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Wetenschappelijk onderzoek

Woman holding breadfruit - Gauguin
met dank voor de reproductie aan: Tigtail

SAMENVATTING van het onderzoek hieronder: getest is de veiligheid van behandelingen met het ELOS-apparaat (verbeterde IPL) op donkere huid, en of de milde instelling nog effect heeft qua ontharing. Dit werd gedaan op 10 vrijwilligers, waarvan 3 mensen de donkerste huid hadden die bestaat (type VI). Zij werden 1 keer behandeld, en vervolgens gedurende 7 maanden ge-observeerd. Er bleken totaal geen bijwerkingen te zijn. De milde instelling van het apparaat had voor twee personen (type V) geen haarreductie gebracht, maar de andere acht mensen hadden wel een reductie al na 1 behandeling, varierend van 13 tot 75.4 % .

Normaliter, met lichtbehandelingen zoals Laser en Intense pulsed light (IPL), worden veel Joules per cm2 toegediend, of wordt een te korte puls gebruikt, hetgeen bij huidtype IV en V het risico op schade aan pigmentcellen en blaarvorming 18 tot 38% maakt (schade aan pigmentcellen = tijdelijke uitschakeling van deze cellen, resulterend in witte of donkere vlekken waarvan het heel lang duurt totdat ze weggaan). Over de pigmentstoringen bij nog donkerder huid, type VI, wordt in de bestaande onderzoeken nauwelijks iets vermeld. De auteur heeft kritiek op de andere behandelvormen en de onderzoekers die zich ermee bezig houden, zowel in de inleiding als in de discussie aan het einde.

Dr. Laughlin concludeert dat de RF-techniek de voorlopige beste oplossing is omdat de gebruikte RF energievorm die toegediend wordt niet door huidpigment wordt opgenomen.

Epilation in dark skin (types V and VI) with integrated radio-frequency and optical energy.

Sharyn A. Laughlin MD, FRCP(C). Assistant Professor, Department of Medicine, Division of Dermatology
University of Ottawa. Director. Photobiology Unit, Ottawa Civic Hospital.

This material represents a preliminary report on research in progress and is not a formal publication. This summary was prepared at the request of Syneron Corporation to provide information on the use of the Aurora DS system for hair removal. The system used to perform this study and any technical services required were provided by Syneron. The author has received no personal compensation from, nor does she have any financial interest in Syneron Corporation.

INTRODUCTION
Epilation with laser or intese pulsed light is now an established alternative to electrolysis for the removal of unwanted hair in clinical practice. Most systems provide a reliable, usually complete, but temporary loss of hair by inducing prolonged telogen. Published reports confirm that certain lasers emitting wavelengths in the red and near infra-red area of the electromagnetic spectrum produce varying degrees of permanent hair loss.(1,2) It appears that there is a dose response relationship for extended telogen versus permanent hair loss. Although lower fluences can achieve permanent reduction in some patients, it is generally attained using high fluences of 30J/ cm2 or above. (3,4,5) At the fluences effectieve for long-term or permanent hair reduction the risk of epidermal injury and dyschromia increase, particularly with tanned, olive-colored (type III), dark (types IV and V), and black skin (type VI). (4)
The use of red light at 694-755 nm in pulse durations between 3-10 milliseconds with various methods of epidermal cooling is associated with a significant rate of side effects. For type I-V skin the overall rate of dyschromia can reach 20% and the rate of all adverse effects in type IV and V subjects is 18-38%. (6) Longer wavelenghts of 800-1064 nm with 10-100 millisecond pulse widths and epidermal cooling reduce but do not eliminate the risk of adverse effects in skin types III-V. The treatment of black skin remains a problem for which there is limited information.

Unpublished reports and industry literature sugges that Nd:YAG lasers with longer pulses are the most appropriate systems for skin types IV-VI. Yet published reports still describe blistering in 1,5% and dyschromia in 5% of treatment sites from a study group with skin types IV-VI treated with a 50 millisecond Nd:YAG laser. (7)
When pure optical energy is used for epilation the risk of epidermal injury is directly proportional to the fluence used. Photoepilation targets melanin in follicular and adnexal structures to achieve thermal injury but red of infra-red light is also absorbed by melanocytes and keratinocytes in the adjacent epidermis. The Aurora DS delivers a combination of radio frequency (RF) energy and a pulse of red to infra-red light to achieve the heating required for selective thermal injury. The energy deposited in the skin from RF energy is independent of skin colour and there is no epidermal barrier to absorption as occurs with optical energy. Only part of the heat required for selective injury to the target is produced by the fraction of optical energy contained in the electromagnetic pulse. This delivers effective heating and biologic effects at lower levels of optical energy. This should provide a lower risk of adverse effects in contrast to pure light-based treatment.

The use of RF energy to supplement the optical energy applied to the target tissue should allow for treatment of all skin types, since this form of energy is not absorbed by the pigment melanin. RF energy is applied externally by coupling two electrodes to the skin surface. The geometry of the electrodes and the duration of the RF pulse are precisely calibrated to achieve selective heating of the target lesion. During the application of the RF energy, the device measures changes in the skin impedance. There is an inverse relationship between changes in temperature and impedance. This allows the Aurora to perform active dermal monitoring, which makes it a smart device with a unique fail-safe mechanism.

The application of RF and light energy can only occur if the device detects optimal impedance. Active dermal monitoring controls the ratio of RF to light energy. During each pulse the hand piece measures the fall in impedance of the skin as the temperature rises. If the fall in impedance reaches a pre-set level (usually 30%), the device terminates the RF energy. Therefore, the total amount of energy applied to the target is actively regulated by change in temperature. This unique capability ensures that the total energy applied is precisely matched to the energy required for the desired change in temperature. Consequently, this device delivers lower levels of optical energy than other systems currently used. Active dermal monitoring should improve the therapeutic margin of safety and reduce the incidence of adverse effects.

OBJECTIVE
The purpose of the study was to determine the efficacy and safety of the Aurora DS device (Syneron Medical) for epilation in subjects with type V and type VI skin.

PATIENTS AND METHODS
Ten adult patients were selected for the study. All participants were screened for exclusion criteria of diabetes, photosensitivity, a history of keloid scarring, or therapy with Accutane within the past year, and current aspirin or iron therapy. There were 4 maile and 6 female volunteers. the study group xonsisted of 7 East Indian patients with Fitzpatrick type V skin and 3 black patients with Fitzpatrick type VI. Body sites with uniform hair density were selected and an area measuring 2 x 4 inches was mapped for treatment. the distribution according to anatomic site was axilla (6), back (2), lateral face (1), and abdomen (1).

Informed consent was obtained and each study site was mapped. the area was first shaved leaving residual `stubble' of approximately 1mm. and a photograph taken to be used for the calculation of a baseline hair count. A close shave of the selected area was carried out prior to treatment. No topical or local anesthetic was employed
An Aurora DS system delivering RF and optical energy in an integrated pulse profile was used to perform the study. The geometric design of the RF electrodes conducts energy through the skin to a depth of 4 mm. Three equal pulses of light for a total duration of 25 milliseconds are emitted at calculated intervals during an RF pulse of 200 milliseconds. The optical energy delivered is a spectrum of light in a waveband from 680-980 nanometers. The device provides contact epidermal cooling through the hand piece applicator and maintains skin temperature at around 5 degrees Centigrade. A transparant water-based gel was used as a contact medium and light pressure on the applicator during treatment ensured proper coupling of the electrodes to the skin.

The level of RF energy was set at 18 joules/ cm3 for type V skin and at 20 joules / cm3 for type VI skin. Test pulses were carried out on an area adjacent to the study site to determine the level of optical energy suitable for each patient. For patients with type V skin optical energy of 16 joules / cm2 and for type VI skin 14 joules/ cm2 was used as a starting point. Each pulse was increased by increments of 1 joule / cm2. The energy level at which each patient first experienced discomfort was selected to carry out the study treatment. The range of fluences used for the study was 16-20 joules / cm2 for type V subjects and 14-17 joules / cm2 for type VI subjects. Pulses were placed in an adjacent non-overlapping pattern over the entire study site using the Aurora DS device.

Serial photography and clinical examination were used to evaluate the subjects at 1-3 days, 2 weeks, 1 month, and at 4-7 months to determine hair loss and whether any complications had occurred. the last photograph at 4-7 months was used to calculate a hair count and determine the incidence of any long-term complications, notably dyschromia and scarring. Values for hair counts before and after treatment were obtained by photometric analysis of magnified images projected on to a white background. Counting was carried out over the entire treatment area by two blinded observers working independently and an average determined for each value. The percentage hair loss was calculated for each study volunteer.

RESULTS
Fifty percent (5/10) of the subjects obtained a hair loss of more than 35% and the mean hair loss for the entire group was 30.20 (SD = 7.59), with a range of 13 to 75,4%. There were two patients with type V skin who showed no change in hair counts. The three patients with black skin achieved a mean hair loss of 29% without any instances of epidermal injury, dyschromia or scarring at 2 weeks, 1 month and 3 months after the treatment.

Figure 1 shows a patient with type VI skin who obtained a 55% hair loss in the axilla at 4 months after a single treatment. In the entire group there were no cases with blistering at the 1-3 follow-up visits and the overall rate of complications was zero.
(de betreffende foto konden we helaas niet goed genoeg kopieren om hier over te nemen -red.)