Comparative histological studies of the tunable dye (at 577 nm) laser and argon laser: the specific vascular effects of the dye laser

Indocyanine green conjugated phototheranostic nanoparticle for photodiagnosis and photodynamic reaciton

BACKGROUND

Phototheranostics represents a highly promising paradigm for cancer therapy, although selecting an appropriate optical imager and sensitizer for clinical use remains challenging.

METHODS

Liposomally formulated phospholipid-conjugated indocyanine green, denoted as LP-iDOPE, was developed as phototheranostic nanoparticle and its cancer imaging-mediated photodynamic reaction, defined as the immune response induced by photodynamic and photothermal effects, was evaluated with a near-infrared (NIR)-light emitting diode (LED) light irradiator.

RESULTS

Using in vivo NIR fluorescence imaging, we demonstrated that LP-iDOPE was selectively delivered to tumor sites with high accumulation and a long half-life. Following low-intensity NIR-LED light irradiation on the tumor region of LP-iDOPE accumulated, effector CD8⁺ T cells were activated at the secondary lymphoid organs, migrated, and subsequently released cytokines including interferon-γ and tumor necrosis factor-α, resulting in effective tumor regression.

CONCLUSIONS

Our anti-cancer strategy based on tumor-specific LP-iDOPE accumulation and low-intensity NIR-LED light irradiation to the tumor regions, i.e., photodynamic reaction, represents a promising approach to noninvasive cancer therapy.

Dose-dependent study of effects of 532-nm continuous wave laser on rat skin: A mechanistic insight

Visible lasers emitting in the green spectral region are being routinely employed in various medical and defense fields namely treatment of pigmented lesions, tattoo inks, port wine stains, dazzling the target or mob dispersal. Despite their increasing applications, lasers also tend to pose occupational hazards to operators, ancillary personnel, individuals undergoing laser therapies. This study was aimed at investigating the effects of different doses of 532-nm continuous wave laser on rat skin. The present study demonstrated that higher fluences of 532-nm continuous wave (CW) laser induces significant tissue damage through induction of tumor necrosis factor-α, cyclooxygenase-2, tumor protein (p53), PARP 1, caspase3 which in turn leads to tissue damage and cell death. Furthermore, level of heat shock proteins, pAkt were found up-regulated as a cope up response to laser-induced stress. On the basis of the findings, irradiation with 532-nm CW laser up to 2.5 J/cm² was found within the safe exposure limits. Thus, it is probably the first attempt to demonstrate the tissue damage induced by 532-nm CW laser on skin, which may help in choosing safe laser dose for certain skin-based applications and evolving methods to ameliorate laser-inflicted injuries.

Current treatment and management of infantile hemangiomas

Infantile hemangiomas, otherwise known as infantile capillary hemangiomas, strawberry hemangiomas, or strawberry nevi, are nonmalignant vascular tumors that commonly affect children. The natural disease course typically involves growth for up to a year, followed by regression without treatment over a period of years with no cosmetic or functional sequelae. Less commonly, however, infantile hemangiomas can become a threat to vision or even life depending on location and size of the lesion. In addition, infantile hemangiomas, particularly those involving the face, may be disfiguring and result in lifelong sequelae. β-blockers have become a mainstay of therapy given their relatively low-risk profile and efficacy. Other treatment modalities previously described in the literature include corticosteroids (both intralesional and systemic), imiquimod, vincristine, bleomycin A5, and interferon α. More recently, angiotensin-converting enzyme inhibitors such as captopril have been used. Laser therapy and, less commonly, surgical excision are also available treatment options. We review current recommended management and treatment of capillary hemangiomas and discuss the benefits and risks of all previously reported treatment modalities.

Pulsed Dye Laser Treatment of Laryngeal Granulomas

Laryngeal granulomas are effectively treated with antireflux therapy and speech therapy. Failure to respond leads to treatment with Botox or surgical excision. We report on the use of the pulsed dye laser for treating chronic granulomas that do not respond to standard therapy. We performed a retrospective review from September 2002 to September 2003. Patients identified with chronic granulomas that were not responding to standard therapy were treated in our office with the pulsed dye laser. Ten patients were identified; the mean age was 58 years. Two patients underwent more than one pulsed dye laser treatment. Five of the 10 had resolution of their lesions, and 3 had a partial response. Two were unchanged. The average follow-up was 6 months, and there were no complications. We conclude that in-office use of the pulsed dye laser is a relatively safe and effective method for treating laryngeal granulomas that do not respond to antireflux therapy and speech therapy.

Patient Tolerance of In-Office Pulsed Dye Laser Treatments to the Upper Aerodigestive Tract

INTRODUCTION: Recent advances in technology have facilitated a movement toward unsedated in-office treatment of laryngeal, tracheal, and esophageal lesions. The objective of this study was to determine patient tolerance of inoffice pulsed-dye laser (PDL) treatment of upper aerodigestive tract pathoses via the transnasal esophagoscope.

METHODS: Three hundred twenty-eight unsedated in-office PDL cases were performed at a university-based tertiary referral center in 131 patients. These procedures were performed for various upper aerodigestive pathoses, including recurrent respiratory papillomatosis, chronic granulomas, and recurrent leukoplakia. Eighty-nine subjects completed a phone survey concerning their discomfort level after the PDL procedure. They were also asked specific questions about recovery time, pain medication, and preference of operating room versus inoffice procedures.

RESULTS: The average comfort score was 7.4 (10 being minimal discomfort). Eighty-four percent did not use any pain medication; 87% stated that, if possible, they would prefer to undergo unsedated inoffice procedures rather than surgeries under general anesthesia for further treatment of their upper aerodigestive tract pathosis.

CONCLUSIONS: Unsedated transnasal treatment of upper aerodigestive tract pathoses is readily accepted and well-tolerated by otolaryngology patients. Patients overwhelmingly prefer the inoffice PDL over surgeries under general anesthesia.

Five parameters you must understand to master control of your laser/light-based devices

In this article, the authors review basic fundamental principles of light characteristics and their interaction with the target tissue. It is imperative for the practitioner to understand these concepts to deliver appropriate, efficacious, and safe phototherapeutic treatment for their patients. Once a diagnosis is made and a laser is chosen as a treatment tool, a basic knowledge and understanding of the physics and properties of light/tissue interaction is essential to allow practitioners to provide their patients with optimal results.

Introduction to fiber optics: Sensors for biomedical applications

The paper focuses on the introduction of fiber optics, a fusion of science and engineering and describes the materials generally used for its construction along with the procedure used to design the fibers. It gives an idea of the materials used for the construction along with the pros and cons associated with them and various factors governing the emission of ultraviolet, infrared or visible radiations. The central core revolves around the applications of optical fibers in the medical and biomedical field and extending the use of the same in pharmaceutical industry as probes in quality control and dosage form analysis.

Laser treatment of pediatric vascular lesions: Port wine stains and hemangiomas

Pediatric vascular lesions can be medically threatening and psychologically distressing to patients. This article reviews literature on the laser treatment of two common pediatric vascular lesions, port wine stains and hemangiomas. The purpose of this report was to distinguish the lesions from one another and to present the advantages, disadvantages, complications, and limitations of laser treatment for each lesion type. This review is not a comprehensive inventory but instead highlights the studies that best show promising results or the limitations of laser treatment for the lesions. Overall, port wine stain laser treatment promoted notable clearing with low side effects, whereas hemangioma laser treatment provided inconsistent benefits and severe side effects occasionally. Laser treatment of port wine stains is safe and effective, but laser treatment of hemangiomas remains controversial and is best for lesions without deeper components.

Masers to magic bullets: an updated history of lasers in dermatology

Laser therapy is one of the fastest expanding and most exciting fields in dermatology. From its theoretical beginnings in Einstein's imagination, lasers have come to be used in treatments for conditions ranging from skin malignancy and acne to hirsutism and photoaging. We will briefly review the evolution of laser treatment, with a focus on the recent developments surrounding the new millennium.

Plasmonic photothermal therapy (PPTT) using gold nanoparticles

The use of lasers, over the past few decades, has emerged to be highly promising for cancer therapy modalities, most commonly the photothermal therapy method, which employs light absorbing dyes for achieving the photothermal damage of tumors, and the photodynamic therapy, which employs chemical photosensitizers that generate singlet oxygen that is capable of tumor destruction. However, recent advances in the field of nanoscience have seen the emergence of noble metal nanostructures with unique photophysical properties, well suited for applications in cancer phototherapy. Noble metal nanoparticles, on account of the phenomenon of surface plasmon resonance, possess strongly enhanced visible and near-infrared light absorption, several orders of magnitude more intense compared to conventional laser phototherapy agents. The use of plasmonic nanoparticles as highly enhanced photoabsorbing agents has thus introduced a much more selective and efficient cancer therapy strategy, viz. plasmonic photothermal therapy (PPTT). The synthetic tunability of the optothermal properties and the bio-targeting abilities of the plasmonic gold nanostructures make the PPTT method furthermore promising. In this review, we discuss the development of the PPTT method with special emphasis on the recent in vitro and in vivo success using gold nanospheres coupled with visible lasers and gold nanorods and silica-gold nanoshells coupled with near-infrared lasers.

Intense pulsed light treatment of 1,000 consecutive patients with facial vascular marks

BACKGROUND

Facial teleangectasias or vascular marks often represent a very cosmetically detracting problem for the affected patient, who tries to cover the lesions by camouflage strategies. This study describes the response of these vascular lesions after an intense pulsed light source was used on 1,000 consecutive patients.

METHODS

Between October 1998 and April 2005, 1,000 consecutive patients with various skin types (Fitzpatrick I to IV) were treated with Photoderm VL. The average age of the patients was 47.1 years. These patients were subjected to a mean of 2.16 treatments (range, 1-9), then followed up 48 h, 72 h, 1 week, 3 weeks, and 1 month after each treatment. All the patients were followed up 2 months after the last treatment, and the percentage of clearance was assessed by comparison of pre- and posttreatment photographs. The patients also answered a questionnaire in which they expressed personal satisfaction. The final physicians-nurse evaluation also was recorded on the same form.

RESULTS

Most of the patients (89.70%) experienced a clearance of 75% to 100%. The results appear to be correlated with operator experience, but not with lesion size, age, or skin type. Minimal adverse side effects occurred for 14.6% of the patients, but only for 6.76% of the treatments.

CONCLUSION

The intense pulsed light source Photoderm VL can be considered a fast, safe, and effective treatment for facial teleangectasias or vascular marks.

Selective photothermolysis of blood vessels following flashlamp-pumped pulsed dye laser irradiation: in vivo results and mathematical modelling are in agreement

Laser therapy using the pulsed dye laser is the standard treatment for port-wine stains (PWS). But the mechanism of action has not been elucidated completely, yet. The dorsal skin-fold chamber model in hamsters was used to investigate the effects of laser treatment (lambda(em)=585 nm; pulse duration: 0.45 ms; fluence: 6 J per cm2) on blood vessels. Vessels (n=3394) were marked with FITC dextran (MW 150 kDa) and diameters (2-186 microm) were measured using intravital fluorescence microscopy up to 24 h following irradiation. Histology (H&E, TUNEL, CD31) was taken 1 or 24 h after irradiation. The experimental results were compared with the predictions of a mathematical model based on the finite-element method. Following irradiation treatment the number of unperfused vessels decreases with decreasing vessel diameter in vivo. Histology indicated a restriction of tissue injury to the irradiated area after 1 h. Blood vessels contained aggregated red blood cells. After 24 h tissue damage occurred also outside the irradiated area and thrombus formation was visible. These results were in agreement with the mathematical calculations. In addition to initial physical effects after pulsed dye laser treatment delayed biological processes contribute significantly to the reduction of perfused blood vessels. Because of incomplete photocoagulation of smaller blood vessels (diameter 2-16 microm) a complete bleaching of PWS seems to be unlikely.

Facial teleangectasias: Our experience in treatment with IPL

BACKGROUND AND OBJECTIVES

Facial teleangectasias can be a relevant cosmetic problem, which the patient usually hides with a thick layer of makeup. This study will describe the response on these vascular lesions using the intense pulsed light (IPL) source.

METHODS

Five hundred eighteen consecutive patients were treated with Photoderm VL (Lumenis Ltd.). The average age of patients of various skin types (Fitzpatrick I to IV) was 48.5 years. They were subjected to a mean of 1.69 treatments (range 1-9) followed up 48 hours, 72 hours, 1 week, 3 weeks, and 1 month after each treatment. All patients were followed up after 2 months from the last treatment and the percentage of clearance was assessed by comparing pre- and post-treatment photographs. The patients also answered a questionnaire in which they expressed personal satisfaction. The physicians evaluation was also recorded on the same form.

RESULTS

Patients (87.64%) presented a clearance of 75%-100%. The results appear not correlated with lesions size, age, skin type but with operator experience. Minimal side adverse effects occurred in 20% of the patients.

CONCLUSION

The IPL source, Photoderm VL, can be considered an alternative or a supplement to the existing laser devices for facial teleangectasias treatment.

Laser surgery: an approach to the pediatric patient

Revolutionary advances in laser research and technology have led to expanded dermatologic laser applications. With the wide range of lasers now available, a large spectrum of skin conditions in the pediatric population can be successfully treated or, in some cases, completely eradicated. Laser treatment of the pediatric population poses a unique challenge for the clinician on a variety of levels. Physically, the composition of many vascular and pigmented lesions changes as children age making them more resistant to laser therapy. Thus, in many cases, treating lesions at an early age has resulted in clearing in fewer sessions and with decreased complications. Mechanically, lasers and laser settings used for the treatment of adult lesions may have to be adjusted for the smaller vessels and the unpredictable nature of scarring with children's skin. For vascular lesions, the pulsed dye laser is considered the laser of choice for its efficacy and low-risk profile, whereas the Q-switched, pigment-specific lasers are ideal for most childhood pigmented lesions, allowing for single pigment cell destruction. Other conditions such as acne and acne scars, psoriasis, keloids, warts and hypertrichosis that traditionally have been treated with a variety of modalities are now being managed safely with laser surgery. Other issues specific to the pediatric population include the determination of suitable anesthesia, the provision of size-appropriate safety equipment, and the assessment and management of patient and parent anxiety. The use of lasers specifically designed for structural differences in pediatric lesions and the recognition of emotional issues surrounding a young patient during laser surgery are critical components of successful treatment.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be familiar with the mechanism of laser technology, current trends in the use of lasers for skin lesions in the pediatric population, and the issues specific to treating a patient with laser surgery.

Mechanisms of Microvascular Response to Laser Pulses

"Selective photothermolysis" is widely used for treating vascular lesions. In order to understand mechanisms of response, we investigated fast events during pulsed laser treatment of microvessels. A high-speed (2000 fps) CCD camera and microscope were used to image hamster cheek pouch microvessels during and after 532 nm and 1064 nm laser pulse exposures. Pulse duration and fluence were varied systematically (1-50 ms, 0-600 J per cm2). Threshold fluences for fast events were determined. On a millisecond time-scale, a specific series of fast events occur, which are wavelength, fluence, irradiance, and pulse duration dependent. In order of increasing fluence we observed: blood coagulation, vasoconstriction, thread-like appearance of the treated vascular segment, vessel disappearance, intravascular cavitation, bubble formation, vessel wall rupture and hemorrhage, and shrinkage of perivascular tissue. With increasing pulse duration, the threshold fluences for coagulation, vessel disappearance, and cavitation increase, and cavitation becomes less violent, conforming to the vessel lumen. Intravascular cavitation did not always rupture the vessel wall, and is not the mechanism for immediate vessel disappearance, a desired endpoint for treating vascular lesions. The apparent mechanism for immediate vessel disappearance is contraction of intravascular blood and perivascular collagen after thermal denaturation. This study suggests that detecting fast events in humans, in real time, may provide useful feedback signals for "smarter" laser devices.

Optimal management of facial telangiectasia

Telangiectasia can be treated with many different modalities. Electrosurgery is effective but dependent on technique. Sclerotherapy can be used on larger blue telangiectasia but may be complicated from inadvertent injection into arterioles. Surgical phlebectomy can be used on reticular veins but is technically difficult. Many different laser wavelengths can be successfully used to minimize and/or eliminate vascular lesions on the face. Each type of laser has advantages unique to its profile of wavelength, pulse duration, spot size and cutaneous cooling. The benefits of using 532-595 nm lasers are the multiple applications of these lasers on treating not only telangiectasia, but also pigmentation and even fine wrinkles. Newer methods of cutaneous cooling and lengthening of pulse duration make these lasers less painful with fewer adverse effects (purpura) than previous lasers. The benefit in using a 1064 nm laser is that its longer wavelength can penetrate more deeply, allowing effective thermosclerosis of vessels up to 3-4 mm in diameter. In addition, the 1064 nm wavelength permits treatment of patients of skin types I-VI with or without a tan, since melanin absorption is minimal.

585-nm pulsed dye laser treatment of glottal papillomatosis

Treatment of recurrent respiratory papillomatosis of the glottis is often challenging. The surgeon and patient must cooperatively balance decisions regarding airway safety, effects of multiple general anesthesias, employment disturbance, and vocal dysfunction. A pilot study was done in 41 adult cases (23 patients; 78 vocal folds) without complication to evaluate the effectiveness of a 585-nm pulsed dye laser (PDL; 450-micros pulse width; fluence of 38 to 255 J/cm2; 1- to 2-mm spot size) in the treatment of this disorder. Thirty-seven of the 41 cases (90%) were bilateral disease. Twenty-six of the 41 cases (63%; including 20 cases with involvement of the anterior commissure) were treated by bilateral photocoagulation of the lesions' microcirculation without microflap resection of tissue. Clinical observation revealed that irradiated but unresected disease involuted without development of an anterior commissure web. In the initial 13 of the 41 cases (32%), PDL treatment was followed by cold instrument microflap resection. The PDL enhanced the epithelial excision by improving hemostasis and by creating an optimal dissection plane between the basement membrane and the underlying superficial lamina propria. The PDL at 585 nm was less effective in the management of exophytic lesions because of its limited depth of penetration (approximately 2 mm). In this initial trial, the PDL was a relatively safe and efficacious treatment for glottal recurrent respiratory papillomatosis. Since the lesions involute without complete resection of the diseased epithelium, the anterior commissure can be treated to minimize the number of procedures. To study patterns of recurrence will require longer follow-up.

Treatment of a resistant port-wine stain with the 1.5-msec pulse duration, tunable, pulsed dye laser

BACKGROUND

Pulsed dye lasers (PDLs) have been developed with relatively long pulse durations in comparison to their predecessors.

OBJECTIVE

To demonstrate the efficacy of the 1.5-msec PDL for treating a port-wine stain that was resistant to the 0.5-msec PDL.

METHODS

A 31-year-old man with a congenital port-wine stain underwent treatment with the PDL seven times over approximately 2 years. Although it lightened, no areas demonstrated complete clearing. He recently presented for treatment with the 1.5-msec PDL.

RESULTS

Initial results of treatment with a 1.5-msec PDL on this patient's port-wine stain demonstrate dramatic clearance of areas previously treated with an identical fluence using a 0.5-msec PDL.

CONCLUSION

Longer pulse duration PDLs should be further investigated for the treatment of port-wine stains and may offer improved efficacy over shorter pulse durations.

The role of dermatologists in the evolution of laser surgery

The role dermatologists have played throughout the history of laser development is an extremely vital one. The initial interests of Dr. Leon Goldman stimulated many other individual dermatologists to further his work and develop surgical techniques using newer laser systems to provide more effective treatment for patients with a variety of skin diseases. The long list of current cutaneous laser applications developed by dermatologists makes it virtually certain that members of our specialty will continue to play a significant future role in the refinement of laser instrumentation and operative techniques that are inevitable to occur.

Response of associated oral soft tissues when exposed to Argon laser during polymerization of dental resins

BACKGROUND AND OBJECTIVE

Polymerization of dental resins with Argon laser produces restorations with improved physical properties when compared to conventional visible-light polymerization techniques. However, the possibility of damaging adjacent soft tissues has not been addressed.

STUDY DESIGN/MATERIALS AND METHODS

In this study, Argon laser (488/514 nm) was used for the polymerization of composite resins to determine effects on the parakeratinized gingiva adjacent to both restored and unrestored teeth in six dogs, using 10-, 20-, and 30-second polymerization exposures.

RESULTS

Gingival tissues removed at 24 hours, 72 hours, or 5 days revealed desiccated, disrupted, hyalinized connective tissue. Tissues exposed for 10 seconds showed minimal change. This minimal degree of change was most evident at 72 hours and returned to normal limits at 5 days. The 20-second exposure produced alterations evident through all time periods. Tissues exposed for 30 seconds exhibited necrosis, severe disruption, and vessiculation, which was still unresolved at 5 days.

CONCLUSION

This study demonstrates that clinically relevant Argon laser exposure (10 seconds) of parakeratinized gingiva adjacent to teeth undergoing restoration does not cause lasting damage.

Comparison of flash lamp pulsed-dye laser (585 nm) and conventional surgery in the delay of random dorsal rat flaps

BACKGROUND AND OBJECTIVE

Delay is a basic surgical technique used by flap surgeons to improve the blood supply to the distal parts of a random skin flap. The aim of this study was to determine whether a scarless delay can be done by the use of the flash lamp pulsed-dye laser operating at a wavelength of 585 nm.

STUDY DESIGN/MATERIALS AND METHODS

The pilot study showed that 6 J/cm(2) had a selective photothermolysis effect and therefore was chosen for testing the delay procedure on 15 rats. The percentage of flap necrosis of this group was compared to the results of 15 rats that underwent delay by surgery and 15 rats that were not treated prior to flap surgery (control group).

RESULTS

Laser delay of McFarlane flaps resulted in an average of 15.5% smaller necrotic area compared to the control group (52.7% +/- 14.4% and 68.2% +/- 9.6%, respectively, P < 0.01) and was as effective as surgical delay (53.3% +/- 13.6%).

CONCLUSIONS

The results indicate that the flash lamp pulsed-dye laser operating at 585 nm is effective for delaying cutaneous flaps in the rat model.

Clinical effects of dynamic cooling during pulsed laser treatment of port-wine stains

Pulsed dye lasers permit effective treatment of port-wine stains without a significant risk of complications. However, epidermal damage manifested by weeping or crusting of the treated area have been reported in 48-83% of patients, and transient hyperpigmentation after treatment is observed in 10-57%. Theoretically, the epidermis can be protected from thermal damage with the use of the concept of selective epidermal cooling.This study examined the clinical effects of rapid cooling of the epidermis with a liquid refrigerant R-134a (boiling point - 26.5 double daggerC) during pulsed dye laser therapy. In 23 patients with port-wine stains, a 50-ms-long cooling pulse delivered immediately prior to laser irradiation with a fluence of 6.0 J cm(-2) significantly reduced the pain, and shortened the period with purpura without compromising the clinical blanching. Cooling periods longer than 60 ms, as well as additional cooling pulses immediately after laser exposure, reduced the blanching in areas irradiated with 6.0 J cm(-2).Post-treatment hyperpigmentation was not prevented with dynamic cooling.

Copper vapour laser treatment of port-wine stains in brown skin

Forty-seven Korean patients with port-wine stains were treated with a copper vapour laser and clinical responses were assessed at three months after the last treatment by comparing photographs taken before each treatment. The immediate histologic changes within 15 min after laser treatment were also observed by routine H&E and nitroblue tetrazolium chloride staining. When we treated port-wine stains with minimal whitening doses of 6-8 J/cm2, no or slight colour changes were obtained. Thus, all port-wine stain lesions in this study were treated with non-specific energy densities ranging from 10-20 J/cm2. Good to excellent results were obtained in 18 (38.2%) of 47 Korean patients with port-wine stains. Repeated treatment can continue to reduce colour. Darker lesions (purple or red) are more likely to result in a marked colour change. At above threshold dose, there was wedge-shaped diffuse coagulation necrosis and loss of viability of the epidermis and underlying dermis. Even though copper vapour laser treatment of port-wine stains in brown skin is not as selective as in white skin because of epidermal melanin, our clinical data demonstrate the usefulness of the copper vapour laser for the treatment of port-wine stains in brown skin.

Histological responses of port wine stains in brown skin after 578 nm copper vapor laser treatment

BACKGROUND AND OBJECTIVES

The object of this study is to characterize the effects of epidermal melanin in brown skin on selective vessel damage by copper vapor laser radiation in port wine stain (PWS). STUDY DESIGN/MATERIALS, AND METHODS: We observed the histological changes of PWS in Korean patients who received copper vapor laser (578 nm) treatment over a range of energy densities (6-14 J/cm2) and exposure durations (30-200 ms). The nitroblue tetrazolium chloride (NBTC) staining method was used to differentiate between the blue-stained viable cells and the unstained thermally damaged cells.

RESULTS

With Fontana-Masson stain, we found that Korean skin has more epidermal melanin than Caucasian skin. For energy densities greater than 6 J/cm2, epidermal damage was observed. At 6 and 8 J/cm2, the damage to the dermis was localized to the blood vessels and the perivascular tissue. The connective tissue between damaged vessels and epidermis was still viable. Energy densities above 10 J/cm2 produced a diffuse thermal necrosis. We conclude that vascular selectivity without epidermal damages cannot be achieved with a 50 ms exposure at 578 nm in the brown skin of Koreans. The energy density for clinical minimal whitening was 6-8 J/cm2, and the maximum penetration depth of these energy densities was 0.4 mm. We also found that the epidermal damage increased with increasing pulse widths at a fixed energy density (10 or 8 J/cm2) while the severity and depth of vascular damage decreased. These findings suggest that it is best to treat PWS with a copper vapor laser at the minimal pulse width and maximal power output possible at given energy density.

CONCLUSION

We have demonstrated that the copper vapor laser treatment of PWS in the brown skin is not as selective as in white skin because of epidermal melanin.

Thermal relaxation of port-wine stain vessels probed in vivo: the need for 1-10-millisecond laser pulse treatment

Although thermal relaxation times of cutaneous port-wine stain microvessels have been calculated and used to formulate laser selective photothermolysis, they have never been measured. A scheme to do so was devised by measuring the skin response to pairs of 585-nm dye laser pulses (250-360 microseconds each) as a function of the time interval between the two pulses, in five volunteers with port-wine stains. After a pump pulse delivering 80% of the fluence necessary for causing purpura, the fluence of a second probe pulse necessary to cause purpura was determined and was found to increase with the interval between the two pulses, in a manner consistent with thermal diffusion theory. Biopsy specimens were obtained from four of the five subjects to examine the nature and extent of vessel damage and to measure the port-wine stain vessel diameters. Using diffusion theory, the thermal relaxation time was calculated based on the measured vessel diameters. These calculated values are consistent with the increase in radiant exposure (fluence) of the probe pulse necessary to induce purpura for longer time delays. Two simple models for thermal relaxation of port-wine stain vessels are presented and compared with the data. The data and histologic assessment of the vessel injury strongly suggest that pulse durations for ideal laser treatment are in the 1-10-millisecond region and depend on vessel diameter. No dermatologic lasers presently used for port-wine stain treatment operate in this pulse width domain.

Dye laser treatment of port-wine stains: comparison of the continuous-wave dye laser with a robotized scanning device and the pulsed dye laser

BACKGROUND

Despite good results in the treatment of most port-wine stains (PWS) with continuous-wave visible-light lasers, light PWS and those in certain locations respond less favorably and have a higher risk of scarring. Robotized scanning devices such as the Hexascan device have been developed for continuous-wave laser sources to produce greater target specificity, to increase reproducibility of results, and to decrease the incidence of adverse effects.

OBJECTIVE

The purpose of this study was to compare the effects of the same wavelength of light (585 nm) on test sites within PWS with the flashlamp-pumped pulsed dye laser and a continuous-wave tunable dye laser scanned through a Hexascan robotized scanning device.

METHODS

Two adjacent, noncontiguous sites within PWS were treated in 29 patients, one site with the flashlamp-pumped pulsed dye laser and the other with an argon-pumped continuous-wave tunable dye laser affixed to a Hexascan device.

RESULTS

Twenty-eight patients completed the study. The pulsed dye laser was found to be superior to the continuous-wave dye laser with the Hexascan device in 45% of patients, whereas the continuous-wave tunable dye laser with the Hexascan device was considered superior in 15%. There was no difference in the remaining 40%. Undesirable side effects were infrequent with both treatments. There was no significant difference in hypopigmentation or atrophic and hypertrophic scarring, but hyperpigmentation was more frequent with the continuous-wave dye laser with the Hexascan device.

CONCLUSION

Both the pulsed dye laser and continuous tunable-wave dye laser with the Hexascan device produce slight lightening after one treatment. The pulsed dye laser produces slightly greater lightening than the continuous-wave tunable dye laser with the Hexascan device 6 weeks after treatment of test areas within PWS in 40% of those treated. It also produced slightly less hypopigmentation and hyperpigmentation.

Reflectance spectrophotometry in the objective assessment of dye laser-treated port-wine stains

At present, the treatment of choice for congenital capillary malformations of the port-wine stain type (PWS) is the flashlamp pulsed dye laser. Good results can be obtained in the majority of patients with this technique, but there is a group of poor responders. In the search for predictive tools to determine the therapeutic outcome, we have used a new photoelectric reflectance instrument. Sixty-six patients with PWS, mainly on the face, were treated with a pulsed dye laser during a 21-month period. Using a hand-held reflectance photometer, erythema indices were obtained for the PWS and normal skin. Based on these indices, a relative blanching effect could be calculated. The therapeutic result was judged to be excellent in 19, good in 20, fair in 14 and poor in 13 patients. There was a good correlation (r = 0.844) between the degree of blanching and the therapeutic result. In the 'excellent' category, an average blanching effect of 47% was present after the first treatment, and this increased to between 75 and 100% after successive treatments. In the 'poor' category, the blanching effect after one treatment averaged 14%, increasing to only 40% after up to six treatments. It thus seems to be possible to predict the outcome of therapy, which is of considerable help in treatment planning. Reflectance measurements, an objective estimate of blanching, correlate well with the clinical results, and are helpful in monitoring and predicting the therapeutic outcome in dye laser-treated PWS.

Pigmentation-dependent side effects to copper vapor laser and argon laser treatment

BACKGROUND AND OBJECTIVE

Melanin is a limiting factor for obtaining beneficial results in dermatological treatment of vascular malformations. The aim of our study was to establish a relation between pretreatment skin pigmentation and the occurrence of side effects.

STUDY DESIGN/MATERIALS AND METHODS

Thirteen human volunteers selected to have a varying degree of skin pigmentation were laser-treated on the inside of the brachium with an argon laser (AL, 488 nm and 514.5 nm) and a copper vapor laser (CVL, 578 nm), both connected to a Hexascan. Total exposure areas were 1.26 cm2 and beam diameters were 1 mm. Three intensities were used, 0.7, 1.0, and 1.3 W. Pulse duration was 200 ms, resulting in fluences of 17.8, 25.5, and 33.1 J/cm2. Pretreatment skin pigmentation was objectified by skin reflectance measurements.

RESULTS

At 1, 2, and 6 months after laser treatment, significant correlations were demonstrated between pretreatment skin pigmentation and laser-induced pigmentary changes and scar formation. At the 6-month assessment, the AL induced significantly higher scores of clinically evaluated scar formation as compared with the CVL (1.0 and 1.3 W/spot) and tended to induce higher clinical scores of pigmentary changes (not significant, ns).

CONCLUSIONS

We recommend skin pigmentation to be taken into consideration in dermatological laser treatment of vascular malformations.

Clinical uses of lasers in dermatology

The accessibility of the skin to examination and study has permitted dermatologists to play an extremely important role in defining the clinical usefulness and limitations of many laser systems as well as developing innovative concepts, techniques and devices that further improved the effectiveness of laser treatment. As new laser technology evolved over the years, dermatologists have also helped define the specificity of laser-tissue interaction and employed the newly developed laser technologies in innovative ways which further expanded the usefulness of these devices. One of the most important concepts to be developed by dermatologists--selective photothermolysis--has led to the creation of a series of laser systems which have provided numerous unique advantages in the management of many common vascular and pigmented conditions of the skin and mucous membranes, even in infants and children. The net result of these technologic advances has been the creation of new and effective treatment techniques which have been so profoundly superior to existing technology that they have been rapidly incorporated into the daily practice of most dermatologists.

Recent advances in the use of lasers In dermatology

A guide to laser treatment of port wine stains, tattoos and cutaneous pigmented disorders.

Comparison of the argon tunable dye laser with the flashlamp pulsed dye laser in treatment of facial telangiectasia

BACKGROUND

A prospective, side-by-side comparison study of the argon tunable dye laser (ATDL) and the flashlamp pulsed dye laser (FPDL) for the treatment of solar-induced telangiectasia was carried out in 14 patients with symmetrical bilateral cheek telangiectasias.

OBJECTIVE

The objective was to compare the efficacy of treatment by the two lasers.

METHODS

Patients were treated and examined at weeks 2, 4, and 6. Evaluation was done by direct observation and questionnaire, as well as by photographic slides projected to an impartial panel.

RESULTS

Final evaluation at week 6 showed 11 of 14 patients with excellent results at sites treated with the FPDL, compared with four of 14 with the ATDL. However, only six of 13 patients preferred the FPDL, due to the purpura and postinflammatory hyerpigmentation.

CONCLUSION

We conclude that the objective final results favor the FPDL over the ATDL for treatment of facial telangiectasia, but that the ATDL is still an important option for patient acceptance.

Pigmentation dependent, short time skin reactions to copper vapour laser and argon laser treatment

Thirteen human volunteers selected to have a varying degree of epidermal skin pigmentation were laser treated on the inside of the brachium in six hexagonal areas; three areas with an argon laser (AL, 488, 514.5 nm) and three corresponding areas with a copper vapour laser (CVL, 578 nm). The lasers were connected to a Hexascan device and the physical settings were identical for the two laser types, except for the wavelengths. Beam diameter was 1 mm, pulse duration 200 ms, intensities 0.7, 1.0 and 1.3 W/spot, corresponding to 14.1, 20.2 and 26.2J/cm2 per treated skin area. The skin pigmentation was objectified by skin reflectance. A correlation was demonstrated between skin pigmentation and wound healing time, maximum wound area, and the acute clinical response at days 0, 1, 4, 7, 11 and 17 after laser treatment. An increased skin pigmentation resulted in increased acute and subacute skin reactions. Comparison of the AL and the CVL demonstrated that the CVL on day 0 (0.7 and 1.0 W/spot) and on day 1 (0.7 W/spot) induced a significantly higher degree of skin reactions as compared with the AL. At 0.7 W/spot the CVL induced a significantly higher maximum wound area and a significantly prolonged wound healing time as compared with the AL. An inverse reaction existed between pigmentation and the threshold intensity required to induce wound formation.