Q开关激光治疗双侧面部获得性太田痣样斑287例疗效分析

目的：比较Q开关紫翠宝石755nm激光、Nd：YAG1064nm激光和倍频Nd：YAG532nm激光对双侧获得性太田痣样斑的治疗效果和副作用。方法：运用Q开关紫翠宝石755nm激光、Nd：YAG1064nm激光和倍频Nd：YAG532nm激光分别对287例患者进行治疗。结果：经过1～13次治疗后,痊愈140例,显效66例,有效59例,无效22例,总有效率71.8%,总治愈率48.8%。倍频Nd：YAG532nm激光治疗起效快而副反应明显,Q开关紫翠宝石755nm激光和Nd：YAG1064nm激光起效慢但副反应轻微。结论：三种Q开关激光均能有效治疗双侧获得性太田痣样斑,长程低能量的Q开关紫翠宝石755nm激光和Nd：YAG1064nm激光因副反应轻微更适合美容患者的需要。     

Clinical,histologic, and ultrastructural evaluation of tattoos treated with three laser systems

We examined the response of tattoo pigments treated with three commercially available lasers: Q-switched ruby, Q-Switched neodynium:yttrium, aluminum, garnet (Nd:YAG), and the alexandrite. Tattoos applied to hairless guinea pigs and treated with the aforementioned lasers were evaluated clinically, histologically, and ultrastructurally. Clinical evaluation showed red brown, dark brown, and orange pigment responded best to the Nd:YAG laser (1064 nm). The alexandrite laser was most effective for removing blue and green pigment, the Q-switched ruby laser was most effective for removing purple and violet pigment, and the NdYAG laser (532 nm) removed red pigment the best. Black pig ment was lightened equally with the Nd:YAG laser (1064 nm) and (532 nm) and the alexandrite laser (755 nm). No clinical scarring was observed; however, some colors turned black after treatment. Histologic and ultrastructural examination showed epidermal and dermal damage to be most evident after treatment with the Nd:YAG laser. Our study shows that certain tattoo pigments respond better to different laser systems. © 1994 WiIey-Liss, Inc.     

Successful treatment of treatment-resistant laser-induced pigment darkening of a cosmetic tattoo

BACKGROUND AND OBJECTIVE: Cosmetic tattoo removal has a reported risk of immediate pigment darkening when treated with a high energy, nanosecond pulsed-laser system. Surgical treatment options for this reaction are limited and carry significant risk of scarring and permanent pigment alterations. This report describes the response of a resistant Q-switched ruby laser-induced cosmetic tattoo ink darkening to multiple treatments with the Q-switched alexandrite laser and Q-switch Nd:YAG laser and textural improvement with the UltraPulse CO(2) laser. STUDY DESIGN/MATERIALS AND METHODS: A woman with Q-switched ruby laser-induced pigment darkening of a cosmetic tattoo of the upper lip resistant to four further treatments with the ruby laser and two chemical peels received a total of 26 treatments with the Q-switched alexandrite and Nd:YAG lasers and a single treatment with the UltraPulse CO(2) laser, most treatments being done at monthly intervals. RESULTS: Treatment of the affected areas with the Q-switched alexandrite and Nd:YAG lasers resulted in complete clearing of the pigment without scarring, but revealed some preexisting textural changes. Use of the UltraPulse CO(2) laser smoothed the surface irregularities. CONCLUSION: The Q-switched pigment lasers are a useful modality for treating this pigment darkening reaction. As in this case, multiple treatment sessions with the laser may be necessary but the pigment can be expected to clear eventually without scarring. Any textural changes may be blended with the UltraPulse CO(2) laser with further improvement.     

Hair Removal Using Topical Suspension-Assisted Q-Switched Nd:YAG and Long-Pulsed Alexandrite Lasers: A Comparative Study

Background. The use of lasers for removal of unwanted hair has been shown to be effective in temporarily controlling hair growth. Several lasers are currently utilized for this purpose.
Objective. This study evaluates the short-term effectiveness and discomfort levels of the long-pulsed alexandrite laser and the topical suspension-assisted Q-switched Nd:YAG laser in a side-by-side comparison.
Methods. Fifteen subjects were treated in the bilateral hair-bearing axilla, using one treatment with the alexandrite laser for the right and two treatments with the topical suspension-assisted Nd:YAG laser for the left. Reduction in hair regrowth was measured at 2 and 3 months following the first treatment by comparing the terminal hair count to the baseline values. Patients rated their pain on a scale of 0–10 immediately following the first treatment at each site.
Results. The mean percentage reduction in hair regrowth 2 months following alexandrite laser treatment was 55% and 73% for the Nd:YAG laser-treated regions. After 3 months, alexandrite laser-treated patients showed a reduction of 19%, while Nd:YAG laser-treated patients showed a 27% reduction. Patients reported average pain values of 8 and 4 for the long-pulsed alexandrite and Nd:YAG laser sites, respectively. All differences were significant.
Conclusion. While the design of this study makes it difficult to compare the relative effectiveness of the lasers, both systems evaluated were shown to delay hair growth and provide patients with a satisfactory treatment.     

Comparative Evaluation of Long-Pulse Alexandrite and Long-Pulse Nd:YAG Laser Systems Used Individually and in Combination for Axillary Hair Removal

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.     

Lasers for tattoo removal: a review

Tattoos have existed and have been used as an expression of art by man for ages—and so have the techniques to remove them. Lasers based on the principle of selective photothermolysis are now being used to remove black as well as colorful tattoos with varying successes. The commonly used lasers for tattoo removal are the Q-switched 694-nm ruby laser, the Q-switched 755-nm alexandrite laser, the 1,064-nm Nd:YAG laser, and the 532-nm Nd:YAG laser. Newer techniques and methods are evolving in tattoo removal with lasers. Choosing the right laser for the right tattoo color is necessary for a successful outcome. Our review aims to understand the principles of laser tattoo removal and their applications for different types and colors of tattoos. The review also highlights the complications that can occur such as dyspigmentation, allergic reactions, epidermal debris, ink darkening, and so on, in this process and how to prevent them.     

Meta-analysis of hair removal laser trials

Traditional hair-removal techniques have included shaving, waxing, chemical depilation, and electrolysis. All of these methods result in temporary hair removal. The theory of selective photo thermolysis led to the development of a variety of different laser systems. These lasers range from the short end of spectrum, with the 694-nm ruby laser, to the middle, with the 755-nm alexandrite and 810-nm diode lasers, and to the long end with the 1,064-nm Nd:YAG laser. We made a systematic review on the clinical trials with use of various laser sources for hair removal, so all clinical trials related to hair removal lasers in 1998–2003 were considered after elimination of heterogenite sources in data store. Trial results were synthetized on the basis of kind of laser. Our study clarified that hair reduction at least 6 months after the last treatment and hair reductions were 57.5, 42.3, 54.7, and 52.8% after three sessions for diode, Nd:YAG, alexandrite and ruby, respectively. We compared the result with use of analysis of variance method (Scheffes) and double comparison with use of Student’s t test. Our results clarified that diode laser is the most effective, and Nd:YAG has the least effect of hair removal.It seems that diode and alexandrite lasers are proper for hair removal, but as we need high fluence in the darker skin types and this is accompanied with higher complications, diode is advised for lighter skin, and we advised alexandrite laser for darker skin types.     

High-speed photographic evaluation of endoscopic lithotripsy devices

Summary Shock-wave generation and bubble formation occurring during endoscopic lithotripsy were studied using high-speed photography for various devices: a pulsed-dye laser, a Q-switched Nd: YAG lase and an electrohydraulic (EHL) apparatus. The three devices investigated generated gas bubbles that rapidly expanded and decayed. The maximal size of these bubbles was 5–8 mm for the pulsed-dye laser, 6 mm for the Q-switched Nd: YAG laser and up to 14 mm for the EHL device. The bubble size appeared to be governed mainly by the energy per pulse delivered by the lithotripsy device. The shock-wave pattern depended strongly on the type of device used; the 25-ns Q-switched Nd: YAG laser pulse generated a single pressure step, whereas the 1.5-s pulsed-dye laser produced a train of shock fronts.     

Holmium:YAG laser lithotripsy: A dominant photothermal ablative mechanism with chemical decomposition of urinary calculi.

BACKGROUND AND OBJECTIVE: Evidence is presented that the fragmentation process of long-pulse Holmium:YAG (Ho:YAG) lithotripsy is governed by photothermal decomposition of the calculi rather than photomechanical or photoacoustical mechanisms as is widely thought. The clinical Ho:YAG laser lithotriptor (2.12 microm, 250 micros) operates in the free-running mode, producing pulse durations much longer than the time required for a sound wave to propagate beyond the optical penetration depth of this wavelength in water. Hence, it is unlikely that shock waves are produced during bubble formation. In addition, the vapor bubble induced by this laser is not spherical. Thus the magnitude of the pressure wave produced at cavitation collapse does not contribute significantly to lithotripsy. STUDY DESIGN/MATERIALS AND METHODS: A fast-flash photography setup was used to capture the dynamics of urinary calculus fragmentation at various delay times following the onset of the Ho:YAG laser pulse. These images were concurrently correlated with pressure measurements obtained with a piezoelectric polyvinylidene-fluoride needle-hydrophone. Stone mass-loss measurements for ablation of urinary calculi (1) in air (dehydrated and hydrated) and in water, and (2) at pre-cooled and at room temperatures were compared. Chemical and composition analyses were performed on the ablation products of several types of Ho:YAG laser irradiated urinary calculi, including calcium oxalate monohydrate (COM), calcium hydrogen phosphate dihydrate (CHPD), magnesium ammonium phosphate hexahydrate (MAPH), cystine, and uric acid calculi. RESULTS: When the optical fiber was placed perpendicularly in contact with the surface of the target, fast-flash photography provided visual evidence that ablation occurred approximately 50 micros after the initiation of the Ho:YAG laser pulse (250-350 micros duration; 375-400 mJ per pulse), long before the collapse of the cavitation bubble. The measured peak acoustical pressure upon cavitation collapse was negligible (< 2 bars), indicating that photomechanical forces were not responsible for the observed fragmentation process. When the fiber was placed in parallel to the calculus surface, the pressure peaks occurring at the collapse of the cavitation were on the order of 20 bars, but no fragmentation occurred. Regardless of fiber orientation, no shock waves were recorded at the beginning of bubble formation. Ablation of COM calculi (a total of 150 J; 0.5 J per pulse at an 8-Hz repetition rate) revealed different Ho:YAG efficiencies for dehydrated calculus, hydrated calculus, and submerged calculus. COM and cystine calculi, pre-cooled at -80 degrees C and then placed in water, yielded lower mass-loss during ablation (20 J, 1.0 J per pulse) compared to the mass-loss of calculi at room temperature. Chemical analyses of the ablated calculi revealed products resulting from thermal decomposition. Calcium carbonate was found in samples composed of COM calculi; calcium pyrophosphate was found in CHPD samples; free sulfur and cysteine were discovered in samples composed of cystine samples; and cyanide was found in samples of uric acid calculi. CONCLUSION: These experimental results provide convincing evidence that long-pulse Ho:YAG laser lithotripsy causes chemical decomposition of urinary calculi as a consequence of a dominant photothermal mechanism.     

New approaches to the treatment of vascular lesions

BACKGROUND AND OBJECTIVE: The pulsed dye laser was developed based on the concept of selective photothermolysis. By using a wavelength of light well absorbed by the target and pulse duration short enough to spatially confine thermal injury, specific vascular injury could be produced. STUDY DESIGN/MATERIALS AND METHODS: Although the pulsed dye laser revolutionized the treatment of port wine stains (PWS) and a variety of other vascular lesions, the ideal thermal relaxation time for the vessels in PWS is actually 1-10 ms, not 450 micros of the original pulsed dye laser machines. These original theoretical calculations recently have been proven correct in a study that used both an animal vessel model and in human PWS. RESULTS: Longer wavelengths of light, within the visible spectrum, penetrate more deeply into the skin and are more suitable for deeper vessels, whereas longer pulse durations are required for larger caliber vessels. CONCLUSION: A variety of lasers recently have been developed for the treatment of vascular lesions which incorporate these concepts into their design, including pulsed dye lasers at 1.5 ms, a filtered flash-lamp pulsed light source with pulse durations of 1-20 ms, several 532-nm pulsed lasers with pulse durations of 1 ms to as high as 100 ms, long pulsed alexandrite lasers at 755 nm with pulse durations up to 20 ms, pulsed diode lasers in the 800 to 900 nm range, and long pulsed 1064 Nd:YAG sources.     

An In Vivo Trial Comparing the Clinical Efficacy and Complications of Q-Switched 755 nm Alexandrite and Q-Switched 1064 nm Nd:YAG Lasers in the Treatment of Nevus of Ota

BACKGROUND: Q-switched 755 nm alexandrite (QS alex) and Q-switched 1064 nm Nd:YAG lasers are effective in the treatment of nevus of Ota. Our previous in vivo study indicated that patients better tolerate QS alex than QS 1064 nm Nd:YAG laser. However, in terms of clinical efficacy and long-term complications, the study did not indicate which laser is superior. Although both machines may appear to be similar in effectiveness, the low number of treatment sessions may contribute to this apparent lack of difference. OBJECTIVE: The aim of this study was to compare the clinical efficacy and complications of QS 755 nm alex and QS 1064 nm Nd:YAG lasers in the treatment of nevus of Ota after three or more treatment sessions. METHOD: Forty patients were recruited for this study and all had received three or more laser treatment sessions with an interval of at least 2 months between each. Half of the lesion was treated with QS alex and the other half with QS 1064 nm Nd:YAG laser. The degree of lightening was assessed subjectively by the patient using a visual analog scale and objectively by two independent clinicians. Patients were called back to be examined for evidence of complications. RESULTS: In terms of subjective degree of lightening, QS 1064 nm Nd:YAG laser was found to be significantly more efficacious than QS alex (P = 0.018). Both clinicians also found QS 1064 nm Nd:YAG laser to be more effective, but statistical significance was only detected in one, not both of their scores (P = 0.005 and 0.414 for observers 1 and 2, respectively). More patients that received QS Alex developed complications (4 for QS alex and 2 for QS Nd:YAG), but the difference was not statistically significant. CONCLUSION: QS 1064 nm Nd:YAG laser appears to be more effective than QS alex in the lightening of nevus of Ota after three or more laser treatment sessions. However, the majority (55%) of the patients reported no differences in results between the two lasers, and only one of the two observers noted statistically significant improvement of QS 1064 nm Nd:YAG over QS alex.     

The effects of laser irradiation on <Emphasis Type="Italic">Trichophyton rubrum</Emphasis> growth

The effects of various laser wavelengths and fluences on the fungal isolate, Trichophyton rubrum, were examined in vitro. Standard-size isolates of T. rubrum were irradiated by using various laser systems. Colony areas were compared for growth inhibition on days 1, 3, and 6 after laser irradiation. Statistically significant growth inhibition of T. rubrum was detected in colonies treated with the 1,064-nm Q-switched Nd:YAG laser at 4 and 8 J/cm² and 532-nm Q-switched Nd:YAG laser at 8 J/cm². Q-switched Nd:YAG laser at 532- and 1,064-nm wavelengths produced significant inhibitory effect upon the fungal isolate T. rubrum in this in vitro study. However, more in vitro and in vivo studies are necessary to investigate if lasers would have a potential use in the treatment of fungal infections of skin and its adnexa.     

Areolar Cosmetic Tattoo Ink Darkening: A Complication of Q-Switched Alexandrite Laser Treatment

BACKGROUND AND OBJECTIVE: Medical tattooing of the areola is widely performed in Korea. However, cosmetic tattoos containing flesh-tone, purple-red, and yellow dyes are sometimes resistant to Q-switched laser and may even become darker. METHOD: Two Korean women in their 30s who had a mastectomy got light brown to red areolar medical tattoos but they were not satisfied with the shape and size of the tattoos. They underwent Q-switched alexandrite laser treatment with a 3 mm collimated beam at fluences of 7.5-8 J/cm2 in order to trim the irregular contour and reduce the diameter of the tattoos. RESULTS: Within 5 minutes a dark gray to black discoloration of the treated area was evident and remained dark for 6 weeks. Improvement was not noted after two further Q-switched Nd:YAG laser treatments. CONCLUSION: Medical areolar tattoos should be approached with extra caution when attempting their removal with high-energy pulsed lasers such as Q-switched alexandrite laser and a small test site should be performed prior to treatment.     

Laser Hair Removal: Comparison of Long-Pulsed Nd:YAG, Long-Pulsed Alexandrite, and Long-Pulsed Diode Lasers

Background. Advances in laser technology over the past several years have led to the development of numerous lasers for the treatment of unwanted hair. Laser wavelength is a key factor influencing treatment efficacy and complication rates.
Objective. To compare the efficacy and safety of laser hair removal using three different laser systems.
Methods. A retrospective study of 805 consecutive laser-assisted hair removal treatments, conducted on 75 patients by means of either a long-pulsed Nd:YAG, a long-pulsed alexandrite, or a long-pulsed diode laser is reported. All patients were evaluated at least 3 months after the last treatment, and their present conditions were compared with the 1st-day photographs.
Results. The mean hair reduction was 42.4%, 65.6%, and 46.9% in Nd:YAG, alexandrite, and diode lasers, respectively. When the number of treatment sessions was taken into account, the efficacy of alexandrite and diode lasers was not significantly different, whereas both systems were more efficacious than Nd:YAG. Neither of the laser systems showed better results for a particular skin type. The occurrence of side effects was not significantly different between three laser systems.
Conclusion. Both long-pulsed alexandrite and long-pulsed diode laser systems are effective in the treatment of unwanted hair, and they are more efficacious than Nd:YAG laser.     

Laser tattoo removal

The availability of Q-switched ruby Nd:YAG and alexandrite lasers has revolutionized the treatment of tattoos. These modalities offer significant advantages over all previously available treatments and are currently the standard of care for the cosmetic removal of unwanted tattoos.     

A side-by-side comparative study of 1064 nm Nd:YAG, 810 nm diode and 755 nm alexandrite lasers for treatment of 0.3-3 mm leg veins.

BACKGROUND: Laser and intense pulsed light device treatments of leg veins have generally yielded disappointing results. Use of longer wavelengths, longer pulse widths, and better cooling devices have recently sparked renewed interests in these methods. OBJECTIVE: To prospectively compare, side by side, a 3-msec cryogen spray-equipped 755 nm alexandrite, a sapphire window cooled super-long-pulse 810 nm diode, and a variable pulse width, cryogen spray-equipped 1064 nm Nd:YAG laser for the treatment of 0.3-3mm leg veins. METHODS: Thirty female volunteers, skin types I-V, age 32-67 years with comparable sets of leg veins were treated with the Nd:YAG laser and either the diode laser, alexandrite laser, or both. In most patients two to three sets of comparable sites were treated. Treatment parameters varied with each laser and according to the size of veins being treated. Patients were examined 1 week after each treatment and at 1, 2, and 3 months after the last treatment. Pre- and posttreatment 35mm photographs were taken. Improvement was judged by two experienced physicians both visually on patients and by comparison of pre- and posttreatment photographs. Results were graded as percent resolution, in five groups, 0%, 0-25%, 25-50%, 50-75%, and 75-100%. RESULTS: In the 22 patients completing the study, 36 leg vein sites were treated with the Nd:YAG laser, 18 leg vein sites were treated with the diode laser, and 12 leg vein sites were treated with the alexandrite laser. Greater than 75% improvement was observed at 88% of the Nd:YAG laser-treated sites, 29% of the diode laser-treated sites, and 33% of the alexandrite laser-treated sites. Greater than 50% improvement was observed at 94% of the Nd:YAG laser-treated sites, 33% of the diode laser-treated sites, and 58% of the alexandrite laser-treated sites. Less than 25% improvement was observed at 6% of the Nd:YAG laser-treated sites, 39% of the diode laser-treated sites, and 33% of the alexandrite laser-treated sites. Pain during treatment was variably perceived by patients, but occasionally sufficient for patients to decline further treatment. Posttreatment purpura and telangiectatic matting were a significant drawback for the alexandrite laser. Transient hemosiderin pigmentation, as seen with sclerotherapy, was common with larger vessels. CONCLUSION: The cryogen spray-equipped 1064 nm Nd:YAG laser was remarkably effective and safe for the treatment of 0.3-3 mm leg veins. The use of topical anesthesia may be needed for some patients. The super-long-pulse 810 nm diode laser gave unpredictable results. Additional refinements of fluence and pulse width could improve its performance. The 3-msec, 755 nm alexandrite laser at fluences of 60-70 J/cm2 and an 8 mm spot can be effective, but inflammatory response, purpura, and matting limit its usefulness. Longer pulse widths might decrease these problems. For leg vein treatment, the 1064 nm wavelength is very safe for type V skin, the 810 nm wavelength at super-long pulse widths of 400-1000 msec is very safe for type IV and marginal for type V skin, and the 755 nm wavelength is limited to nontanned type I-III skin.     

In vivo photoacoustic imaging of blood vessels with a pulsed laser diode

Photoacoustic imaging is a hybrid imaging modality that is based on the detection of acoustic waves generated by absorption of pulsed light by tissue chromophores such as hemoglobin in blood. For this technique, usually large and costly Q-switched Nd:YAG lasers are used. These lasers provide a pulse energy of at least several milliJoules. In search of alternative light sources, we investigated the use of a small and compact pulsed laser diode to image blood vessels. We proved that a pulsed laser diode can be applied for imaging blood vessels in vivo.     

Treatment of Acquired Bilateral Nevus of Ota-Like Macules (Hori''s Nevus) with a Combination of the 532 nm Q-Switched Nd:YAG Laser Followed by the 1,064 nm Q-Switched Nd:YAG Is More Effective: Prospective Study

BACKGROUND: Acquired bilateral nevus of Ota-like macules (Hori's nevus) is a common dyschromatosis among Asian women. Q-switched lasers have been used successfully as a treatment modality. OBJECTIVE: The purpose of this study was to compare the efficacy of using the Q-switched 532 nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser followed by the 1,064 nm laser versus the Q-switched 1,064 nm Nd:YAG laser alone in the treatment of Hori's nevus. METHODS: This is a prospective left-right comparative study. Ten women with bilateral Hori's nevus were recruited and treated with a combination of the Q-switched 532 and 1,064 nm Nd:YAG lasers on the right cheek and the Q-switched 1,064 nm Nd:YAG laser alone on the left cheek. Only one laser treatment session was performed. The degree of pigmentation was objectively recorded with a mexameter. Subjective assessment was made by both patients and two blinded, nontreating dermatologists. RESULTS: At 6 months, there was a statistically significant difference (p = .009) of 35.10 points using objective mexameter measurements between the two sides, favoring the side treated with a combination of 532 and 1,064 nm laser treatment. Subjective grading by the patients and blinded dermatologists also confirmed that combination therapy was more successful after one treatment. Although combination treatment had a higher incidence of mild postinflammatory changes, this disappeared within 2 months. CONCLUSIONS: Concurrent use of the Q-switched 532 nm Nd:YAG laser in combination with the 1,064 nm laser is more effective in pigment clearance than the Q-switched 1,064 nm Nd:YAG laser alone for Hori's nevi.     

The effect of frequency doubled double pulse Nd:YAG laser fiber proximity to the target stone on transient cavitation and acoustic emission

PURPOSE: Scant information has been published describing the effect of laser fiber distance from the stone target on the mechanism of calculus fragmentation. Using high speed photography and acoustic emission measurements we characterized the impact of laser fiber proximity on stone comminution. We evaluated the effect of laser fiber distance from the stone target on resultant cavitation bubble formation and shock wave generation. MATERIALS AND METHODS: Stone fragmentation was assessed using a FREDDY (frequency doubled double pulse Nd:YAG) (World of Medicine, Orlando, Florida) laser and a holmium laser. The FREDDY laser was operated using a 420 microm fiber at an output energy of 120 and 160 mJ in single and double pulse settings, and a pulse repetition rate of 1 Hz. The holmium laser was operated using a 200 microm fiber at an output energy of 1 to 3 J and a pulse repetition rate of 1 Hz. The surface of a 1 cm square BegoStone (Bego, Bremen, Germany) attached to an X-Y-Z translational stage was aligned perpendicular to the laser fiber, which was immersed in a Lucite tank filled with water at room temperature. An Imacon 200 high speed camera was used to capture transient cavitation bubbles at a framing rate of up to 1,000,000 frames per second. Acoustic emission signals associated with shock waves generated during the rapid expansion and collapse of the cavitation bubble were measured using a 1 MHz focused ultrasound transducer. RESULTS: At laser fiber distances of 3.0 mm or less cavitation bubbles and shock waves were observed with the FREDDY laser. In contrast to the holmium laser, the bubble size and shock wave intensity of the FREDDY laser was inversely related to the fiber-to-stone distance over the range tested (0.5 to 3.0 mm). CONCLUSIONS: While bubble size was noted to increase with a larger stone-to-fiber distance using the holmium laser, to consistently generate cavitation bubbles and shock waves using the FREDDY laser the laser fiber should be operated within 3.0 mm of the target stone. These findings have significant implications during clinical laser stone fragmentation.     

Treatment of Facial Skin Using Combinations of CO2, Q-Switched Alexandrite, Flashlamp-Pumped Pulsed Dye, and Er:YAG Lasers in the Same Treatment Session

BACKGROUND: Many patients who seek facial CO2 laser resurfacing for improvement of photodamage are also concerned with "dark circles" under their eyes (periorbital hyperpigmentation) and/or telangiectasia as well as various types of deep scars on their faces. CO2 laser resurfacing alone provides limited improvement for these problems. OBJECTIVE: The purpose of this study was to demonstrate the conjunctive therapeutic effects of the CO2, Q-switched alexandrite, Er:YAG, and/or flashlamp-pumped pulsed dye lasers on facial skin treatments. METHOD: Thirty patients who underwent CO2 laser resurfacing were treated with additional lasers specific for their cosmetic concerns. Twenty patients with facial telangiectasias were treated with the pulsed dye laser immediately prior to CO2 laser resurfacing. Eleven patients with periorbital hyperpigmentation were treated with the Q-switched alexandrite laser immediately following use of the pulsed CO2 laser. Eight patients having sharply defined acne scars were treated with the Er:YAG laser following use of the CO2 laser. All patients had peripheral feathering performed with the Er:YAG laser. Nine patients were treated with all four lasers. RESULTS: In addition to significant improvement of the wrinkle scores from the CO2 laser resurfacing, patients had 75-100% clearing of the periorbital hyperpigmentation. All patients with facial telangiectasia showed virtually 100% improvement. All deep wrinkles and sharply defined scars responded with combined CO2/Er:YAG laser better than with CO2 laser resurfacing alone. All feathering was more uniform, with a more subtle transition to nontreated skin. There were no complications that could be attributed to the simultaneous use of multiple lasers. CONCLUSIONS: For patients who present with multiple cosmetic complaints, combined treatment using appropriate lasers offers excellent therapeutic outcome.