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Tina S Alster - One of the best experts on this subject based on the ideXlab platform.
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treatment of exogenous ochronosis with a q switched Alexandrite 755 nm laser
Dermatologic Surgery, 2004Co-Authors: Supriya G Bellew, Tina S AlsterAbstract:Background. Exogenous ochronosis is a cutaneous disorder characterized by blue-black or slate-gray hyperpigmentation resulting from the prolonged use of certain topical agents, most commonly hydroquinones. It is notoriously difficult to treat. Objective. To report the effectiveness of a quality-switched (QS) 755-nm Alexandrite laser in treating hydroquinone-induced exogenous ochronosis. Methods. Hydroquinone-induced exogenous ochronosis in two patients was treated with a QS Alexandrite laser. The first patient received six treatments (average fluence=7.8 J/cm2) at 2-month intervals. The second patient received four treatments (average fluence=6.9 J/cm2) at 4-month intervals. Biopsies of lesional skin were obtained before and after laser treatment for histologic evaluation. Results. Significant lightening of the pigmented skin areas was achieved in both patients without scarring or textural changes. Decreased dermal pigmentation was observed on histologic examination of treated skin specimens. Conclusion. The QS Alexandrite laser can effectively treat exogenous ochronosis without untoward side effects.
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treatment of an amalgam tattoo with a q switched Alexandrite 755 nm laser
Dermatologic Surgery, 2002Co-Authors: Geeta Shah, Tina S AlsterAbstract:background. Amalgam tattoos result from deposition of metallic particles (eg, silver, mercury, copper, zinc, and tin) into the oral mucosa. Their clinical and histologic appearance is similar to that of decorative tatoos. objective. To describe the successful use of a Q-switched Alexandrite laser for removal of an amalgam tattoo. materials and methods. An amalgam tattoo on the buccal mucosa and gingiva was treated with a QS 755nm Alexandrite laser. Three treatments were delivered at 8-week time intervals (average fluence = 6.8 J/cm2). results. Significant lightening of the tattoo was achieved after each of the three treatments without adverse sequelae. conclusion. Q-switched Alexandrite laser irradiation can safely and effectively eradicate amalgam tattoos.
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long pulsed Alexandrite laser assisted hair removal at 5 10 and 20 millisecond pulse durations
Lasers in Surgery and Medicine, 1999Co-Authors: Christopher A Nanni, Tina S AlsterAbstract:Background Several laser systems with varying wavelengths, pulse durations, and energy fluences are currently utilized for hair removal. However, the ideal laser parameters and treatment candidates for photoepilation remain largely unknown. The medical literature lacks a wealth of experimental data to sufficiently document the long-term safety and efficacy of laser-assisted hair removal. This study examines the clinical efficacy and side effect profile of long-pulsed Alexandrite laser-assisted hair removal utilizing laser pulse durations of either 5, 10, or 20 milliseconds (ms). Study Design/Methods Laser-assisted hair removal was performed on 36 subjects with a long-pulsed Alexandrite laser. Areas of unwanted hair growth on the face, back, and legs were divided linearly into four 1 cm2 or 2 cm2 quadrants. Experimental regions included a control quadrant and three additional quadrants, which were treated with the Alexandrite laser using an average fluence of 18 J/cm2, with a 10 mm spot size at either a 5, 10, or 20 ms pulse duration. Hair counts and photographs were obtained before treatment, immediately following irradiation, 1 week and 1, 3, and 6 months postoperatively. Results All laser-treated quadrants displayed a significant delay in hair regrowth compared to control nontreated quadrants at postoperative week 1 and months 1 and 3. Hair counts were reduced by 66% at 1 month, 27% at 3 months, and 4% at 6 months. No significant differences in clinical efficacy or side effect profiles were observed between treatment quadrants, yet a trend towards less post-treatment erythema and hyperpigmentation was noted with the 20 ms pulse duration. Conclusions Equivalent long-term hair removal for up to 6 months was achieved with the long-pulsed Alexandrite laser at 5, 10, and 20 ms pulse durations at an average fluence of 18 J/cm2. Side effects were limited and transient. Lasers Surg. Med. 24:332–337, 1999. © 1999 Wiley-Liss, Inc.
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q switched Alexandrite laser treatment 755 nm of professional and amateur tattoos
Journal of The American Academy of Dermatology, 1995Co-Authors: Tina S AlsterAbstract:Abstract Background: Several laser techniques have been proposed for the removal of decorative tattoos. The lasers that have been used most successfully are Q-switched red or near-infrared systems because of their ability to target tattoo pigment selectively with minimal risk of scarring or permanent pigmentary changes. Objectives: The objectives of this study were to determine the clinical effectiveness of the newest Q-switched system, the Alexandrite laser, in removing amateur and professional tattoos and to observe side effects. Methods: Twenty-four multicolored professional tattoos and 18 blue-black amateur tattoos were treated with the Q-switched Alexandrite laser (755 nm, 100 nsec) at 2-month intervals until total clearing was achieved. The 510 nm pulsed dye laser was used to treat tattoos that contained red pigment. Results: Professional tattoos required an average of 8.5 Alexandrite laser treatments for total clearance, whereas only 4.6 treatments were necessary to remove amateur tattoos. Red tattoo pigment was successfully treated with an average of two 510 nm pulsed dye laser sessions. No scarring or long-standing pigmentary changes were seen in laser-irradiated skin. Conclusion: The Q-switched Alexandrite laser is highly effective in removing multicolored professional and amateur tattoos without adverse sequelae. The 510 nm pulsed dye laser was useful in eliminating red tattoo pigment.
Richard E. Fitzpatrick - One of the best experts on this subject based on the ideXlab platform.
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use of the q switched 755 nm Alexandrite laser to treat recalcitrant pigment after depigmentation therapy for vitiligo
Dermatologic Surgery, 2004Co-Authors: Richard E. FitzpatrickAbstract:Background. In patients with extensive vitiligo, depigmentation therapy is often preferred over attempts to restore skin color. Bleaching creams sometimes fail to permanently depigment the skin, leaving disfiguring pigmented patches. This recalcitrant pigmentation may be treated with Q-switched laser technology. Objective. The objective was use the Q-switched Alexandrite laser to treat recalcitrant pigmentation after unsuccessful attempts at total-body depigmentation for vitiligo. Methods. We have attempted to destroy the remaining melanin pigmentation in a 68-year-old woman with vitiligo by using selective photothermolysis from a Q-switched Alexandrite laser. Results. Excellent results were achieved after 10 treatment sessions, with no recurrence of pigment after 1 year of follow-up. Conclusion. The Q-switched Alexandrite laser was used successfully and safely in a vitiligo patient with recalcitrant pigmentation after unsuccessful depigmentation therapy and may prove useful in other such cases.
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comparison of the q switched Alexandrite nd yag and ruby lasers in treating blue black tattoos
Dermatologic Surgery, 1999Co-Authors: Mia L Leuenberger, Maria W Mulas, Tissa R Hata, Mitchel P. Goldman, Richard E. Fitzpatrick, Joop M GrevelinkAbstract:Background. A new generation of highly selective short-pulsed lasers has emerged in recent years for the treatment of tattoos. Several studies (including reports by the present investigators) have proven the efficacy of each of the three commercially available, FDA approved devices; namely, the Q-switched Alexandrite, Q-switched Nd:YAG and Q-switched ruby lasers. Considerable differences among the three have been reported in relation to the rate of clearing of the tattoo ink particles, tissue effects, beam profile, wound healing, and side effects. Objective. This study was primarily conducted to examine and compare the clinical response of patients with blue-black tattoos simultaneously treated with three different Q-switched lasers (Alexandrite, Nd:YAG, ruby) with a focus on the percentage of tattoo lightening/clearance and the occurrence or non-occurrence of pigmentary change as a side effect. Methods. A total of forty-two blue-black tattoos seen at two laser centers (Massachusetts General Hospital Dermatology Laser Center and Laser and Skin Surgery Center of La Jolla) were simultaneously treated with three types of Q-switched lasers: a Candela Q-switched Alexandrite laser (755nm 50-100 nanoseconds, 3.0mm spot size, 6-8 J/cm2); a Continuum Biomedical Q-switched Nd:YAG laser (1064nm, 10-20 nanoseconds, 3.0mm spot size, 5-10 J/cm2); and a Spectrum Q-switched ruby laser (694nm, 25-40 nanoseconds, 5.0mm spot size, 4-10 J/cm2). Paired t-tests and McNemar tests were used to compare the treatment outcome and pigmentation side effects between sites per tattoo, with each site representative of one of the three lasers. The statistical significance level was set at p < .05. Results. Overall, the Q-switched ruby laser had a significant difference in tattoo lightening versus the Q-switched Nd:YAG and Q-switched Alexandrite lasers. An increase in the number of treatments paralleled a statistically significant increase in tattoo clearance for all three Q-switched lasers. Conclusion. The Q-switched ruby laser had the highest clearance rate in blue-black tattoos and the highest incidence of longlasting hypopigmentation. The Nd:YAG had no incidence of hypopigmentation.
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tattoo removal using the Alexandrite laser
Archives of Dermatology, 1994Co-Authors: Richard E. Fitzpatrick, Mitchel P. GoldmanAbstract:Background: Until the recent development of the Q-switched lasers, it was not possible to remove tattoos without causing scarring, sometimes very disfiguring. Variations in wavelengths and pulse widths used may result in different clinical effectiveness or risks. The objective of this study was to determine the effectiveness of the Alexandrite laser in removing professional and amateur tattoo pigment without adverse tissue response. Results: We describe the clinical and histologic effects of the use of a new Q-switched laser for treatment of tattoos, the Alexandrite laser (wavelength, 755 nm; pulse width, 100 nanoseconds). The results of treatment of 17 patients with professional tattoos and eight patients with amateur tattoos are analyzed. Greater than 95% removal of tattoo pigment averaged 8.9 treatment sessions. Transient hypopigmentation occurred in approximately 50% of patients, and transient textural surface changes occurred in 12%. Conclusions: The Alexandrite laser is a safe and effective treatment modality for removal of black and blueblack tattoo pigment. (Arch Dermatol. 1994;130:1508-1514)
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use of the Alexandrite laser 755 nm 100 nsec for tattoo pigment removal in an animal model
Journal of The American Academy of Dermatology, 1993Co-Authors: Richard E. Fitzpatrick, Mitchel P. Goldman, Javier RuizesparzaAbstract:Background: All previous treatment modalities for the removal of tattoos, with the possible exception of the Q-switched ruby and YAG lasers, result in scarring. Objective: The purpose of this study was to investigate the use of a new laser that may remove tattoo pigment without leaving a scar. Methods: A Yucatan micropig was tattooed by a professional tattoo artist with black, blue, green, and red pigments. These tattoos were then treated with single overlapping pulses with the Alexandrite laser (wavelength 755 nm, pulse 100 nsec) and evaluated clinically and histologically. Comparison treatment with an argon laser (wavelength 488 nm, 514 nm, continuous-wave) and flashlamp-pumped dye laser (wavelength 585 nm, pulse 450 μsec) was performed as well for removal of red tattoo pigment. Results: The Alexandrite laser was found to be very effective in removal of professional and amateur black tattoo pigment, moderately effective in removal of blue and green pigment, and minimally effective in removal of red pigment. No scarring was seen clinically or histologically. Conclusion: The Alexandrite laser shows promise as a treatment modality for tattoo removal without scarring.
Michael J. Damzen - One of the best experts on this subject based on the ideXlab platform.
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Thermal and population induced lensing in Alexandrite lasers
Laser Resonators Microresonators and Beam Control XXII, 2020Co-Authors: Goronwy Tawy, Jian Wang, Michael J. DamzenAbstract:We present an overview of pump-induced lensing effects in end-pumped Alexandrite lasers. The dioptric lens power is measured for a diode pumped Alexandrite laser using a Shack-Hartmann wavefront sensor under both non-lasing and lasing conditions. Under non-lasing conditions, the lens dioptric power is measured for two pump sizes and in both cases is found to be nearly linear with respect to the absorbed pump power. Under lasing conditions the lens dioptric power is up to 60% weaker. Good agreement is found between the non lasing and lasing experimental results using a model based on a combined lens consisting of a thermal lens, and a population lens arising from the electronic component of the refractive index. Fitting parameters using an analytical model for the two pump sizes are also found to be consistent. Values for the difference in excited to ground state polarizability are obtained and found to be consistent with prior measurements for Alexandrite and other Chromium-doped gain media.
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pump induced lensing effects in diode pumped Alexandrite lasers
Optics Express, 2019Co-Authors: Goronwy Tawy, Jian Wang, Michael J. DamzenAbstract:It is essential to understand the pump-induced lensing and aberration effects in solid-state lasers, such as Alexandrite, since these set limits on laser power scaling whilst maintaining high spatial TEM00 beam quality. In this work, we present direct wavefront measurements of pump-induced lensing and spherical aberration using a Shack-Hartmann wavefront sensor, for the first time, in a diode-pumped Alexandrite laser, and under both non-lasing and lasing conditions. The lens dioptric power is found to be weakly sub-linear with respect to the absorbed pump power, and under lasing, the lensing power is observed to decrease to 60 % of its non-lasing value. The results are inconsistent with a thermal lens model but a fuller theoretical formulation is made of a combined thermal and population lens model giving good quantitative agreement to the observed pump power dependence of the induced-lensing under non-lasing conditions and the reduced lensing under lasing conditions. The deduced value for the difference in excited to ground state polarizability is consistent with prior measurement estimates for other chromium-doped gain media. The finding of this paper provide new insight into pump-induced lensing in Alexandrite and also provides a basis for a fast saturable population lens mechanism to account for self-Q-switching observed recently in Alexandrite laser systems.
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Population Lensing in Alexandrite Lasers
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO Europe-EQEC), 2019Co-Authors: Goronwy Tawy, Jian Wang, Michael J. DamzenAbstract:Alexandrite (Cr3+:BeAl2O4) is a vibronic laser at 701-858 nm. Its excellent thermo-mechanical properties and high energy storage make it an ideal high power and high energy Q-switched source with recent development in mJ-level red-diode-pumped Alexandrite oscillators and amplifiers [1-3]. Further power scaling of these systems is limited by thermal lensing which has yet to be addressed in great detail. In this work we present experimental and finite element analysis (FEA) results on the investigation of thermal lensing in a red-diode-pumped Alexandrite laser. Differences in the thermal lensing power for non-lasing and lasing conditions are attributed to a `population lens' effect. In a separate study stable self-Q-switching (SQS) is observed in an Alexandrite laser cavity containing only the gain medium where the SQS loss mechanism is attributed to the population lens.
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tunable dual wavelength and self q switched Alexandrite laser using crystal birefringence control
Optics Express, 2019Co-Authors: Goronwy Tawy, Michael J. DamzenAbstract:We present a red-diode-pumped Alexandrite laser with continuous wavelength tunability, dual wavelength and self-Q-switching in an ultra-compact resonator containing only the gain medium. Wavelength tuning is obtained by varying the geometrical path length and birefringence by tilting a Brewster-cut Alexandrite crystal. Two crystals from independent suppliers are used to demonstrate and compare the performance. Wavelength tuning between 750 and 764 nm is demonstrated in the first crystal and between 747 and 768 nm in the second crystal. Stable dual wavelength operation is also obtained in both crystals with wavelength separation determined by the crystal free spectral range. Temperature tuning was also demonstrated to provide finer wavelength tuning at a rate of −0.07 nm K −1. Over a narrow tuning range, stable self-Q-switching is observed with a pulse duration of 660 ns at 135 kHz, which we believe is the highest Q-switched pulse rate in Alexandrite to date. Theoretical modelling is performed showing good agreement with the wavelength tuning and dual wavelength results.
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compact non astigmatic Alexandrite ring laser with unidirectional single longitudinal mode operation
European Quantum Electronics Conference, 2019Co-Authors: Juna Sathian, Goronwy Tawy, A Minassian, Xin Sheng, Michael J. DamzenAbstract:Progress in single frequency and precise wavelength tunable lasers are essential to address future demands in high resolution spectroscopy, metrology and quantum technology systems. Alexandrite lasers with wide tunability in near-IR spectral region when pumped by low cost red diodes provide a good prospect as a cost effective precision laser source. This was demonstrated in our earlier work [1] using a tunable single-frequency bow-tie cavity with Brewster-cut Alexandrite crystal. The astigmatism of the Brewster cut gain medium and need for angled curved mirrors for astigmatic compensation, whilst being well established [2,3] also places some complexity on the design and can be compromised by astigmatic thermal lensing [1]. Here we report the investigation and successful operation of a non-astigmatic compact design of a unidirectional wavelength tunable Alexandrite ring laser with single frequency operation.
Mitchel P. Goldman - One of the best experts on this subject based on the ideXlab platform.
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analysis of incidence of bulla formation after tattoo treatment using the combination of the picosecond Alexandrite laser and fractionated co2 ablation
Dermatologic Surgery, 2015Co-Authors: Sonoa Au, Ana Marie Liolios, Mitchel P. GoldmanAbstract:BACKGROUND: The picosecond Alexandrite laser has shown increased efficacy in tattoo removal in comparison to Q-switched lasers. However, bulla formation is a well-known and expected side effect of this novel treatment and causes patient discomfort. OBJECTIVE: To analyze the incidence of bulla formation after tattoo treatment using the combination of the picosecond Alexandrite laser and fractionated CO2 ablation. MATERIALS AND METHODS: This is a retrospective chart review to determine the incidence of bulla formation after laser tattoo removal in 95 patients who were treated with either with the picosecond Alexandrite laser alone or in combination with fractional CO2 ablation. RESULTS: Twenty-six patients (32%) treated with the picosecond laser alone experienced blistering, whereas none of the patients treated with the combination of the picosecond laser and fractionated CO2 ablation experienced blistering. The difference in incidence of bulla formation between the 2 groups was found to be statistically significant (p < .05). CONCLUSION: This study shows a significant decrease in bulla formation associated with tattoo treatment when fractionated CO2 ablation is added to the picosecond Alexandrite laser, which is consistent with observations from a previous case series. This is important because decreasing extensive blistering likely results in increased patient satisfaction and willingness to return for future treatments.
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comparative evaluation of long pulse Alexandrite and long pulse nd yag laser systems used individually and in combination for axillary hair removal
Dermatologic Surgery, 2008Co-Authors: Jane G Khoury, Raminder Saluja, Mitchel P. GoldmanAbstract:BACKGROUND The 755-nm Alexandrite and the 1,064-nm Nd:YAG lasers are both utilized for hair removal. Advances in laser technology have led to the development of dual-wavelength treatment for increased efficacy. OBJECTIVE The objective was to evaluate the safety and efficacy of combining 755- and 1,064-nm wavelengths for axillary hair removal. METHODS Twenty patients received three treatments at 4- to 6-week intervals in four axillary quadrants. The left upper axilla was treated with the Alexandrite laser, the left lower axilla with the Nd:YAG laser, the right upper axilla with combination Alexandrite and Nd:YAG laser, and the right lower quadrant with the diode laser. At 1- and 2-month follow-up visits, subjects completed questionnaires and were assessed for percentage of hair reduction. RESULTS Eighteen subjects completed the study. The greatest reduction was seen with the Alexandrite laser at 70.3% and combination of Alexandrite and Nd:YAG laser at 67.1%. The diode laser was less efficacious at 59.7% and the Nd:YAG laser had the least improvement with 47.4% reduction. Subjects found the Alexandrite and diode lasers to be the most tolerable and the Nd:YAG and combination treatment to be the most painful. CONCLUSION Combination treatment of Alexandrite and Nd:YAG lasers provides no added benefit over the Alexandrite laser alone.
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comparison of the q switched Alexandrite nd yag and ruby lasers in treating blue black tattoos
Dermatologic Surgery, 1999Co-Authors: Mia L Leuenberger, Maria W Mulas, Tissa R Hata, Mitchel P. Goldman, Richard E. Fitzpatrick, Joop M GrevelinkAbstract:Background. A new generation of highly selective short-pulsed lasers has emerged in recent years for the treatment of tattoos. Several studies (including reports by the present investigators) have proven the efficacy of each of the three commercially available, FDA approved devices; namely, the Q-switched Alexandrite, Q-switched Nd:YAG and Q-switched ruby lasers. Considerable differences among the three have been reported in relation to the rate of clearing of the tattoo ink particles, tissue effects, beam profile, wound healing, and side effects. Objective. This study was primarily conducted to examine and compare the clinical response of patients with blue-black tattoos simultaneously treated with three different Q-switched lasers (Alexandrite, Nd:YAG, ruby) with a focus on the percentage of tattoo lightening/clearance and the occurrence or non-occurrence of pigmentary change as a side effect. Methods. A total of forty-two blue-black tattoos seen at two laser centers (Massachusetts General Hospital Dermatology Laser Center and Laser and Skin Surgery Center of La Jolla) were simultaneously treated with three types of Q-switched lasers: a Candela Q-switched Alexandrite laser (755nm 50-100 nanoseconds, 3.0mm spot size, 6-8 J/cm2); a Continuum Biomedical Q-switched Nd:YAG laser (1064nm, 10-20 nanoseconds, 3.0mm spot size, 5-10 J/cm2); and a Spectrum Q-switched ruby laser (694nm, 25-40 nanoseconds, 5.0mm spot size, 4-10 J/cm2). Paired t-tests and McNemar tests were used to compare the treatment outcome and pigmentation side effects between sites per tattoo, with each site representative of one of the three lasers. The statistical significance level was set at p < .05. Results. Overall, the Q-switched ruby laser had a significant difference in tattoo lightening versus the Q-switched Nd:YAG and Q-switched Alexandrite lasers. An increase in the number of treatments paralleled a statistically significant increase in tattoo clearance for all three Q-switched lasers. Conclusion. The Q-switched ruby laser had the highest clearance rate in blue-black tattoos and the highest incidence of longlasting hypopigmentation. The Nd:YAG had no incidence of hypopigmentation.
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tattoo removal using the Alexandrite laser
Archives of Dermatology, 1994Co-Authors: Richard E. Fitzpatrick, Mitchel P. GoldmanAbstract:Background: Until the recent development of the Q-switched lasers, it was not possible to remove tattoos without causing scarring, sometimes very disfiguring. Variations in wavelengths and pulse widths used may result in different clinical effectiveness or risks. The objective of this study was to determine the effectiveness of the Alexandrite laser in removing professional and amateur tattoo pigment without adverse tissue response. Results: We describe the clinical and histologic effects of the use of a new Q-switched laser for treatment of tattoos, the Alexandrite laser (wavelength, 755 nm; pulse width, 100 nanoseconds). The results of treatment of 17 patients with professional tattoos and eight patients with amateur tattoos are analyzed. Greater than 95% removal of tattoo pigment averaged 8.9 treatment sessions. Transient hypopigmentation occurred in approximately 50% of patients, and transient textural surface changes occurred in 12%. Conclusions: The Alexandrite laser is a safe and effective treatment modality for removal of black and blueblack tattoo pigment. (Arch Dermatol. 1994;130:1508-1514)
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use of the Alexandrite laser 755 nm 100 nsec for tattoo pigment removal in an animal model
Journal of The American Academy of Dermatology, 1993Co-Authors: Richard E. Fitzpatrick, Mitchel P. Goldman, Javier RuizesparzaAbstract:Background: All previous treatment modalities for the removal of tattoos, with the possible exception of the Q-switched ruby and YAG lasers, result in scarring. Objective: The purpose of this study was to investigate the use of a new laser that may remove tattoo pigment without leaving a scar. Methods: A Yucatan micropig was tattooed by a professional tattoo artist with black, blue, green, and red pigments. These tattoos were then treated with single overlapping pulses with the Alexandrite laser (wavelength 755 nm, pulse 100 nsec) and evaluated clinically and histologically. Comparison treatment with an argon laser (wavelength 488 nm, 514 nm, continuous-wave) and flashlamp-pumped dye laser (wavelength 585 nm, pulse 450 μsec) was performed as well for removal of red tattoo pigment. Results: The Alexandrite laser was found to be very effective in removal of professional and amateur black tattoo pigment, moderately effective in removal of blue and green pigment, and minimally effective in removal of red pigment. No scarring was seen clinically or histologically. Conclusion: The Alexandrite laser shows promise as a treatment modality for tattoo removal without scarring.
Henry H Chan - One of the best experts on this subject based on the ideXlab platform.
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a retrospective analysis on the management of pigmented lesions using a picosecond 755 nm Alexandrite laser in asians
Lasers in Surgery and Medicine, 2016Co-Authors: Johnny C Y Chan, Samantha Y Shek, Taro Kono, C K Yeung, Henry H ChanAbstract:Background and objectives Photo-aging in Chinese often presents with benign pigmentary lesions. Q-switched lasers for pigmentary lesions in Asians had reported a risk of post-inflammatory hyperpigmentation (PIH) up to 25%. Longer pulse widths in the millisecond domains were advocated with reduced risk of PIH. Recently, picosecond lasers of various wavelengths were introduced with proven efficacy in tattoo removal. The objective of this study is to assess the efficacy and safety of a novel picosecond 755-nm Alexandrite laser for the treatment of benign pigmented lesions in Asians retrospectively. Methods A list of all patients who received picosecond 755-nm Alexandrite laser treatment at a private dermatology center in Hong Kong was included. Those who had any other laser or topical treatment during the period of picosecond laser treatment were excluded. The age, skin phototype, type of pigmentary lesion, number of treatments performed was recorded. The baseline and most recent standardized photographs were assessed by trained physicians for comparison. A score of 0–4, representing poor 0–24%, fair 25–49%, good 50–74%, excellent 75–95%, and complete 95%+ improvement was given. Adverse events associated with the laser treatment were also recorded. All patients were followed up until 6 months after the last laser session. Results A total of 13 subjects were included in the present study. The number of treatment sessions received ranged from one to seven. The benign pigmentary lesions consist of Nevus of Ota, cafe-au-lait patches, lentigines, Becker's nevus, Hori's macules, and nevus spilus. Among patients with Nevus of Ota, one patient achieved complete clearance after four treatments and two other patients had excellent clearance after three and four sessions, respectively. Patients with cafe-au-lait had fair to good clearance after one to seven treatment sessions. One patient who has Hori's macules was resistant to laser treatments and a fair response was achieved after eight treatments. In the present series, two patients (4.8%) developed transient hypopigmentation, which had improved upon subsequent follow-up in both cases and none had post-inflammatory hyperpigmentation. Conclusions The novel picosecond 755-nm alexandrine laser is effective for the treatment of benign pigmentary lesions in Chinese, especially for the clearance of Nevus of Ota. Picosecond laser appears to be associated with a much lower risk of PIH for treatment of pigmentary lesions in Asians. Lasers Surg. Med. 48:23–29, 2016. © 2015 Wiley Periodicals, Inc.
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a comparison of q switched and long pulsed Alexandrite laser for the treatment of freckles and lentigines in oriental patients
Lasers in Surgery and Medicine, 2011Co-Authors: Stephanie G Y Ho, C K Yeung, Henry H Chan, Npy Chan, Syn ShekAbstract:Background Q-switched (QS) lasers are effective in the treatment of freckles and lentigines in Type I and II skin, with minimal adverse effects. Long pulsed (LP) lasers have been proposed to be more suitable for treatment of darker skin types. Objectives To investigate the efficacy and adverse effects of using QS or LP Alexandrite laser for the treatment of freckles and lentigines in Oriental patients. Methods A prospective split-face study of 20 Chinese patients who were randomly assigned to undergo a single QS (50 nanosecond) or LP (100 microseconds) laser treatment to either side of their face was carried out. Two blinded physicians assessed clinical efficacy using visual analogue scales of pre- and post-treatment photographs. Subjective assessment was evaluated using questionnaires which detailed the degree of pain, erythema and edema sustained during treatment, and improvement and satisfaction levels at 4, 8, and 12 weeks. Results There was statistically significant improvement in pigmentation (P < 0.05) in both groups throughout the study, with no statistical difference found between the groups. Postinflammatory hyperpigmentation was more frequently found after QS treatment (22%), compared to LP treatment (6%). Majority of patients reported moderate to marked improvement in pigmentation throughout the study with both pulse widths, and correspondingly high levels of satisfaction rates. More severe pain, erythema and edema were experienced during QS Alexandrite treatment. Conclusion LP Alexandrite is quick and effective, and carries a lower risk of adverse effects than QS Alexandrite, for the removal of freckles and lentigines in darker skin types. Lasers Surg. Med. 42:108–113, 2011 © 2011 Wiley-Liss, Inc.
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a retrospective study on the efficacy and complications of q switched Alexandrite laser in the treatment of acquired bilateral nevus of ota like macules
Dermatologic Surgery, 2001Co-Authors: D Wong, W S Ho, Henry H ChanAbstract:Background. Acquired bilateral nevus of Ota-like macules (ABNOM), or Hori's macules, is a common Asian condition that is characterized by bluish hyperpigmentation in the bilateral malar regions. Unlike nevus of Ota, ABNOM is an acquired condition that often develops after 20 years of age and involves both sides of the face, but there is no mucosal involvement. Recently Q-switched (QS) 1064 nm Nd:YAG lasers have been effective in clearing this condition. The effectiveness of QS Alexandrite lasers has not yet been studied. Objective. To retrospectively assess the efficacy and complications of QS Alexandrite lasers in the treatment of ABNOM. Methods. Thirty-two Chinese women with ABNOM ranging in age from 28 to 66 years were involved in the study. All underwent QS Alexandrite laser treatment (755 nm, spot size 3 mm, 8 J/cm2). Topical hydroquinone and tretinoin cream were given to those with hyperpigmentation after the laser surgery. Clinical photographs were taken before and after laser surgery and assessed by two independent observers. The degree of clearing was scored and complications, including hypopigmentation, hyperpigmentation, scarring, and erythema, were assessed. Results. The mean number of treatment sessions was 7 (range 2–11) and the mean treatment interval was 33 days. Both observers identified more than 80% of the patients as having more than a 50% degree of clearing, and complete clearance was seen in more than 28% of patients. Although most patients had postlaser hyperpigmentation and were on depigmentary regimes, the hyperpigmentation was seen in only 12.5% of the patients during photographic evaluation. Hypopigmentation was seen in 50% of patients and erythema in 41%. Conclusion. QS Alexandrite appears to be effective in the treatment of ABNOM. Postoperative pigmentary changes were frequent and the use of topical depigmentary agents was necessary to achieve a satisfactory result. Transient hypopigmentation risk was high, affecting up to 50% of the patients. Further study is warranted to compare the efficacy and complications of different laser systems in the treatment of this condition.