585 nm for the treatment of port-wine stains

A feasible way to explore real blood vessels thermal responses to laser irradiation by combing optical clearing and the reflectance spectra measurements: animal experiment study

Laser therapy has been widely used to treat port-wine stains (PWS) and other cutaneous vascular lesions via selective photothermolysis. Animal models are a valuable tool for investigating thermal responses beneath the skin. However, in previous animal experiments, such as the dorsal skin chamber model, one side of the skin was removed, resulting in the loss of mechanical support for the target blood vessel. In this study, the optical clearing technique was applied to the dorsal skin, allowing direct observation of real thermal responses within the tissue without removing the covering skin. The target blood vessels were irradiated with a pulsed 1064 nm Nd: YAG laser. The corresponding thermal responses were recorded using a CCD camera. Additionally, variations in skin reflectance spectra were measured before and after laser irradiation. Due to the optical clearing and reflectance spectra measurement, vessel responses such as contraction, reperfusion, and full occlusion were correlated with specific variation patterns in reflectance spectral signals.

Vascular damage mechanism and parameter optimization under alexandrite laser irradiation: a theoretical study

The 755-nm Alexandrite Laser has a good clinical effect in treating resistant port wine stain, without causing thermal damage of normal tissue and side effects such as purpura. However, little is known about the mechanism of vascular damage induced by 755-nm laser irradiation, which restricts the optimization of laser parameters. In this work, the thermal damage model and the pressure damage model were used to study the damage mechanism of 755-nm laser irradiation on vessels, and the incident energy density and pulse width required for vascular damage were determined according to the damage mode. Under the irradiation of 755-nm laser, the vascular injury pattern was the co-occurrence of vessel rupture and vessel constriction, and the energy density required for the treatment of vessels with a diameter of 200 μm to reach the damage threshold was the lowest.

Contrasting the efficacy of pulsed dye laser and photodynamic methylene blue nanoemulgel therapy in treating acne vulgaris

The treatment of acne remains a challenge for dermatologists. A variety of conventional therapies are available for acne treatment such as topical and systemic medications. Although many of these traditional acne treatments are effective, the wide-spread nature of the disease and its sometimes resistant nature delineate the need for alternative therapies. Therefore, over the past decade, phototherapy has been introduced for the treatment of acne, such as pulsed dye lasers (PDLs) and photodynamic therapy (PDT). The aim of this study was to compare the safety and efficacy of PDL and methylene blue-mediated photodynamic therapy (MB-PDT) in the treatment of mild to moderate acne. Split-face clinical trial including fifteen patients presenting with mild to moderate acne were treated with 585 nm PDL on the right side of the face and MB-PDT with 665-nm diode laser on the left side. The photosensitizer MB was prepared in nanoemulgel formulation, and the treatment was carried out for three sessions maximum at 2-weeks intervals. Results revealed that both PDL and MB-PDT were effective therapies in the treatment of acne, as manifested by the reduction of inflammatory and non-inflammatory lesions throughout the treatment period. However, the latter therapy was proven more potent in the reduction of acne severity, and in terms of patients' tolerance. Therefore, it can be concluded that MB in the nanoemulgel form is a promising treatment approach for acne, and can be further experimented in the treatment of other dermatological diseases.

Observation on the effects of 595- nm pulsed dye laser and 755- nm long-pulsed alexandrite laser on sequential therapy of infantile hemangioma

BACKGROUND

Infantile hemangioma (IH) can lead to severe complications. The 595-nm pulsed dye laser is poorly effective on thick and deep IH. Long-pulsed alexandrite laser has the proper wavelength of 755 nm and a relatively deep penetration. Thus, this may be a safe and effective treatment method for relatively deep or thick IH.

AIMS AND OBJECTIVES

This study aims to determine whether 595-nm pulsed dye laser and 755-nm long-pulsed alexandrite laser in sequential therapy are safer and more effective for relatively deep or thick hemangioma.

MATERIALS AND METHODS

This was a prospective study. A total of 194 infantile IH patients (thickness greater than 2 mm and less than 8 mm) were randomly divided into two groups: control group (treated using 595-nm pulsed dye laser) and experimental group (treated by sequential therapy with 755-nm long-pulsed alexandrite laser and 595-nm dye laser).

RESULTS

The control group had a total effective rate of 36.1%, while the experimental group had a total effective rate of 76.3%. Enumeration data were compared by X² -test. The results were considered statistically significant at P < .05.

CONCLUSION

Sequential therapy with 755-nm pulsed dye laser and 595-nm long-pulsed alexandrite laser is a safe and effective treatment approach for relatively deep or thick hemangioma.

The influence of morphological distribution of melanin on parameter selection in laser thermotherapy for vascular skin diseases

Port wine stains (PWSs) are congenital vascular malformations that progressively darken and thicken with age. Currently, laser therapy is the most effective way in clinical management of PWS. It is known that skin pigmentation (melanin content) affects the radiant exposure that can be safely applied to treat PWS. However, the effect of melanin distribution in the epidermis on the maximum safe radiant exposure has not been studied previously. In this study, 10 different morphological distributions of melanin were proposed according to the formation and migration characteristics of melanin, and the two-scale heat transfer model was employed to investigate the influence of melanin distribution on the threshold radiant exposure of epidermis and blood vessels. The results show that melanin distributions do have a strong effect on laser parameter selection. When uniform melanin distribution is assumed, the threshold radiant exposure to damage a typical PWS blood vessel (50 μm diameter) is 8.62 J/cm² lower than that to injure epidermis. The optimal pulse duration is 1-5 ms for a typical PWS blood vessel of 50 μm when melanin distribution is taken into consideration. PWS blood vessels covered by non-uniformly distributed melanin are more likely to have poor response to laser treatment.

The Role of Laser Speckle Imaging in Port-Wine Stain Research: Recent Advances and Opportunities

Here, we review our current knowledge on the etiology and treatment of port-wine stain (PWS) birthmarks. Current treatment options have significant limitations in terms of efficacy. With the combination of 1) a suitable preclinical microvascular model, 2) laser speckle imaging (LSI) to evaluate blood-flow dynamics, and 3) a longitudinal experimental design, rapid preclinical assessment of new phototherapies can be translated from the lab to the clinic. The combination of photodynamic therapy (PDT) and pulsed-dye laser (PDL) irradiation achieves a synergistic effect that reduces the required radiant exposures of the individual phototherapies to achieve persistent vascular shutdown. PDL combined with anti-angiogenic agents is a promising strategy to achieve persistent vascular shutdown by preventing reformation and reperfusion of photocoagulated blood vessels. Integration of LSI into the clinical workflow may lead to surgical image guidance that maximizes acute photocoagulation, is expected to improve PWS therapeutic outcome. Continued integration of noninvasive optical imaging technologies and biochemical analysis collectively are expected to lead to more robust treatment strategies.

Intraoperative, real-time monitoring of blood flow dynamics associated with laser surgery of port wine stain birthmarks

BACKGROUND AND OBJECTIVE

Port-wine stain (PWS) birthmarks affect ∼22 million people worldwide. After several treatment sessions, complete disappearance of the PWS occurs in only ∼10% of treated patients. There is a need to develop a new strategy to improve the efficacy of each treatment session and the overall treatment outcome. The study objective was to determine how intraoperative measurements of blood flow correlate with treatment response assessed several weeks post treatment.

STUDY DESIGN/MATERIALS AND METHODS

We employed Laser Speckle Imaging (LSI) to measure intraoperative blood-flow dynamics. We collected data from 24 subjects undergoing laser therapy for facial PWS birthmarks. Photographs were taken before treatment and at a follow-up visit, and analyzed by two expert observers.

RESULTS

Intraoperative LSI enables real-time monitoring of blood-flow dynamics in response to laser treatment and can inform clinicians on the need for focused re-treatment. The degree of PWS blanching achieved is positively correlated with the log-transformed acute blood-flow reduction (P = 0.022).

CONCLUSION

LSI is a simple, intraoperative monitoring tool during laser therapy of PWS birthmarks. LSI provides a single value for blood flow that correlates well with the degree of blanching achieved with laser therapy.

Treatment of port-wine stains with flash lamp pumped pulsed dye laser on Indian skin: a six year study

Context:

Port-wine stain (PWS) is one of the commonly encountered congenital cutaneous vascular lesions, with an equal sex distribution. Pulsed dye lasers (PDL) have revolutionized the treatment of both congential and acquired cutaneous vascular lesions. The pulsed dye lasers owing to its superior efficacy and safety profile have become the gold standard for the management of port-wine stains.

Aims:

To evaluate the efficacy and side effects of pulsed dye laser for the management of Port-wine stain on Indian skin.

Materials and Methods:

Seventy five patients of Fitzpatrick skin types IV&V with PWS underwent multiple treatments with PDL (V beam-Candela) over a period of six years at monthly intervals. Laser parameters were wavelength 595nm, spot sizes 7-10mm, fluence 6-12 j/cm2, pulse duration 0.45-10ms, along with cryogen cooling. Serial photographs were taken before and after every session. Clinical improvement scores of comparable photographs using a quartile grading (o=<20%, 1=21-40%, 2=41-60%, 3=61-80%, 4=>80%) were judged independently by two dermatologists after the series of treatment. Minimum number of treatments was 6 and maximum 17. They were followed up at six monthly intervals to observe re darkening of PWS.

Results:

No patient showed total clearance.Grade3 improvement was observed in 70 % of children and 50% of adults after 8-10 sessions. Children showed better and faster response than adults. Thirty percent of patients developed post inflammatory hyper pigmentation which resolved over a period of six to eight weeks. Two patients had superficial scarring due to stacking of pulses. None of the patients showed re darkening of PWS till now.

Conclusion:

Pulsed dye laser is an effective and safe treatment for port-wine stain in Indian skin.

Beneficial effects of early treatment of infantile hemangiomas with a long-pulse Alexandrite laser

BACKGROUND AND OBJECTIVE

There is an increasing interest in treating vascular lesions with a long-pulse Alexandrite laser. However, it is difficult to search information in the literature about infantile hemangiomas (IH) treated with long-pulse Alexandrite laser. This article aims to determine whether 755 nm long-pulse Alexandrite laser is effective and safe for early intervention of IH and provides some new data on this issue.

MATERIALS AND METHODS

This is a retrospective study of 48 infants with IH treated with long-pulse Alexandrite laser during a 1.5-year period. Patients received a series of 1-7 treatment sessions with long-pulse Alexandrite laser at settings of 3 milliseconds pulse duration, 6-8 mm spot, 45-70 J/cm(2) fluences, and with dynamic cooling device (DCD) spray duration of 90 milliseconds and delay of 80 milliseconds, given at 4- to 6-week intervals.

RESULTS

This study demonstrated that IH responded favorably to the treatment of a long-pulse Alexandrite laser while accompany with relatively few complications. The difference between the original untreated and post-treatment scores of all IH and two subgroups were statistically significant, respectively (P < 0.01). The difference of the degree of improvement between the two subgroups was not significant (P > 0.05). It was observed that IH on the trunk and extremities improved more effectively and more quickly than those on the face, neck, and perineum. Besides, age at the first treatment, the sex of the patients and the presence of proliferation were not significantly correlated with the degree of improvement. Adverse effects were seen in 11 patients (22.91%): blistering (n = 9), marked edema and erosion without subsequent residual scarring (n = 1), and hypopigmentation (n = 1), which improved gradually with time. Fortunately, there was no incidence of scarring or ulceration in this case series of IH.

CONCLUSIONS

It was clinically effective and safe for early treatment of IH, including the thick/deep ones, with a long-pulse Alexandrite laser, which indicated be able to reduce the possibility that the IH will reach its full size. In this way it can prevent several complications connected to the rapid proliferation of IH.

TRASER--Total Reflection Amplification of Spontaneous Emission of Radiation

Background and Objective

Light and lasers in medical therapy have made dramatic strides since their invention five decades ago. However, the manufacture of lasers can be complex and expensive which often makes treatments limited and costly. Further, no single laser will provide the correct parameters to treat all things. Hence, laser specialists often need multiple devices to practice their specialty. A new concept is described herein that has the potential to replace many lasers and light sources with a single ‘tunable’ device.

Study Design/Material and Methods

This device amplifies spontaneous emission of radiation by capturing and retaining photons through total internal reflection, hence the acronym Total Reflection Amplification of Spontaneous Emission of Radiation, or TRASER.

Results

Specific peaks of light can be produced in a reproducible manner with high peak powers of variable pulse durations, a large spot size, and high repetition rate.

Conclusion

Considering the characteristics and parameters of Traser technology, it is possible that this one device would likely be able to replace the pulsed dye laser and many other light based systems.

An overview of clinical and experimental treatment modalities for port wine stains

Port wine stains (PWS) are the most common vascular malformation of the skin, occurring in 0.3% to 0.5% of the population. Noninvasive laser irradiation with flashlamp-pumped pulsed dye lasers (selective photothermolysis) currently comprises the gold standard treatment of PWS; however, the majority of PWS fail to clear completely after selective photothermolysis. In this review, the clinically used PWS treatment modalities (pulsed dye lasers, alexandrite lasers, neodymium:yttrium-aluminum-garnet lasers, and intense pulsed light) and techniques (combination approaches, multiple passes, and epidermal cooling) are discussed. Retrospective analysis of clinical studies published between 1990 and 2011 was performed to determine therapeutic efficacies for each clinically used modality/technique. In addition, factors that have resulted in the high degree of therapeutic recalcitrance are identified, and emerging experimental treatment strategies are addressed, including the use of photodynamic therapy, immunomodulators, angiogenesis inhibitors, hypobaric pressure, and site-specific pharmaco-laser therapy.

An overview of three promising mechanical, optical, and biochemical engineering approaches to improve selective photothermolysis of refractory port wine stains

During the last three decades, several laser systems, ancillary technologies, and treatment modalities have been developed for the treatment of port wine stains (PWSs). However, approximately half of the PWS patient population responds suboptimally to laser treatment. Consequently, novel treatment modalities and therapeutic techniques/strategies are required to improve PWS treatment efficacy. This overview therefore focuses on three distinct experimental approaches for the optimization of PWS laser treatment. The approaches are addressed from the perspective of mechanical engineering (the use of local hypobaric pressure to induce vasodilation in the laser-irradiated dermal microcirculation), optical engineering (laser-speckle imaging of post-treatment flow in laser-treated PWS skin), and biochemical engineering (light- and heat-activatable liposomal drug delivery systems to enhance the extent of post-irradiation vascular occlusion).

Treatment of angiokeratoma of Fordyce with pulsed dye laser

BACKGROUND

Angiokeratomas of Fordyce are typically asymptomatic vascular lesions characterized by blue-to-red papules with a scale surface, most often located on the scrotum. Although considered benign, the lesions may bleed, either spontaneously or secondary to rupture, leading to patient anxiety and social embarrassment.

OBJECTIVE

The objective was to determine the safety and effectiveness of 585-nm pulsed dye laser for the treatment of angiokeratomas of Fordyce.

METHODS

Twelve patients with Fitzpatrick skin type II to IV were treated for angiokeratomas of Fordyce with pulsed dye laser (5.5-8.0 J/cm(2)) in two to six sessions. Lesion clearance was evaluated by two specialists on the basis of digital photographs taken before the first treatment and 2 months after the last treatment.

RESULTS

Seven patients had an excellent response (clearance rating 75%-100%) and five patients had a good response (clearance rating 50%-75%). Transient purpura and pain were present in all patients. Bleeding during treatment occurred in five patients. There were no permanent side effects.

CONCLUSION

Pulsed dye laser is effective and safe for the treatment of angiokeratoma of Fordyce, with minimum side effects, providing an additional nonablative therapeutic option.

[Port wine stains and laser treatments]

Port wine stains correspond to cutaneous congenital capillary dysplasias and are undergoing broad clinical appearances as far as size, colour, and anatomical areas are concerned together with several possible associations to other vascular pathology. Laser treatment started by the end of the 70's with, at that time moderate scientific production, followed by a very "explosive" period till mid 90's, leading to a progressive decrease till today. Therefore, everything has been reported several times and, in some occasions with some kind of artlessness and/or without follow-up. Author will try in this paper to report a 25 years experience, with as much objectivity as possible.

The effect of ambient temperature on capillary vascular malformations

BACKGROUND

Following pulsed dye laser (PDL) treatment of capillary vascular malformations (CMs), the capillaries left behind tend to be smaller and deeper. The PDL is most effective against capillaries over 50 microm, suggesting that clearance of CM could be improved by inducing capillary vasodilation of the smaller remaining capillaries. However, there are reduced perivascular nerves within CMs, implying that autonomic innervation to these capillaries may be abnormal.

OBJECTIVES

To investigate whether CM capillaries will vasodilate in response to autonomic stimulation by raising ambient temperature.

METHODS

Ten patients with untreated CMs and nine with previously laser-treated CMs were studied as ambient temperature was increased from 20 degrees C to 28 degrees C. The following measurements were taken at 2 degrees C intervals: skin blood flow (SBF); capillary diameter and depth; CM colour; and skin and core temperatures.

RESULTS

All the subjects studied demonstrated superficial capillary vasodilation and increased SBF as the ambient temperature was raised from 20 degrees C to 28 degrees C. Mean+/-SEM capillary diameter increased from 66+/-7 microm to 110+/-13 microm (P<0.001) in the untreated group, compared with an increase from 28+/-5 microm to 70+/-14 microm (P<0.001) in the treated group. Mean+/-SEM SBF increased from 427.2+/-98.2 perfusion units (PU) to 580.9+/-92.7 PU (P<0.01) in the untreated group, compared with an increase from 201.3+/-28.4 PU to 458.1+/-53.7 PU (P<0.05) in the treated group.

CONCLUSIONS

Superficial capillary vasodilation within CM is achievable by raising ambient temperature, including in those patients resistant to PDL treatment, potentially allowing further clearance of these lesions.

The Effect of Varying Pulse Duration, Wavelength, Spot Size, and Fluence on the Response of Previously Treated Capillary Vascular Malformations to Pulsed-Dye Laser Treatment

Modern lasers allow different parameters to be altered in an effort to gain further improvement in otherwise resistant capillary vascular malformations (CMs). The aim of this study was to examine the effect of changing the pulse duration, wavelength, spot size, and fluence on the color and capillary architecture of 585-nm pulsed-dye, laser-resistant CMs. Eighteen patients were assessed with a depth measurement videomicroscope (DMV) before and after 12 test patches with ScleroPlus and V-Beam lasers at specified parameters. In the majority of the test patch areas, there was little improvement after treatment. However, 44% of patients had greater than 75% clearance in at least 1 test patch site. This study demonstrates that both lasers can achieve further lightening in 585 nm 0.45 msec pulsed-dye laser-resistant CMs. However, in CMs consisting of small-diameter deep vessels, further improvement is unlikely.

Laser treatment of leg veins

The development of lasers using deeper-penetrating, near-infrared wavelengths with millisecond pulse durations and skin-cooling methods has produced safer and more predictable results for the treatment of leg veins less than 1 mm in diameter and depth. Recent prospective studies of the near-infrared lasers show comparable efficacy and side effect profiles to those observed with sclerotherapy. Treatment of reticular and varicose veins is effective with these wavelengths but is limited by patient discomfort when compared with sclerotherapy. Visible light lasers (such as the pulsed dye and KTP) and intense pulsed-light sources are reproducibly effective only for superficial, nonarborizing pink-to-red telangiectasia, in the absence of points of proximal reflux. Because most lower-extremity vascular ectasias comprise a heterogeneous group of vessel sizes and depths, many patients achieve the best results using a combination of techniques. This article reviews the fundamentals of laser tissue interactions for the treatment of leg veins and details the recent clinical experience with the newer near-infrared devices.

Concomitant treatment of psoriasis of the hands and feet with pulsed dye laser and topical calcipotriol, salicylic acid, or both: A prospective open study in 41 patients

BACKGROUND

Psoriasis of the hands and feet is a chronic disease which is often resistant to the usual topical therapies. It has considerable morbidity and seriously affects the quality of life of patients.

OBJECTIVE

We sought to prospectively evaluate the efficacy and safety of pulsed dye laser (PDL) treatment of psoriasis of the hands and feet.

METHODS

In all, 41 patients with therapy-resistant psoriasis of the hands and feet were treated once every 4 to 6 weeks with PDL at 585-nm wavelength, 450-microsecond pulse duration, 7-mm spot diameter, and 5- to 6.5-J/cm2 fluence. Calcipotriol ointment and salicylic acid 5% to 10% ointment were used as keratolytic agents. Treatment efficacy was evaluated by blinded comparison of photographs of the lesions taken before and after PDL treatment in each patient.

RESULTS

A good to very good improvement in the lesions was observed in 76% of the patients after treatment. An average duration of remission was 11 months. Side effects were transient purpura, moderate discomfort during the treatment, transient hyperpigmentation or hypopigmentation, and incidental transient crustae.

LIMITATIONS

This was an open prospective study with a limited number of patients who were concomitantly treated with calcipotriol and salicylic acid ointment. Patients with photointolerance, on medication with phototoxic or photoallergic drugs, and with widespread psoriasis were excluded.

CONCLUSIONS

Concomitant treatment with PDL and topical calcipotriol, salicylic acid, or both was a satisfactory modality for treating psoriasis of the hands and feet. There was a subjective improvement in the symptoms and quality of life in all patients.

Study of patient-reported morbidity following V-beam pulsed-dye laser treatment of port wine stains

The V-beam pulsed-dye laser (PDL) (595 nm) has gained popularity in the treatment of port wine stains (PWS). It uses longer pulse durations than the standard flashlamp-pumped pulsed-dye laser (FPDL) (585 nm) and has an in-built cooling system to protect the epidermis. This should, theoretically, reduce the treatment-associated side effects, including discomfort. The aim of this questionnaire-based study was to confirm the clinical impression that V-beam PDL is well tolerated. The results were compared with a historical group of 62 PWS patients treated with FPDL. Fifty-one patients took part in the current study. Only 35.7% (vs. 81% in the historical comparison group) required topical anaesthetic prior to laser treatment. A shortening in the duration of bruising (8 vs. 10 days) and of symptoms such as burning and tightness (3 vs. 10 days) was recorded. Lifestyle change after treatment was recorded by fewer patients (39 vs. 57%). We conclude that V-beam PDL is better tolerated than FPDL when used at therapeutic levels in patients with PWS.

Treatment of Port Wine Stains with Intense Pulsed Light: A Prospective Study

BACKGROUND

Recent studies have shown that intense pulsed light can be useful in treating port wine stains that were resistant to previous pulsed dye laser therapy. Asian persons with high epidermal melanin context can be at a higher risk of complication.

OBJECTIVE

The aim of this study was to conduct a prospective trial to assess the efficacy and complication of intense pulsed light in the treatment of port wine stains in Chinese patients.

METHODS

Twenty-two Chinese patients with port wine stains without previous treatment were recruited to receive intense pulsed light source therapy for five to seven treatments at intervals of 3 to 4 weeks. Patient demographics, skin type, characteristics of port wine stains including color and location, treatment parameters, degree of pain caused by intense pulsed light treatment, percentage of clearing, and treatment complications were recorded and entered into a database. A questionnaire was conducted to assess the influence of treatment on daily activity and the intensity of pain experienced during treatment.

RESULTS

There were 17 female and 5 male patients. Their ages ranged from 6 to 45 years with a mean age of 21.8+/-10.1 years. More than 90% of patients had more than 25% of clearing and the majority of patients (50%) had 25% to 50% of clearing. Although 40% of the patients showed more than 50% clinical clearance, 9% of the patients were able to achieve more than 75% clearing. The only 2 patients with less than 25% clearing had nodular port wine stains and no patient was able to achieve complete clearing. The procedures were well tolerated with a mean pain score of 2.1+/-0.9 and the treatment had no influence on daily activity. One patient developed blisters and 6 patients had swelling for more than 24 hr that all resolved within 1 week without leaving permanent marks. They have been followed up from 12 to 27 months and there was no long-term complication.

CONCLUSION

Intense pulsed light can be effective in treating port wine stains in Asian patients. In experienced hands, complications can be low and should be considered as one of the therapeutic options.

Laser Treatment of Cutaneous Vascular Anomalies

BACKGROUND

Lasers and light-based therapy have been used to treat port-wine stains and hemangiomas for the past two decades.

METHODS AND RESULTS

Laser treatment produces dramatic clearing of port-wine stains with minimal scarring or epidermal damage, minimizes hypertrophy of lesions, decreases the risk of bleeding from pyogenic granlomas, and reduces the associated psychosocial morbidity. Lasers are used to halt the proliferation of the superficial component of hemangiomas, reduce the mass of the lesions, and to treat the vascular ectasia as well as the atrophic scarring that develops following involution.

CONCLUSION

Laser therapy provides a safe and effective modality with low morbidity for cutaneous vascular anomalies.

A pilot investigation to subjectively measure treatment effect and side-effect profile of non-ablative skin remodeling using a 532 nm, 2 ms pulse-duration laser

BACKGROUND AND OBJECTIVE

Carbon dioxide laser skin resurfacing has become a standard treatment for wrinkles and sun-damaged skin. This ablative treatment, however, is associated with undesirable complications and long recovery times. A growing body of evidence suggests that dermal inflammation and subsequent collagen formation can be stimulated without removal of the epidermis, raising the possibility of effective non-ablative skin remodeling for mild to moderately photodamaged skin.

MATERIALS AND METHODS

This preliminary study was performed to evaluate the safety and subject satisfaction of non-ablative skin remodeling using a 532 nm, 2 ms pulse-duration, frequency-doubled Nd:YAG laser. Subjects with mild-to-deep lip wrinkles and mild-moderate acne scarring were treated one half of their lip (wrinkles) or cheek (acne scarring), leaving the other side as an untreated control. Subjects were treated at 3-6 week intervals for an average of three treatments. Subjective assessment of improvement was estimated by subject self-evaluation of the percentage improvement over baseline, and a blinded observer attempted to identify the treated side on physical examination.

RESULTS

Subjective assessment revealed an average improvement of 51.4% and 53.6% for upper lip wrinkles and facial acne scarring, respectively. Side effects were limited to transient erythema that resolved over 0.25-2 hours following treatment.

CONCLUSIONS

These results demonstrate that non-ablative treatment with the 532 nm, 2 ms pulse-duration Nd:YAG laser results in subjective improvement of rhytides and acne scarring, with a high safety profile.

Both the flashlamp-pumped dye laser and the long-pulsed tunable dye laser can improve results in port-wine stain therapy

BACKGROUND

At present, laser therapy of port-wine stains (PWS) using the flashlamp-pumped dye laser (FPDL) at 450 micros is accepted as the optimal approach. A few years ago, a new long-pulsed tunable dye laser (LPTDL, 1.5 ms) was introduced for the treatment of leg veins.

OBJECTIVES

To investigate the efficacy and side-effects of FPDL vs. LPTDL therapy of PWS.

METHODS

Sixty-two patients with untreated PWS underwent test treatments with the FPDL (585 nm; 7-mm spot size; 5.75--7.0 J cm(-2) fluence) and LPTDL (585, 590, 595, 600 nm; 5-mm spot size; 11--20 J cm(-2) fluence). With the LPTDL, the epidermis was additionally cooled (Spray cooling device). The fading was evaluated clinically 6 weeks after the test treatments.

RESULTS

Optimal fading was achieved by the LPTDL (> or = 585 nm) in 30 patients and by the FPDL in 12 patients. No difference was found in 20 patients. At 585 nm, the lasers worked equally well in 12 (FPDL) and 13 (LPTDL) patients, respectively. Results were independent of the localization of the PWS and of the patient's age. In spite of the longer pulse duration, the LPTDL treatment did not result in more side-effects as long as sufficient cooling was provided.

CONCLUSIONS

The results provide evidence that wavelengths longer than 585 nm can increase the efficacy of treatment in some PWS. Owing to the reduced light absorption by haemoglobin at longer wavelengths and consequently increased depth of the vascular injury, larger vessels can be damaged more adequately using an increased fluence. The LPTDL at 585 nm seemed to be slightly superior to the FPDL, while accepting that due to technical reasons the laser parameters were not directly comparable. Availability of both lasers increases the therapeutic possibilities in PWS.

Histologic evaluation of skin damage after overlapping and nonoverlapping flashlamp pumped pulsed dye laser pulses: A study on normal human skin as a model for port wine stains

BACKGROUND AND OBJECTIVE

In the treatment of port wine stains (PWS) with the flashlamp pumped pulsed dye laser (FPPDL), no consensus exists about overlapping of pulses. The advantage of overlapping pulses is homogeneous lightening of the PWS; the risk is redundant tissue damage. The aim of this study was to determine the histopathologic effect on human skin of pulsed dye laser pulses with various degrees of overlap, with normal human skin as a model for PWS.

STUDY DESIGN/MATERIALS AND METHODS

Eighteen healthy white volunteers were irradiated with pulsed dye laser pulses with increasing radiant exposure and with different degrees of overlap. Biopsy samples were taken and histologically analysed.

RESULTS

Overlapping of pulses on normal human skin enhances depth of vascular damage with approximately 30%. Adjacent pulses also show this effect. We found no histologic signs of serious damage to epidermis or dermal connective tissue by using radiant exposure levels of 6-8 J/cm(2), regardless of pulse application.

CONCLUSIONS

Reasoning that the mechanism of tissue injury is comparable for normal and PWS skin, we conclude that it is safe to treat PWS with overlapping FPPDL pulses to achieve homogeneous lightening.

Photothermal coagulation of blood vessels: a comparison of high-speed optical coherence tomography and numerical modelling

Optical-thermal models that can accurately predict temperature rise and damage in blood vessels and surrounding tissue may be used to improve the treatment of vascular disorders. Verification of these models has been hampered by the lack of time- and depth-resolved experimental data. In this preliminary study, an optical coherence tomography system operating at 4-30 frames per second was used to visualize laser irradiation of cutaneous (hamster dorsal skin flap) blood vessels. An argon laser was utilized with the following parameters: pulse duration 0.1-2.0 s, spot size 0.1-1.0 mm, power 100-400 mW. Video microscopy images were obtained before and after irradiations, and optical-thermal modelling was performed on two irradiation cases. Time-resolved optical coherence tomography and still images were compared with predictions of temperature rise and damage using Monte Carlo and finite difference techniques. In general, predicted damage agreed with the actual blood vessel and surrounding tissue coagulation seen in images. However, limitations of current optical-thermal models were identified, such as the inability to model the dynamic changes in blood vessel diameter that were seen in the optical coherence tomography images.

The treatment of port wine stains with a dye laser: a study of 644 patients

Between June 1989 and December 1996, the flashlamp pumped pulsed dye laser was used to treat port wine stains (PWS) in 644 patients, age range 3 months-93 years (mean 21). The efficacy of the treatment was assessed after more than one year of follow-up. Each factor that might affect the efficacy was then evaluated statistically. Broad lesions required more laser treatments than narrow lesions and clearing tended to start from the periphery of the lesion, indicating the three-dimensional depth of the broader PWS. Patients who had been given previous treatments such as argon laser required about two more laser treatments than those who had not, but there were no clear differences in the efficacy of dye laser treatment between the two groups.

The use of lasers in dermatology

There are now a range of lasers capable of effective treatment of vascular, pigmented and other skin lesions with a high degree of selectivity. Understanding the complex interactions between laser irradiation and often diverse lesion morphology is the key to determining the appropriateness of treatment.

The pulsed dye laser for cutaneous vascular and nonvascular lesions

The pulsed dye laser was originally developed for the treatment of vascular lesions, especially hemangiomas and port-wine stains. The central concept of pulsed-dye laser is to preserving the epidermis by allowing hemoglobin to be more precisely targeted within lesions. More recently, the pulsed dye laser has also been used in the treatment of a wide spectrum of nonvascular lesions. Because of its safety profile, and its selectivity in targeting lesions, therapists can comfortably treat a wide variety of lesions in all age groups and anatomic sites.

Treatment of 'angiomas': a modern commentary

The terminology and classification of vascular birthmarks has been simplified and clarified since 1951. Where treatment is indicated, this also has changed from radiotherapy being the treatment of choice to now having a range of therapeutic options including corticosteroids, alpha-interferon, alginate and hydrocolloid dressings, antibiotics, laser and surgery. Another important aspect of the management of haemangiomas is the recognition that certain patterns can be associated with other abnormalities.

Elucidating the pulsed-dye laser treatment of sebaceous hyperplasia in vivo with real-time confocal scanning laser microscopy

BACKGROUND

Several case reports document successful treatment of sebaceous hyperplasia with the pulsed-dye laser. Moreover, noninvasive real-time confocal laser scanning microscopy elucidates the vascular nature of these lesions and their pathophysiologic response to treatment mediated by vessel coagulation.

METHODS

Ten patients with 29 lesions of sebaceous hyperplasia were treated with 3 stacked 5-mm pulses of the 585-nm pulsed-dye laser at fluences of 7 or 7.5 J/cm(2). Confocal imaging was performed before and immediately after treatment, as well as at 2, 4, and 8 weeks of follow-up.

RESULTS

The great majority of lesions responded to one treatment, with complete disappearance in 28%, decrease in diameter in 66%, and flattening in 93%. Although 28% recrudesced after initial involution, only 7% recurred completely. Three lesions became eroded or crusted, and 7 experienced cutaneous depressions before complete healing, but no scarring or pigmentary side effects were noted. Confocal imaging revealed a prominent "crown" of blood vessels surrounding the sebaceous duct and coagulation of these vessels with pulsed-dye laser treatment. However, the vessels reappeared during follow-up, and no noticeable morphologic changes in the sebaceous duct were noted.

CONCLUSION

Vascular targeting of sebaceous hyperplasia can be monitored with real-time reflectance confocal microscopy. Most sebaceous hyperplasia regresses after one treatment with 3 stacked pulses of the 585-nm pulsed-dye laser. Whether this response is due to temporary ischemia induced by selective vessel destruction or nonspecific thermal diffusion beyond the vessels from pulse stacking has not been determined.

Time-sequence histologic imaging of laser-treated cherry angiomas with in vivo confocal microscopy

OBJECTIVE

To chronicle the pathophysiologic changes that occur subsequent to laser treatment of vascular lesions, we used a confocal scanning laser microscope that yields high-resolution microscopic images of skin in vivo.

METHODS

Cherry angiomas were treated with the 585-nm flashlamp-pumped pulsed-dye laser (PDL) and the 568-nm continuous-wave krypton laser. Repeated confocal reflectance imaging was performed before and immediately after treatment, as well as after several hours, 1 day, 2 days, 1 week, 2 weeks, 3 weeks, and 4 weeks.

RESULTS

Before treatment, confocal images revealed dilated blood vessels ranging from 10 to 50 microm in caliber, closely spaced at 5 to 50 microm apart. After PDL treatment, amorphous cords of refractile material conformed to the shape of the original vessels, followed by dark nonrefractile spaces where the vessels once were. Inflammation and necrosis ensued, with eventual replacement after 3 weeks by normal-appearing skin. After krypton laser treatment, dark nonrefractile spaces appeared immediately, with subsequent inflammation, necrosis, and eventual healing by 4 weeks.

CONCLUSION

Confocal laser microscopic imaging elucidates the dynamic pathophysiologic events that occur after laser treatment of vascular lesions and has added insight into the different mechanisms of vessel damage induced by the PDL and krypton laser.

Optimal parameters for laser treatment of leg telangiectasia

BACKGROUND AND OBJECTIVE

The optimal parameters for treatment of leg telangiectasia with a pulsed laser are investigated.

STUDY DESIGN/MATERIALS AND METHODS

The Monte Carlo method is used to calculate the light penetration and absorption in the epidermis, dermis, and the ectatic blood vessel. Calculations are made for different diameters and depths of the vessel in the dermis. In addition, the oxygen saturation of the blood vessel, the laser beam diameter, and the laser irradiation profile is varied.

RESULTS

It is found that for vessels with diameters between 0.3 mm and 0.5 mm wavelengths about 600 nm are optimal to achieve selective photothermolysis for the considered damage model. It is also shown that an elliptical laser beam area has advantages compared to a circular beam area for treatment of leg telangiectasia.

CONCLUSIONS

We recommend the treatment of leg telangiectasia with dye laser wavelengths longer than the normally used 577 nm and 585 nm.

Side effects from dermatological laser treatment related to UV exposure and epidermal thickness: a murine experiment with the copper vapor laser

BACKGROUND AND OBJECTIVE

The intention of the present study was to clarify whether UV-exposure prior to laser treatment of albino mouse skin may influence laser-induced side effects and if a possible influence may be explained by epidermal thickening.

STUDY DESIGN/MATERIALS AND METHODS

Albino, hairless mice were irradiated 0, 8, and 22 consecutive times with simulated solar UV (1.4 J/cm2 per treatment). Subsequently, two areas on the back of the mice (1.26 cm2 each) were treated with a copper vapor laser that was connected to a Hexascan. The beam diameter was 1 mm, pulse duration 200 msec, and intensities 0.6 W, 0.8 W, and 1.0 W. Laser-induced wounds, scars, and histologically evaluated fibrosis were evaluated.

RESULTS

We found that mice irradiated with UV before laser treatment developed smaller wounds, smaller texture change areas, and less fibrosis as compared with nonirradiated control groups, and significant, negative correlations were demonstrated between epidermal thicknesses (stratum corneum, the cellular part of epidermis, and the entire epidermis) and laser-induced skin reactions. A dose response was obtained between laser intensities and laser-induced skin reactions, which tended to be more severe in the cranial back location as compared with the caudal back location. Epidermal layers increased significantly after eight consecutive times of UV irradiation and increased to a steady level after 22 times of irradiation.

CONCLUSION

We conclude that UV exposure prior to laser treatment of albino mice reduced laser-induced side-effects, which could be explained by increased epidermal thickening. Variations in epidermal thickness might thus contribute to variations in clinical response to dermatological laser treatment with the copper vapor laser.

Modeling laser treatment of port wine stains with a computer-reconstructed biopsy

BACKGROUND AND OBJECTIVE

The efficacy of laser treatment of port wine stains (PWS) has been shown to be highly dependent on patient-specific vasculature. The effect of tissue structure on optical and thermal mechanisms was investigated for different pulse durations by using a novel theoretical model that incorporates tissue morphology reconstructed tomographically from a PWS biopsy.

STUDY DESIGN/MATERIALS AND METHODS

An optical-thermal numerical model capable of simulating arbitrarily complex, three-dimensional tissue geometries was developed. The model is comprised of (1) a voxel-based Monte Carlo optical model, (2) a finite difference thermal model, and (3) an Arrhenius rate process calculation to predict the distribution of thermal damage. Simulations based on previous computer-based reconstruction of a series of 6 microm sections from a PWS biopsy were performed for laser pulse durations (taup) of 0.5, 5.0, and 10.0 ms at a wavelength of 585 nm.

RESULTS

Energy deposition rate in the blood vessels was primarily a function of vessel depth in skin, although shading effects were evident. Thermal confinement and selectivity of damage were seen to be inversely proportional to pulse duration. The model predicted blood-specific damage for taup = 0.5 ms, vascular and perivascular damage for taup = 5 ms, and widespread damage in superficial regions for taup = 10 ms. The effect of energy deposition in the epidermis was most pronounced for longer pulse durations, resulting in increased temperature and extent of damage.

CONCLUSION

Pulse durations between 0.5 and 5 ms are likely optimal for the PWS analyzed. The incorporation of a tomographically reconstructed PWS biopsy into an optical-thermal model represents a significant advance in numerical modeling of laser-tissue interaction.

Simultaneous irradiation and imaging of blood vessels during pulsed laser delivery

BACKGROUND AND OBJECTIVE

Simultaneous irradiation and viewing of 10-120 microm cutaneous blood vessels were performed to investigate the effects of 2-micros 577-nm dye laser pulses.

STUDY DESIGN/MATERIALS AND METHODS

A modified scanning laser confocal microscope recorded vessel response to different radiant exposures (J/cm2). Probit analysis determined the 50% probability ("threshold") radiant exposure necessary to cause embolized or partly occluding coagula, coagula causing complete blood flow stoppage, and hemorrhage.

RESULTS

A statistically significant difference in the threshold radiant exposure existed for each damage category for blood vessels 10-30 microm in diameter, but not for larger vessels. For vessels over 60 microm, complete flow stoppage was unattainable; increasing laser pulse energy produced hemorrhage. In larger vessels, coagula often were attached to the superficial vessel wall while blood flowed underneath. Monte Carlo optical and finite difference thermal modeling confirmed experimental results.

CONCLUSION

These results provide insight into the role of pulse duration and vessel diameter in the outcome of pulsed dye laser irradiation.

Cutaneous lupus erythematosus-treatment with pulsed dye laser

Because of its vascular selectivity, the flashlamp-pumped pulsed dye laser (585 nm) is efficacious in the treatment of vascular lesions and is successfully used for the treatment of port-wine stains and haemangiomas in children. Based on the encouraging results with these cutaneous vascular disorders, the cutaneous lesions of patients with lupus erythematosus (LE) have now also been treated with the pulsed dye laser. Cutaneous lesions in lupus erythematosus are often difficult to treat with readily available local therapeutic methods. We report here on a group of 12 patients whose LE lesions were treated with the pulsed dye laser. In 10 patients, the LE was limited to the skin, while two patients had systemic LE (SLE). Even in the two patients with SLE, a significant improvement of skin lesions was achieved. After a mean number of 51 laser sessions, a median clearance rate of 70% was attained for nine patients. In one case, the laser treatment failed to clear the lesions. Two patients did not show any visible improvement of the lesions, but pain and itching were significantly reduced. There were few side-effects. No prolonged laser-induced scarring occurred and in only two patients was hyperpigmentation seen, which had resolved completely after 4 and 5 months, respectively. During a median follow-up of 7 months (range: 3-32 months), only one patient (after a complete clearance of the skin lesions) had a small relapse. In summary, the pulsed dye laser is an effective therapy for the treatment of superficial skin lesions in LE.