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Optimizing treatment parameters for hair removal using long-pulsed Nd:YAG-lasers
Abstract
Our aim was to determine the most effective treatment parameters for laser-assisted hair removal using long-pulsed Nd:YAG-lasers. 42 volunteers were treated with 1064 nm long-pulsed Nd:YAG-lasers. We used two different laser systems (Lyra XP, Wavelight and Smartepil II Deka-LMS) with various pulse lengths, fluences, and spot sizes. For each parameter, five test areas were treated one to five times at 4-week intervals. Follow-ups were performed 1, 3, 6, and 12 months after the last treatment. Percentual hair loss, side effects, and pain during treatment were evaluated. The average hair reduction 12 months after the last treatment using the Lyra XP was 48%, using the Smartepil II it ranged between 30% and 35%. There were no permanent side effects. Long-pulsed 1064 nm Nd:YAG-lasers are safe and effective for hair reduction. Although the different treatment parameters did not lead to a lot of differing hair reduction 12 months after the last treatment, the laser with the largest spot size and the longest pulse time showed the best results.
... 4,5 However, the management of dark skin phenotypes remains problematic because melanin pigments in the epidermis competitively absorb light intended for hair follicle melanin pigments, the primary target of photoepilation. [6][7][8][9][10] IPL is a high-intensity polychromatic light. Unlike laser systems, these flashlamps work by using incoherent light in the wavelength range 515-1,200 nm, 11 and by using different filters, a wide range of wavelengths are possible for IPL systems. ...
... 26 The thermal relaxation time (TRT) is defined as the time taken for an increase in temperature to reduce by 1/2 of its peak value. A pulse time substantially longer than the TRT reduces heat conduction from the target to adjacent tissue, 9 whereas too short a pulse time is likely to develop an epidermal burn. The TRT of epidermal melanosomes is 1 to 2 ms, and that of a hair shaft, 40 to 100 ms. ...
... Since recently, longer pulse widths are favored to improve clinical efficacy without significantly increasing the risk of adverse effects. 5,9,27,28 Dierick. 29 argued that the actual target during hair removal is not the pigmented structure, but rather components removed from a pigmented struc-ture, like the follicular stem cells that lie in the hair follicle outer root sheath. ...
BACKGROUND: Recently, intense pulsed light (IPL) sources have been shown to provide long-term hair removal. OBJECTIVE: This study examined the photoepilatory effects of different wavelengths and pulse width application in the same device and compared their efficiencies in Asian skin. METHODS: Twenty-eight Korean women were treated using HR (600–950 nm filter) and 27 using HR-D (645–950 nm filter) in the axillar area. Four treatments were carried out at intervals of 4 to 6 weeks; follow-ups were conducted 8 months after the last treatment. Mean energy settings were 14.9±2.0 J/cm2 for HR and 17.1±0.6 J/cm2 for HR-D. Longer pulse widths were applied in case of HR-D treatment. Hair counts and photographic evaluation of skin sites were made at baseline and at the last follow-up. Final overall evaluations were performed by patients and clinicians. RESULTS: Average clearances of 52.8% and 83.4% were achieved by HR and HR-D, respectively. No significant adverse effects were reported after HR-D treatment. One case each of hypopigmentation and hyperpigmentation was reported for HR. CONCLUSION: An IPL source by removing 45 nm of the emitted spectra and applying longer pulse width was found to provide a safer and more effective means of photoepilation in Asian patients.
... 4,5 However, the management of dark skin phenotypes remains problematic because melanin pigments in the epidermis competitively absorb light intended for hair follicle melanin pigments, the primary target of photoepilation. [6][7][8][9][10] IPL is a high-intensity polychromatic light. Unlike laser systems, these flashlamps work by using incoherent light in the wavelength range 515-1,200 nm, 11 and by using different filters, a wide range of wavelengths are possible for IPL systems. ...
... 26 The thermal relaxation time (TRT) is defined as the time taken for an increase in temperature to reduce by 1/2 of its peak value. A pulse time substantially longer than the TRT reduces heat conduction from the target to adjacent tissue, 9 whereas too short a pulse time is likely to develop an epidermal burn. The TRT of epidermal melanosomes is 1 to 2 ms, and that of a hair shaft, 40 to 100 ms. ...
... Since recently, longer pulse widths are favored to improve clinical efficacy without significantly increasing the risk of adverse effects. 5,9,27,28 Dierick. 29 argued that the actual target during hair removal is not the pigmented structure, but rather components removed from a pigmented struc-ture, like the follicular stem cells that lie in the hair follicle outer root sheath. ...
BACKGROUND Recently, intense pulsed light (IPL) sources have been shown to provide long-term hair removal.OBJECTIVE This study examined the photoepilatory effects of different wavelengths and pulse width application in the same device and compared their efficiencies in Asian skin.METHODS Twenty-eight Korean women were treated using HR (600–950 nm filter) and 27 using HR-D (645–950 nm filter) in the axillar area. Four treatments were carried out at intervals of 4 to 6 weeks; follow-ups were conducted 8 months after the last treatment. Mean energy settings were 14.9±2.0 J/cm2 for HR and 17.1±0.6 J/cm2 for HR-D. Longer pulse widths were applied in case of HR-D treatment. Hair counts and photographic evaluation of skin sites were made at baseline and at the last follow-up. Final overall evaluations were performed by patients and clinicians.RESULTS Average clearances of 52.8% and 83.4% were achieved by HR and HR-D, respectively. No significant adverse effects were reported after HR-D treatment. One case each of hypopigmentation and hyperpigmentation was reported for HR.CONCLUSION An IPL source by removing 45 nm of the emitted spectra and applying longer pulse width was found to provide a safer and more effective means of photoepilation in Asian patients.
... 2,3 Lasers most commonly in use for hair removal include alexandrite, neodymium: yttrium-aluminum-garnet (Nd:YAG) and diode. [4][5][6][7][8][9][10][11] Currently, laser hair removal is being performed using either a stamping or a brushing ("in-motion") technique. 6 With the "stamping" technique the laser handpiece is positioned over the treated skin from spot to spot without any overlapping, and single high fluence pulses are delivered at a relatively low repetition rate to each of the spots. ...
... 5 This technique is most commonly being used with Nd:YAG and alexandrite lasers since these lasers are able to deliver high energy laser pulses with sufficiently short pulse durations (~0.3-25 ms). [7][8][9][10][11] Using this technique the hair follicles are targeted directly by selectively over-heating the hair with individual pulses with durations shorter than the thermal relaxation (i.e., cooling) time of the hair. ...
Background and objectives:
In this study, we investigate the photothermal response of human hair using a pulsed laser source employed in the hair removal treatment. The purpose is to understand the dynamics behind the most common clinical practice to better define the salient features that may contribute to the efficiency of the process.
Study design/materials and methods:
Temperature changes of hair samples (dark brown color) from a human scalp (skin type Fitpatrick II) were measured by a thermal camera following irradiation with single and multiple neodymium: yttrium-aluminum-garnet (Nd:YAG) (1064 nm) and alexandrite (755 nm) laser pulses. Particularly, the hair was treated with an individual laser pulse of a sufficiently high fluence, or with a series of lower fluence laser pulses. We investigated the temperature increase in a broad range of fluence and number of pulses. From the data analysis we extrapolated important parameters such as thermal gain and threshold fluence that can be used for determining optimal parameters for the hair removal procedure. Our experimental investigations and hypothesis were supported by a numerical simulation of the light-matter interaction in a skin-hair model, and by optical transmittance measurements of the irradiated hair.
Results:
An enhancement of the temperature response of the irradiated hair, that deviates from the linear behavior, is observed when hair is subjected to an individual laser pulse of a sufficiently high fluence or to a series of lower fluence laser pulses. Here, we defined the nonlinear and rapid temperature built-up as an avalanche effect. We estimated the threshold fluence at which this process takes place to be at 10 and 2.5 J/cm2 for 1064 and 755 nm laser wavelengths, respectively. The thermal gain expressed by the degree of the deviation from the linear behavior can be higher than 2 when low laser fluence and multiple laser pulses are applied (n = 50). The comparison of the calculated gain for the two different laser wavelengths and the number of pulses reveals a much higher efficiency when low fluence and multiple pulses are delivered. The avalanche effect manifests when the hair temperature exceeds 45°C. The enhanced temperature increase during the subsequent delivery of laser pulses could be ascribed to the temperature-induced changes in the hair's structural properties. Simulations of the hair temperature under Nd:YAG and alexandrite irradiation indicate that the avalanche phenomenon observed in the hair suspended in air may apply also to the hair located within the skin matrix. Namely, for the same fluence, similar temperature increase was obtained also for the hair located within the skin.
Conclusion:
The observed "avalanche" effect may contribute to the reported clinical efficacy of laser hair removal and may at least partially explain the observed efficacy of the brushing hair removal procedures where laser fluence is usually low. The repeated irradiation during the brushing procedure may lead to an avalanche-like gradual increase of the hair's thermal response resulting in sufficiently high final hair temperatures as required for effective hair reduction.
... Ismail reported that at the six-month follow-up after all the procedures, patients treated with long-pulsed Nd:YAG laser experienced a 79.4% decrease in hair count [16]. Other studies reported a decrease in hair count from 50 to 60%, but this variability may be associated with the researcher experience, as well as with a different treatment protocol [17,18]. Recently, short-pulsed Nd:YAG laser has been proposed for hair removal, with results that need further confirmation [19]. ...
Background and Objectives: Hair removal is a common cosmetic problem interesting more and more patients nowadays. Various laser treatments are currently available. Alexandrite and Nd:YAG laser are the most effective procedures in lighter and darker skin phototypes, respectively. Materials and Methods: A total of 40 patients seeking hair removal in one or more body areas with skin phototypes 2–6 was recruited to perform this study. Patients were divided into two groups. One group was treated with the standard Nd:YAG hair removal procedure, while the other group was treated with a new “in motion” Nd:YAG technology. Results and hair removal rates were evaluated six months after the last treatment. Results: Out of 40 patients treated, all patients experienced hair reduction. No statistically significant difference in hair removal was noted between the two groups; however, a statistically significant reduction in pain during the procedure was observed in the group treated with the “in motion” technique. Conclusions: While traditional and “in motion” Nd:YAG techniques have similar result outcomes in hair removal, the “in motion” technology seems to guarantee a better safety profile compared with the traditional technique. A more extensive clinical study will be necessary to confirm our study’s results.
... It tended to resolve within two hours to fourty eight hours. We also applied topical mometasone on the effective area to reduce the erythema and edema 4,5,6 . ...
... This minimizes damage to the surrounding tissues, which have different thermal relaxation times. However, the management of dark skin in human and mice induce untoward slim damage because melanin pigments in the epidermis competitively absorb light intended for hair follicle melanin pigments, the primary target of photoepilation (10). A histological study on photoepilation in mice (9) has revealed that anagen follicles are far more sensitive to this procedure, suggesting that anagen pigmentation and or active growth are important determinants of photothermal damage to hair follicles. ...
The presence of excessive perioral hair in women is associated with psychological and emotional distress, and
causes significant impairment of their quality of life. The aim of the present study is to show the efficacy of intense
pulsed light (IPL) device in a mouse model. Thirty female, 6-8 weeks-old black-haired mice were selected. Mices
were divided into five groups, each of six subjects, and were anaesthetized; the first five groups were only shaved
with electric razor and waxing, while the other groups, after shaving of back, they were treated with the light of
an intense pulsed light source device (590-1200 nm, spot size 20x50 mm-pulse duration 5-105 msec) (MED-LITE
device, Dermal Medical, Bologna-Italy). All mices (Test group) received 12 sessions of treatment at 1 week interval.
Hair counts and photographic evaluation of skin sites were made at baseline and at the last follow-up after the
following time intervals: 4, 8, 12 weeks. All mices were evaluated after the following time intervals: 4, 8, 12 weeks.
A statistically significant difference was present between hair reduction after treatment in control group vs. test
(control vs. test) p-value = 0.08 after 4-8 and 12 weeks. We suggest that both intense pulsed light sources could
reduce the hair even.
Laser hair reduction functions based on the extended theory of selective photothermolysis. Hair follicles in anagen are most susceptible to the thermal damage that leads to the reduction of hairs. A wide range of laser and other energy-based device systems have been employed, either singly or in combination, for hair removal. These include the long-pulsed ruby laser (694 nm), alexandrite laser (755 nm), diode laser (810 nm), and neodymium-doped yttrium-aluminium-garnet (Nd:YAG) laser (1064 nm), as well as intense pulsed light (IPL) therapy. Pain, erythema, and perifollicular oedema are commonly experienced by patients immediately after the procedure. Post-inflammatory hyperpigmentation, lasting up to months, may also result, especially in darker skin phototypes. The use of longer wavelengths and pulse durations, coupled with appropriate cooling measures, can help to enhance the safety profile of laser hair reduction.
By controlling the light wave-form of Xe lamp with insulated gate bipolar transistor(IGBT) and using the periodic long-pulse chopper technology, a long pulsed medical Nd:YAG laser was designed. It can enlarge the safe operating area(SOA) of the IGBT module, and make the IGBT work more stably. It has higher electronic-optic efficiency because of its higher pumping power. it can reduce the skin thermal effect and prevent the skin from heat injury during the hair removal treatment. So a long phase laser with wavelength of 1064 nm, energy of 50 J, pulse duration from 9 ms to 99 ms, was obtained.
Laser physics, safety and a greater understanding of the concept of selective photothermolysis has led to a proliferation of lasers and laser like devices over the last 20 years. The treatment of vascular lesions was followed by the development of pigment specific lasers in the 1980s. In the 1990s ablative laser resurfacing (and non-ablative dermal remodeling) and the laser and light source treatment of unwanted hair became very popular techniques. This article will present 4 of the most recently developed techniques in the laser and laser like arena. Topics to be addressed are fractional resurfacing as an alternative for ablative and non-ablative resurfacing; cosmetic photodynamic therapy; radiofrequency for skin tightening; and the treatment of unwanted hair in darker skin types. It is recognized that all 4 areas are controversial. However, 20 years ago the treatment of children's port-wine stains was also controversial. There will continue to advances in laser dermatology.
This chapter discusses melanogenesis in skin and hair follicle, how melanin granules or melanosomes are formed, some basic thermal principles describing how hair follicles respond to heat, the relevance of using the Fitzpatrick scale, various cooling systems designed to protect the epidermis, and the efficacy and safety of various lasers and IPL systems for darker skin types. Laser hair removal allows a physician or trained professional to treat large areas of the body quickly, with long-lasting or permanent reduction in hair growth. These reductions in growing hair are caused by the interaction of the laser with the hair melanin. While initially developed for the ideal contrast of dark hair against a fair skin background, an increasing demand is foreseen to treat all individuals regardless of base skin color, particularly in the United States, where the population is becoming more ethnically diverse. Significant hair growth reduction has been reported in people with darker skin types; however, the interaction of the laser with skin melanin must be taken into account to prevent long-lasting side effects. Permanent changes in pigmentation and skin texture, focal atrophy, and scarring are some of the adverse effects that have been reported with improper laser use. As the understanding of the variations in response in people of color to the laser grows, these side effects associated with laser hair reduction can be reduced.
This chapter reviews the most popular laser devices commonly used today, which include the alexandrite, diode, and 1064 Nd:YAG lasers. In addition, intense pulsed light (IPL) devices for hair removal are now growing in popularity, and they are also reviewed. Many different light-based systems can successfully remove unwanted hair. The majority of laser and light-based systems used today appear to be equivalent in efficacy. The decision of which system to use is likely to be based largely on practitioner experience with a particular system and also on patient population treated. Although significant advances in light-based hair removal have been made, questions as to appropriate treatment intervals remain. It is clear that a simple understanding of anagen and telogen cycles do not adequately predict what time intervals between laser sessions are optimal. Finally, home-based light-based hair removal systems are soon to be available throughout the world. These technologies have the potential to replace other temporary home-based methods for the removal of unwanted hair. It can be expected that home-based devices will deliver lesser energies than seen with the larger office-based units, making them quite safe. However, the lesser-delivered fluences will also make them less effective. How these home-based devices will affect the office-based laser hair removal market is yet to be determined.
Although long pulsed Nd:YAG laser is effective and safe for hair removal, especially in dark individuals, hair regrowth may only be delayed, not permanently lost [1]. This study aimed at evaluating the effect of increasing the pulse duration of long pulsed Nd:YAG, with or without increasing fluence, on hair growth impairment. The study included 30 hirsute females (mean age: 29.93 years ± 5.53). Skin types included type III in 6 (20%) cases and type IV in 24 (80%) cases.The Synchro HP platform [...]
A novel self-induced, non-ablative, three-dimensional fractional FRAC3 ® method for skin treatments is described. The method utilizes the short pulse duration and high peak power density of Accelera mode, Nd:YAG laser pulses. The Accelera Nd:YAG pulses produce a three-dimensional fractional pattern in the epidermis and dermis, with damage islands that are predominantly located at the sites of skin imperfections. In-vivo thermal measurements of the skin surface and in-vitro measurements of skin cross-sections, following illumination with Accelera Nd:YAG pulses are presented. The measurements demonstrate the emergence of isolated »fractional« hot islands within the skin. Clinical results following Accelera Nd:YAG laser treatments are also presented. The FRAC3 ® method offers practitioners another dimension of safety and self-regulating efficacy in non-ablative treatments such as skin rejuvenation and hair removal.
Basierend auf der 1916 von Albert Einstein inaugurierten Theorie der stimulierten Emission von Licht wurden in den 1960er-Jahren die ersten Laser entwickelt. Der erste klinische Einsatz eines Lasers in einer Universitätshautklinik in Deutschland erfolgte 1978 in der Dermatologischen Klinik der Ludwigs-Maximilian-Universität München unter der Leitung des damaligen Direktors, Herrn Prof. Dr. med. Dr. h.c. mult. O. Braun-Falco. Seitdem ist eine rasante Weiterentwicklung der Lasermedizin zu verzeichnen. Heute ist die Lasertechnologie eine interdisziplinär genutzte Therapieform, die insbesondere in der Dermatologie klinisch wie auch wissenschaftlich fest verwurzelt ist. Die Behandlung zahlreicher Indikationen der klassischen und auch der ästhetischen Dermatologie erfolgt heute standardmäßig – teilweise ausschließlich – mittels Lasertechnologie. In der vorliegenden Arbeit soll auf aktuelle Entwicklungen der Lasermedizin eingegangen werden. Hier zeichnet sich in der jüngsten Vergangenheit ein Trend zu Kombinationsbehandlungen ab. Mit dem Ziel der Wirkungsverstärkung werden hierbei verschiedene Lichtsysteme komplementär angewendet oder der Laser mit einer dezidierten Arzneimittelapplikation kombiniert.
A variety of laser systems with varying wavelengths, pulse durations, spotsizes and energy fluences are currently used for hair removal. In this paper VSP Nd:YAG laser efficacy and safety were evaluated. We found that the modern, high-power, second generation VSP Nd:YAG laser systems with cold air cooling and scanner technology gave the best possibilities to adjust treatment parameters to the individual cases and thus optimize treatment efficacy while preserving the epidermis from unwanted damage.
Introduction:
Laser hair removal is becoming an increasingly popular alternative to traditional methods such as shaving, waxing, among other methods. Semiconductor diode lasers are considered the most efficient light sources available and are especially well suited for clinical applications including hair reduction. The effectiveness of laser hair reduction depends on many variables, including the skin type of the patient.
Material and methods:
A patient with Fitzpatrick Skin Type IV was submitted to laser hair removal of the arms with a high-power diode laser system with long pulses with a wavelength of 800 nm, a fluence of 40 J/cm(2) and a pulse width of 20 ms. A 12-month follow-up assessment was performed and included photography and questionnaire.
Results:
Hypopigmentation was observed after a single laser hair removal section. After 6 months with the area totally covered, a gradual suntan with a sun screen lotion with an SPF of 15 was prescribed by the dermatologist. After 12 months of the initial treatment, a complete recovery of the hypopigmentation was achieved.
Conclusion:
Although a safe procedure, lasers for hair removal may be associated with adverse side effects including undesired pigment alterations. Before starting a laser hair removal treatment, patients seeking the eradication of hair should be informed that temporary, and possibly permanent, pigmentary changes may occur.
The objective of this work is the investigation of intense pulsed light (IPL) photoepilation using Monte Carlo simulation to model the effect of the output dosimetry with millisecond exposure used by typical commercial IPL systems. The temporal pulse shape is an important parameter, which may affect the biological tissue response in terms of efficacy and adverse reactions. This study investigates the effect that IPL pulse structures, namely free discharge, square pulse, close, and spaced pulse stacking, has on hair removal. The relationship between radiant exposure distribution during the IPL pulse and chromophore heating is explored and modeled for hair follicles and the epidermis using a custom Monte Carlo computer simulation. Consistent square pulse and close pulse stacking delivery of radiant exposure across the IPL pulse is shown to generate the most efficient specific heating of the target chromophore, whilst sparing the epidermis, compared to free discharge and pulse stacking pulse delivery. Free discharge systems produced the highest epidermal temperature in the model. This study presents modeled thermal data of a hair follicle in situ, indicating that square pulse IPL technology may be the most efficient and the safest method for photoepilation. The investigation also suggests that the square pulse system design is the most efficient, as energy is not wasted during pulse exposure or lost through interpulse delay times of stacked pulses.
PACS number: 87.10.Rt
Based on the theory of stimulated emission of radiation that was proposed by Albert Einstein in 1916, the first lasers were developed in the 1960s. The first clinical use of laser technology in a German university took place in 1978 in the Department of Dermatology of the Ludwig-Maximilian-University in Munich under the guidance of the former director, Prof. Dr. med. Dr. h.c. mult. Otto Braun-Falco. In the following years, laser technology developed rapidly. Today laser technology is a widely used interdisciplinary therapeutic procedure that has deep clinical and scientific roots in dermatology. There are many conditions in both classic and aesthetic dermatology that are routinely - and sometimes exclusively - treated with lasers. Here we review recent developments in laser medicine. There seems to be a trend to combination procedures. To enhance efficacy, different laser systems are together or lasers are combined with specific topical medications.
Laser hair removal at lower fluences, delivered under certain conditions, may retain the efficacy of high-fluence lasers while improving tolerability. We performed a pilot study comparing the efficacy, safety and tolerability of laser hair removal using traditional settings compared to lower fluences, delivered from a larger handpiece and under vacuum.
Fourteen healthy participants underwent 5 axillary hair removal treatments with an 800 nm diode laser at 1-month intervals, with follow-up 1 and 3 months after the 5th treatment. In all patients, one side was treated with standard parameters using a 9×9 mm chilled tip and gel, while the contralateral side was treated using a 22×35 mm vacuum-assisted handpiece at fluences up to 12 J/cm(2). Follow-up assessments were performed after each treatment and at each follow-up visit, and included photography and questionnaires.
Eleven participants completed the study and follow-up. All experienced significant hair removal in all treated areas. At the 3-month follow-up visit, the high-fluence and low-fluence treated axillae demonstrated comparable hair reduction. Participants found the lower fluence treatments to be more tolerable. No adverse events were reported.
Lower fluence diode laser, delivered under conditions of vacuum and using larger spot sizes, can provide significant hair reduction.
Recently, intense pulsed light (IPL) sources have been shown to provide long-term hair removal.
This study examined the photo-epilatory effects of different wavelengths and pulse width application in the same IPL device and compared their efficiencies in Asian skin.
Twenty-eight Korean women were treated using hair removal (HR) (600-950 nm filter) and 27 using HR-D (645-950 nm filter) in the axillary area. Four treatments were carried out at intervals of 4 to 6 weeks; follow-ups were conducted 8 months after the last treatment. Mean energy settings were 14.9 6 2.0 J/cm2 for HR and 17.1 6 0.6 J/cm2 for HR-D. Longer pulse widths were applied in case of HR-D treatment. Hair counts and photographic evaluation of skin sites were made at baseline and at the last follow-up. Final overall evaluations were performed by patients and clinicians.
Average clearances of 52.8% and 83.4% were achieved by HR and HR-D, respectively. No significant adverse effects were reported after HR-D treatment. One case each of hypopigmentation and hyperpigmentation was reported for HR.
An IPL source removing 45 nm of the emitted spectra and applying a longer pulse width was found to provide a safer and more effective means of photo-epilation in Asian patients.
Medical spas are the fasting growing segment of the 15-billion dollar spa industry. Although medical spas have been in existence since ancient times to treat a wide variety of ailments such as gout, arthritis, and diabetes, our modern concept of the medical spa combines relaxation with medical rejuvenative procedures. This article focuses on the more recent technologic advancements in rejuvenation.
Background. Lasers with long wavelengths are less well absorbed by melanin and are considered to be particularly suitable for hair removal in dark-skinned patients.Objective. To compare the efficacy and complications of 800 nm diode and long-pulsed 1064 nm Nd:YAG lasers in laser-assisted hair removal in Chinese patients.Methods. Fifteen women had hair removal treatments (13 axillae and 2 legs) with diode laser on one side and Nd:YAG laser on the other. They were followed up for 36 weeks. Subjective assessments included the degree of immediate pain and the degree of hair regrowth. Clinical photographs were taken for evaluation by two independent observers to assess complications and the degree of hair regrowth.Results. Long-pulsed Nd:YAG laser was found to be significantly associated with a greater degree of immediate pain after laser surgery (P = .0001, independent sample t-test) and also had a longer laser time (P = .0001, independent sample t-test). Besides transit adverse effects such as erythema and perifollicular edema, only one patient developed hypopigmentation at week 6 which resolved by week 36. Although regrowth rates were low at week 6 (subjective rates were 23% and 19% for Nd:YAG and diode laser, respectively), most patients had significant regrowth at week 36 (subjective regrowth rate 91% for both long-pulsed Nd:YAG and diode lasers).Conclusion. Diode 800 nm and Nd:YAG 1064 nm lasers are safe in laser-assisted hair removal in Chinese patients, and besides immediate pain, there was no other significant adverse effect. Most patients experienced regrowth 36 weeks after a single treatment. Further study is necessary to determine the long-term clinical efficacy and complications of laser-assisted hair removal with these systems in dark-skinned patients.
Die rasante Entwicklung verschiedener Licht- und Lasergeräte zur Photoepilation sowie deren unkritische Darstellung in den
Medien haben in den letzten Jahren bei Ärzten und Betroffenen für Verwirrung gesorgt. Ziel dieser Arbeit ist es, eine strukturierte
Übersicht über die in Deutschland verfügbaren gepulsten Licht- und Lasergeräte (Epilight™, Photoderm®, langgepulster Rubin-, Alexandrit- und Diodenlaser) einschließlich deren Begleitreaktionen, Nebenwirkungen und Komplikationen
zu geben. Daneben wird der aktuelle Stand der wissenschaftlichen Forschung auf diesem Gebiet vorgestellt und diskutiert.
During the last few years the fast development of different laser and laser-like systems for photoepilation and their one-sided
representation in media has led to confusion among pysicians and patients. The object of this review is to give a structured
report of different pulsed laser and laser-like systems (Epilight™, Photoderm®, long-pulsed ruby-, alexandrite- and diodelaser) that are available in Germany, including their side effects and complications.The
current status of scientific investigation in this field is discussed.
The aim of the present study, which was performed at the dorsal aspects of the ears of guinea pigs, was to compare effects of different lasers on epidermis, dermis, and small venous vessels. Irradiations were performed with argon, dye, and Nd:YAG lasers.
In the first series tissue repair processes were studied after argon laser application. Laser defects were excised after 1, 4, 8, and 14 days and were prepared for routine histological examination. The breadth of epidermal defect and extent of dermal coagulation and occlusion of vessels by thrombus formation were examined histologically. In a second series parameters of irradiation (ie, exposure time, laser power) of the three different lasers were changed systematically. Laser-induced morphological tissue changes could be best observed 24 hours after irradiation. Each of the lasers led to occlusion of vessels by thrombus formation and also coagulated epidermis and dermis. The extent of dermal and epidermal coagulation was less pronounced after dye laser application. Using short exposure times it was possible to reduce the extent of epidermal damage caused by argon and Nd:YAG lasers. Only 50-msec dye laser pulses led to intravascular thrombus formation without epidermal and dermal damage.
Unwanted body hair can represent a severe cosmetic disturbance. The traditional methods used to epilate often have limitations, side effects, and unsatisfactory results. In recent years, various light sources (lasers and others) have been developed for long-term epilation of unwanted hair.
This study evaluates, on a large number of patients, the efficiency and safety of a long-pulsed low-potency Nd-Yag laser invented specifically for long-term hair removal.
Some 208 subjects needing epilation were divided into three groups and treated during an 11-month period. Group A included 79 patients with a normal distribution of unwanted hair; Group B 67 patients with constitutional hypertrichosis; and Group C 62 patients with hirsutism. Treatment sessions were performed with a fluence of 23-56 J/cm2 at 1-month intervals until obtaining desirable results. Follow-ups ranged from 1 to 6 months. In 3 patients 4-mm diameter punch biopsy specimens were obtained before the first session and again after 6 hours. A third biopsy was performed after 3 months.
Every session resulted in a 20-40% hair loss, depending on the color of hair. Complete epilation was obtained in 4 to 6 sessions. Only white hair was not receptive to laser light, and its growth was not modified. No patients, including dark-complexioned patients, had blistering, hypo-or hyperpigmentation. No pain was present during treatment except for the axillary area. In the specimen obtained after 6 hours, very extensive necrosis of the hair follicular and sebaceous gland epithelium was evident. Histologic findings of the biopsies taken after three months showed complete disappearance of hair and moderate fibrosis.
This study proves that the long-pulsed Nd:Yag laser treatment produces an excellent prolonged epilation with no relevant side effects. This laser light, having a 1064 nm wavelength, is minimally absorbed in superficial skin layers, and pronounced scattering up to 5 mm occurs targeting the deeper follicles.
Unwanted hair is a widespread cosmetic problem. Many temporary methods of hair removal have proved unsatisfactory. A variety of laser systems with varying wavelengths, pulse durations, and energy fluences are currently utilized for hair removal. Optimal laser parameters continue to require further investigation.
To evaluate the efficacy and safety of a long-pulse millisecond Nd:YAG hair removal laser utilizing fluences of either 50, 80, or 100 J/cm2.
Fifteen subjects were treated with a contact cooled 50 msec Nd:YAG laser at fluences 30, 50, or 100 J/cm2. Reduction in hair regrowth was measured at 3 months after treatment by comparing the terminal hair count to the baseline values. Potential complications were also evaluated.
Average hair reduction at 3 months after treatment was 29%, 29%, and 27% in areas treated with a 50-msec Nd:YAG laser at fluences of 50, 80, and 100 J/cm2, respectively. Although short-term blistering was noted in two subjects, no hyperpimentation, hypopigmentation, or scarring was observed at 3 months after treatment.
Long-pulse millisecond Nd:YAG laser hair removal with fluences of either 50, 80, or 100 J/cm2 leads to similar efficacy with no significant adverse effects.
Lasers with long wavelengths are less well absorbed by melanin and are considered to be particularly suitable for hair removal in dark-skinned patients.
To compare the efficacy and complications of 800 nm diode and long-pulsed 1064 nm Nd:YAG lasers in laser-assisted hair removal in Chinese patients.
Fifteen women had hair removal treatments (13 axillae and 2 legs) with diode laser on one side and Nd:YAG laser on the other. They were followed up for 36 weeks. Subjective assessments included the degree of immediate pain and the degree of hair regrowth. Clinical photographs were taken for evaluation by two independent observers to assess complications and the degree of hair regrowth.
Long-pulsed Nd:YAG laser was found to be significantly associated with a greater degree of immediate pain after laser surgery (P =.0001, independent sample t-test) and also had a longer laser time (P =.0001, independent sample t-test). Besides transit adverse effects such as erythema and perifollicular edema, only one patient developed hypopigmentation at week 6 which resolved by week 36. Although regrowth rates were low at week 6 (subjective rates were 23% and 19% for Nd:YAG and diode laser, respectively), most patients had significant regrowth at week 36 (subjective regrowth rate 91% for both long-pulsed Nd:YAG and diode lasers).
Diode 800 nm and Nd:YAG 1064 nm lasers are safe in laser-assisted hair removal in Chinese patients, and besides immediate pain, there was no other significant adverse effect. Most patients experienced regrowth 36 weeks after a single treatment. Further study is necessary to determine the long-term clinical efficacy and complications of laser-assisted hair removal with these systems in dark-skinned patients.
The aim was to investigate the efficacy, side effects, and the long-term results of a long pulsed Nd:YAG-Laser for hair removal in different hair colors and skin types.
We performed a prospective clinical study with 29 volunteers. Treatment was performed on the lower leg with a long pulsed Nd:YAG-Laser. Five test areas were treated 1-5 times in monthly intervals; one served as control. Follow-up investigations were performed at each session, and 3, 6, and 12 months after the last therapy. No depilatory treatment except shaving was allowed during the time of follow-up. Percentual hair loss, short- and long-term side effects, and pain during the treatment were evaluated.
After one month, a hair loss of greater than 50% was found in 44.9% of the areas treated once. With up to five treatments, this percentage increased up to 71.5%. One year after therapy, a greater than 50% hair reduction was still present in 40% of the five-treatment-areas and in 0% of the areas treated only once. There were no permanent side effects despite one small scar after a folliculitis.
The long pulsed Nd:YAG is suitable to remove hair for more than 12 months effectively, although 4-5 sessions are necessary for these results. Blond hair can also be removed, although much less effective. No lasting side effects could be seen. Darker skin types or tanned skin can also be treated without side effects. A cooling may be advisable due to the pain reported by the volunteers.
We present a new theory of selective thermal damage of non-uniformly pigmented structures in biological tissues. Spatial separation of the heavily pigmented areas and the target requires limitation of the pigment temperature and heat diffusion from the pigmented to the targeted areas.
A concept of selective target damage by heat diffusion is presented for three target geometries: planar, cylindrical, and spherical. An in vitro experiment is described in which the dependence of thermal damage on pulsewidth at constant fluence was evaluated.
The in vitro experiment showed that the size of the damage zone for similar hair follicles was pulsewidth-independent over a very broad range of pulsewidths (30-400 ms). We formulated a new theory (extended theory of photothermolysis) to interpret the experimental results.
Based on this new theory, the treatment pulsewidth for non-uniformly pigmented targets is significantly longer than the target thermal relaxation time (TRT). The theory provides new recommendations for photoepilation and photosclerotherapy parameters.
Effective hair removal continues to pose a challenge to the physician. The use of lasers represents a significant advance in epilation, but still requires further refinement. The long-pulsed Nd:YAG laser may offer advantages over other systems because of its significant depth of penetration and minimal absorption by epidermal melanin, but ideal parameters need to be determined.
To evaluate the efficacy of a long-pulsed Nd:YAG laser system and determine the optimal parameters for hair removal.
Twenty-two subjects were treated with a cryogen spray-cooled long-pulsed Nd:YAG laser. Four adjacent sites were assigned to each subject, where the following sets of parameters were utilized: 50 J/cm2 with a 25-msec pulse duration, 60 J/cm2 with a 50-msec pulse duration, 80 J/cm2 with a 50-msec pulse duration, and control. Hair counts were obtained immediately, 1 week, 1 month, and 3 months after treatment, and multivariate regression analysis was used to determine the significance of hair reduction. Acute reactions and adverse events were also evaluated.
Treatment at all three sets of parameters resulted in significant mean hair reductions immediately, at 1 week, and at 1 month (P <.001). At 3 months, the higher settings of 60 J/cm2 and 50 msec and 80 J/cm2 and 50 msec were statistically significant for reduced mean hair counts (P =.014, P =.042, respectively), while the lowest setting at 50 J/cm2 and 25 msec was not significant (P =.079). Patient and physician assessments suggested optimal hair reduction at the highest fluence (80 J/cm2) and longest pulse duration (50 msec). The most common acute reactions were pain during treatment, erythema, and perifollicular edema, all of which were more severe with higher fluences.
The long-pulsed Nd:YAG laser is a safe and effective method of hair removal. Increased fluence (60-80 J/cm2) and longer pulse duration (50 msec) settings were generally correlated with reduced hair counts and improved clinical outcome.
In the last years several lasers have proven their efficacy for hair removal. However, little is known about the efficacy of varying the spot size with those lasers.
To evaluate the long-term efficacy of hair removal using a diode laser with different spot sizes.
A long-pulsed diode laser (2 x 60 msec) was used. The spot size was 8 mm, 12 mm, or 14 mm. Twenty consenting volunteers were treated three times at regular intervals of 3 weeks. The ratio of the number of hairs in the treated area to an adjacent area left untreated (control) was referred to as regrowth.
One month after laser treatment, regrowth was 23% (8 mm), 12% (12 mm), and 13% (14 mm). After 3 months regrowth was 67% (8 mm), 54% (12 mm), and 55% (14 mm). Fifteen months after treatment 4 of 16 volunteers had a regrowth rate of less than 25%.
The results provide evidence for an effective and long-lasting growth delay of hairs using the long-pulsed diode laser. The use of large spot sizes improved the growth delay of hairs measured 1 month after treatment.
Hohenleutner Department of Dermatology, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany E-mail: kerstin.raff@klinik.uni-regensburg
- K Raff
- Ae
- M Landthaler
- Ae
K. Raff (&) AE M. Landthaler AE U. Hohenleutner Department of Dermatology, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany E-mail: kerstin.raff@klinik.uni-regensburg.de Tel.: +49-941-9449610
Laserlicht-Gewebe-Interaktionen Lasertherapie in der Dermatologie
- M Landthaler
- U Hohenleutner