removal system
under clinical study conditions.

Figure 2. Skin with hair follicle histology at the depth of 3.5mm following treatment with Aurora DS.

                                                           removal in a broad cross section of the patient
Conclusion                                                 population.
Hair removal methodologies based purely on photo-
epilation systems (whether laser-based or using intense    References
flash lamps) have reached their full potential for         1.   M.C. Grossman C. Dierickx, W. Farinelli, T.
efficacy and safety. Efforts to improve safety by using         Flotte, R. Anderson, Damage to hair follicle by
wavelengths that are not highly absorbed by melanin             normal mode ruby laser pulses. J Am Acad
have not proven entirely successful, as the milder              Dermatol 1996, 35: 889-894
effect on the epidermis comes at the expense of            2.   M.H. Gold, M.W. Bell, T.D. Foster, S. Street,
efficacy in destroying the hair follicle.                       Long term epilation using the Epilight broad
The current study of a combination of conducted RF              band, intense pulsed light hair removal system.
and optical energies for hair removal, as delivered by          Dermatol Surg 1997, 23:909-913
the Aurora DS hair removal system, showed that an          3.   P.L. Bencini, A. Luci, M. Galimberti, G. Ferranti,
energy pulse strong enough to cause the destruction of          Long-term Epilation with long-Pulsed
the hair follicle can be safely delivered without               Neodimium:YAG laser., Dermatol. Surg., 1999,
damaging the surrounding tissue. When pulses of RF              25:3: March:175-178.
energy in the higher range of 15-20 J/cm3 , combined       4.   V. Nururkar, The safety and efficacy of the long-
with optical energy in the range of 15-25 J/cm2 and             pulse alexandrite laser for hair removal in various
epidermal cooling, were applied to various body sites           skin types. Lasers Surg Med, 1997,
on the study subjects, no adverse effects were                  10(suppl):189
observed. Zoom photography and histological study          5.   B. Anvari, B.S. Tanenbaum, T.E. Milner, et al.,
immediately post-treatment showed that the required             Selective cooling of biological tissues:
coagulation of the perifollicular tissue had been               Application for thermally mediated therapeutic
achieved, and clinical examination and hair count               procedures. Physics in Medicine & Biology,
proved a high clearance rate (50-64%, depending on              1995, 40:241-252.
body site) at 3 months post-treatment.
The treatments were well t lerated by the subjects,
none of whom required topical or other anesthesia. The
only post-treatment side effect observed was transient
erythema, which disappeared within a few hours.
The efficacy, absence of adverse side effects, and ease
of patient experience shown in the clinical study prove
that the combination of conducted RF energy and
optical energy, as delivered by the Aurora DS hair
removal system, is an excellent methodology for hair


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