Action spectrum of vascular specific injury using pulsed irradiation

It has been clearly demonstrated that cutaneous blood vessels will be selectively damaged by a laser whose wavelength matches one of the three absorption spectral peaks of the chromophore, oxyhemoglobin, for example, 577 nm. A restriction in the application of this wavelength for the treatment of benign cutaneous vascular tumors, such as portwine stains, has been the penetration depth of 577 nm irradiation of approximately 0.5 mm from the dermal epidermal junction (DEJ). This study was undertaken to establish whether it was possible to increase the penetration depth from 0.5 mm by changing the wavelength to beyond 577 nm in albino pig skin. Results from this study confirm that penetration depth increases from 0.5 to 1.2 mm by changing the wavelength from 577 to 585 nm at 4 J/cm2, while maintaining the same degree of vascular selectivity as that previously described after 577 nm irradiation. This occurred in spite of a mismatch in the wavelength between 585 nm and the oxyhemoglobin absorption peak of 577 nm. Unlike 585 nm irradiation and in contrast with theoretical predictions, 590 nm laser light did not penetrate as deeply as 585 nm. Not only was there a reduction in the penetration depth of the laser beam from 1.2 mm at 585 nm to 0.8 mm at 590 nm, at 4 J/cm2, but there was also a decrease in vascular selectivity in albino pig skin exposed to 590 nm irradiation.     

Photoelectric quantitative evaluation of argon laser treatment of port wine stains

Sixty patients with port wine stains were treated with the argon laser and graded visually into four subjective categories for changes in skin colour. For objective quantitative evaluation a photoelectric colorimeter was used. Reproducible definition of the lightness of the lesions into numbers was obtained. Differentials in lightness between normal contralateral skin and the portwine stain before and after treatment were quantified for each individual. The objective evaluation revealed a statistically significant difference between the four categories (P<0.05). The best clinical therapeutic effect was found to correlate with only 80–90% blanching. The average lightening obtained was 46.5%. Local heating of portwine stains in 12 patients showed no measurable darkening in the colour of the lesions, whereas the normal contralateral skin reacted with marked reddening. Determination of changes in lightness by photoelectric colorimetry provides an objective, quantitative means to evaluate the effects of laser treatment of port wine stains.     

Ultrastructure: effects of melanin pigment on target specificity using a pulsed dye laser (577 nm)

It has been shown recently that brief pulses of 577 nm radiation from the tunable dye laser are absorbed selectively by oxyhemoglobin. This absorption is associated with highly specific damage to superficial vascular plexus blood vessels in those with lightly pigmented (type I-II) skin. To determine whether pigmentary differences in the overlying epidermis influence this target specificity, we exposed both type I (fair) and type V (dark) normal human skin to varying radiant exposure doses over 1.5-microsecond pulse durations from the tunable dye laser at a wavelength of 577 nm. Using ultrastructural techniques, we found in type I skin that even clinical subthreshold laser exposures caused reproducible alterations of erythrocytes and adjacent dermal vascular endothelium without comparable damage to the overlying epidermis. In contrast, degenerated epidermal basal cells represented the predominant form of cellular damage after laser exposure of type V skin at comparable doses. We conclude that epidermal melanin and vascular hemoglobin are competing sites for 577 nm laser absorption and damage, and that the target specificity of the 577 nm tunable dye laser is therefore influenced by variations in epidermal pigmentation. This finding is relevant to the clinical application of the tunable dye laser in the ablative treatment of vascular lesions. We also found on ultrastructure that the presence of electron-lucent circular structures of approximately 800 A in diameter were observed only at and above clinical threshold doses in those with type I skin and at the highest dose of 2.75 J/cm2 in type V skin. It has been proposed that these structures might be heat-fixed molds of water vapor. Both this and ultrastructural changes of epidermal basal cells demonstrate mechanisms responsible for alteration of tissue after exposure to 577 nm, which are discussed.     

Die Behandlung von Feuermalen mit dem blitzlampengepumpten gepulsten Farbstofflaser Ergebnisse aus 5 Jahren klinischer Erfahrung

BACKGROUND AND OBJECTIVE: Portwine stains are reported to occur in 2.8% of the newborn. Depending on the location and size, portwine stains can be disfiguring and may lead to psychosocial complications. They can be safely and successfully treated with the flashlamp pumped pulsed dye laser (FPDL). Our objective was to evaluate retrospectively the efficacy of the FPDL (450 microseconds, 585 nm, 5 and 7 mm) after five years of clinical experience with this laser. PATIENTS/METHODS: Between 1993-1998 in 961 patients with port-wine stains laser treatment was performed in the department of dermatology of the university of Regensburg. RESULTS: Total clearance of the portwine stain was recorded in 6.9% of the patients. In 40.4% of the patients 75-95% clearance and in 38.5% 50-75% clearance was observed. In 14.2% response was less than 50%. Laser therapy was more effective for lesions of the neck and trunk than for lesions on the head and extremities. Better results were found after laser therapy of light-red or red portwine stains compared to dark red and violaceus portwine stains. In children (less than 3 year old), clearance of more than 75% occurred significantly more often than in older patients. CONCLUSIONS: Since laser treatment in early childhood is more effective than treatment at a later age, a smaller number of treatment sessions is necessary and lower recurrence rates can be expected, laser treatment should be started in early childhood. Side effects were rare after FPDL treatment. This study underlines that the FPDL is a safe and successful treatment for portwine stains with rare side effects. But total clearance can only be reached in a small number of patients.     

Effect of skin temperature on selective vascular injury caused by pulsed laser irradiation

The effect of skin temperature on vascular-specific injury caused by pulsed laser irradiation was examined. Ten healthy human volunteers were exposed to 1.5 microsecond pulses from a dye laser tuned to 577 nm. Compared to normothermic conditions (33 degrees C skin temperature) significantly more laser energy (p less than 0.01) was required to produce grossly visible purpura when the skin was cooled to 20 degrees C or heated to 40 degrees C. Histologically, laser-induced damage was confined to blood vessels at all three skin temperatures studied. At purpura threshold dose, there was intravascular agglutination without extravasation of red blood cells at 20 degrees C whereas at 33 degrees and 40 degrees C there was extravasation of red blood cells.     

Histologic responses of port-wine stains treated by argon, carbon dioxide, and tunable dye lasers. A preliminary report

Although the blue-green argon laser light has been used successfully to treat port-wine stains (PWSs) for many years, it produces substantial epidermal damage. We have previously shown in normal human skin that pulsed yellow tunable dye lasers (577-nm wavelength) can cause highly selective damage to cutaneous microvessels with minimal injury to the overlying epidermis. Pulsed tunable dye lasers also produce selective vascular injury in the abnormal vessels of PWSs, with clinically apparent lightening of the lesions. Both epidermal injury and fibrosis are less severe with this laser treatment than with argon and carbon dioxide laser treatments. Clinical and histologic responses of PWSs treated by argon, CO2, and pulsed yellow dye lasers were compared and followed up for one month in three patients. Although larger and longer-term clinical trials are necessary to fully evaluate this new treatment modality, it appears that pulsed yellow laser radiation offers a more selective, less traumatic, and probably superior form of treatment for PWSs.     

(18) The treatment of portwine stains with the tunable dye laser at 577 nm

The treatment of portwine stains (PWS) by lasers has become established as the treatment of choice in recent years. Most experience has been with the argon laser which emits predominantly at 488 and 514 nm. These wavelengths do not coincide with the absorption maxima of haemoglobin at 415, 542 and 577 nm. Light at 577 nm is particularly well transmitted through the epidermis and selectively absorbed by haemoglobin. We have been treating patients with PWS with a Coherent CR599 argon-pumped continuous wave tunable dye laser emitting at 577 nm.
Seventy-one patients with PWS have been treated in Leeds, mean age 36·9 years, range 11–61 years. Ninety-six per cent had PWS on the face or neck. The majority were treated under local anaesthesia; the longest follow-up has been 42 months.
The minimal blanching method was used¹ with a spot diameter of 1 mm, power range of 0·3 – 0·5 W in most patients, with a pulse duration of 0·5–2 s. Energy fluence was 38–63 J/cm².
Improvement in the treated area from partial to complete paling occurred in 75% with scarring in 5% which was usually atrophic, and minor pigmentary changes in 7%.
These results are comparable with the best series reported from argon laser therapy and confirm the theoretical advantage of treatment with laser light at 577 nm.     

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.     

Ultrastructural changes in human skin after exposure to a pulsed laser

Selective vascular injury following irradiation using a pulsed laser source at 577 nm was examined using ultrastructural methods in the skin of 3 fair-skinned healthy human volunteers. This vascular-specific damage was confined to the papillary dermis. Red blood cells were altered in several ways. As well as an increase in the electron density, configurational distortion modified the normal biconcave forms to ameboid structures. The most interesting finding was the appearance within these altered cells of well-defined circular/oval electron-lucent areas of 800 A diameter, possibly representing a heat-fixed record of steam formation within the red blood cell. In addition, considerable degenerative changes were evident in endothelial cells and pericytes, while mast cells, neutrophils, histiocytes, and fibroblasts as well as collagen bundles immediately surrounding most laser-damaged blood vessels appeared normal.     

Complement activation by pulsed tunable dye laser in normal skin and hemangioma

Pulsed tunable dye laser (577 nm) (PTDL) therapy induces hemoglobin coagulation and tissue necrosis, which is mainly limited to blood vessels. To define whether this treatment activates complement in normal skin and senile hemangioma, we analyzed complement deposition in blood vessels by immunofluorescence. C3 fragments, C8, and C9 were detected with specific polyclonal antibodies. The membrane attack complex of complement (MAC) was demonstrated with a monoclonal antibody which reacts only with a neoantigen of MAC. Amplification of C3 deposition by the alternative pathway was determined on cryostat sections by indirect immunofluorescence with use of C4 deficient guinea pig (GP) serum. Normal skin and hemangiomas from three individuals were studied. In PTLD-irradiated normal skin, the main findings were as follows: 1) C3 fragments, C8, C9, and MAC were deposited in vessel walls; 2) these deposits were not due to denaturation of the proteins since they became apparent only 7 min after irradiation, contrary to immediate deposition of transferrin at the sites of erythrocyte coagulates; 3) the C3 deposits were shown to amplify complement activation by the alternative pathway, a reaction which was specific since tissue necrosis itself did not lead to such amplification; 4) these reactions preceded the local accumulation of polymorphonuclear leucocytes. Tissue necrosis was more pronounced in the hemangiomas. The larger angiomatous vessels in the center of the necrosis did not fix complement significantly. By contrast, complement deposition in the vessels situated at the periphery was similar to that observed in normal skin with one exception: C8, C9, and MAC were detected in some blood vessels immediately after laser treatment, a finding consistent with assembly of the MAC occurring directly without the formation of a C5 convertase. These results indicate that complement is activated in PTDL-induced vascular necrosis, and might be responsible for the ensuing inflammatory response.     

Flashlamp pulsed dye laser and argon-pumped dye laser in the treatment of port-wine stains: a clinical and histological comparison

BACKGROUND: Port-wine stains (PWS) are congenital vascular malformations occurring in 0.3% of children. The pulsed dye laser is a well established treatment for PWS. OBJECTIVES: To compare, clinically and histologically, the effects of the flashlamp pulsed dye laser with the argon-pumped dye laser in the treatment of PWS. METHODS: Thirty patients were treated on two to four test areas with both laser types using different energy fluences. A flashlamp pulsed dye laser with 0.45 ms pulse duration and a spot size of 5 mm was compared with an argon-pumped dye laser, with a spot size of 1 mm delivered with a robotic scanning laser handpiece (Hexascan) and 70-190 ms pulse duration. Both were tuned to 585 nm. Twelve weeks later the degree of lightening was evaluated and biopsies were taken. To count the vessels the skin sections were stained with CD34 using an immunohistochemical technique. The vessels were divided into three groups by diameter (d): d < 10 microm, 10 < or = d < 20 microm, d > or = 20 microm. RESULTS: The clinical results showed a significantly better lightening using the flashlamp pulsed dye laser than with the argon-pumped dye laser. The histological results showed a significant decrease in the number of vessels of diameter larger than 20 microm in treated compared with untreated lesions. We found no histological difference in the number of vessels between the two laser treatments. However, there was a tendency towards more small vessels (diameter < 10 microm) after one treatment with the flashlamp pulsed dye laser compared with untreated PWS. CONCLUSIONS: The flashlamp pulsed dye laser is clinically superior to the argon-pumped dye laser in the treatment of PWS.     

Effect of dye laser pulse duration on selective cutaneous vascular injury

The pulsed dye laser at 577 nm, a wavelength well absorbed by oxyhemoglobin, causes highly selective thermal injury to cutaneous blood vessels. Confinement of thermal damage to microvessels is, in theory, related to the laser exposure time (pulsewidth) on selective vascular injury. This study investigates the effect of 577 nm dye laser pulsewidth on selective vascular injury. Nine Caucasian, normal volunteers received 577 nm dye laser exposures at pulsewidths of 1.5-350 microseconds to their skin. Clinical purpura threshold exposure doses were determined in each volunteer, and biopsies of threshold and suprathreshold doses were examined in each volunteer. The laser exposure dose required to produce purpura increased as pulsewidth increased in all 9 subjects (p less than 0.001). This finding corresponds to laser pulsewidths equal to or exceeding the thermal relaxation times for dermal blood vessels. Histologically, vessel damage was selectively, but qualitatively, different for short vs long pulsewidths. Pulsewidths shorter than 20 microseconds caused vessel wall fragmentation and hemorrhage, whereas longer pulsewidths caused no significant hemorrhage. The purpura noted clinically appears to be due to a coagulum of intralumenal denatured erythrocytes. At 24 h, there was marked vessel wall necrosis at all pulsewidths. The short pulsewidths may cause erythrocyte vaporization, rapid thermal expansion, and mechanical vessel rupture with hemorrhage. Long pulsewidths appear to cause thermal denaturation with less mechanical vessel damage. The selective, nonhemorrhagic, vascular necrosis caused by the long-pulsewidth dye laser may lead to a more desirable clinical outcome in the therapy of blood vessel disease processes.     

Flashlamp-pumped pulsed dye laser for port-wine stains in infancy: earlier versus later treatment

Twelve children, 6 to 30 weeks of age (average 14.9 weeks), with port-wine stains of the head and neck were treated with the flashlamp-pumped pulsed dye laser at 585 nm and 450 microsecond pulse duration. Ten of 12 patients (83%) showed more than 50% lightening of their port-wine stains after 2.9 treatment sessions (2.9 +/- 1.4 [+/- standard deviation]). Forty-five percent of the patients demonstrated 75% or more lightening of their lesions after a mean of 3.8 treatments (+/- 1.6). No lesions in this group cleared completely after a mean of 2.8 treatments. Treated skin was identical in texture to normal skin in all patients. There was no evidence of depressed scars, atrophy, hyperpigmentation, or hypopigmentation in the treated areas. These results indicate that pulsed dye laser treatment of port-wine stains can be undertaken safely in infancy.     

Continuous wave dye laser therapy of port wine stains

A continuous wave dye laser emitting light at 577 nm has been used in the treatment of 100 patients with port wine stains. Subjective assessments in 92 patients revealed an excellent or good result in 63% and a fair result in 17%. There was a 5% incidence of hypertrophic scarring and a 5% incidence of post-inflammatory hyperpigmentation. Overall, 12% of patients experienced a poor result. The best results were obtained in older patients with purple port wine stains.     

Numbers of murine dermal mast cells remain unchanged during chronic ultraviolet B irradiation

Dermal mast cell numbers reportedly increase in response to chronic ultraviolet irradiation in both humans and in the HRS/Skh-1 mouse model of human photoaging. It has been hypothesized that these increased numbers of mast cells are responsible, at least in part, for the damage in this chronically irradiated or photoaged skin. However, few actual quantitative data have been reported to support this claim of increased dermal mast cell numbers caused by chronic ultraviolet irradiation. We sought to quantify the numbers of dermal mast cells in the skin of chronic ultraviolet-irradiated and control HRS/Skh-1 hairless mice. Dermal mast cells from irradiated and age-matched control mice were quantified by digital image analysis during a 20-week period of exposure to ultraviolet B (UVB) radiation. During the entire course of irradiation, there was no difference in the numbers of dermal mast cells between the irradiated and nonirradiated age-matched control mice. Visible physical evidence of the effects of chronic UVB irradiation, i.e., skin wrinkling, was evident after 6 weeks of treatment. The numbers of dermal mast cells in unirradiated age-matched NSA (CF-1) haired mice were three- to four-fold lower than those in either ultraviolet-exposed or unexposed HRS/Skh-1 mice. These findings indicate that dermal mast cell numbers in HRS/Skh-1 mice are not increased by chronic exposure to UVB radiation.     

Effect of ultraviolet irradiation on mast cell-deficient W/Wv mice

The effect of UV irradiation on the skin was investigated in (WB-W/+) X (C57BL/6J-Wv/+)F1-W/Wv mice, which are genetically deficient in tissue mast cells. Their congenic littermates (+/+) and normal albino mice (ICR or BALB/c) were used as controls. Mice were irradiated with 500 mJ/cm2 of UVB and the increment of ear thickness was measured before and 6, 12, and 24 h after irradiation. Ear swelling in W/Wv mice at 12 and 24 h after irradiation was significantly smaller than that in +/+ and ICR mice. In contrast, the number of sunburn cells formed 24 h after UVB irradiation (200 or 500 mJ/cm2) was similar in W/Wv, +/+ and ICR mice. On the other hand, when mice were treated with 8-methoxy-psoralen (0.5%) plus UVA irradiation (4 J/cm2) (topical PUVA), ears of W/Wv and BALB/c mice, which were both white in color, were thickened similarly 72 h after treatment, but less swelling was observed in +/+ mice, which were black in skin color. The amount of prostaglandin D2 (PGD2) in ears, determined by radioimmunoassay specific for PGD2, was elevated 3-fold in +/+ and ICR mice at 3 h after irradiation with 500 mJ/cm2 of UVB in comparison with basal level without irradiation. However, such elevation was not observed in W/Wv mice. These results suggest that mast cells play an important role in UVB-induced inflammation, and PGs from mast cells are responsible at least in part for the development of this reaction. However, neither mast cells nor PGs contribute to the sunburn cell formation and ear swelling response by PUVA treatment.     

Laser treatment of rosacea: a pathoetiological study

OBJECTIVE: To study the effect of laser treatment on rosacea, a common facial skin disease with symptoms of blushing, redness, telangiectasis, papules, pustules, and diffuse swelling of the skin, we focused on the stinging sensation and performed immunohistochemical evaluation of nerve density and neuropeptide expression. DESIGN: Clinical investigation as well as the lactic acid (stinger) test was performed before and 3 months after the treatment with flashlamp pulsed dye laser, when skin biopsy specimens were also taken. SETTING: University hospital. PATIENTS: Thirty-two patients with rosacea, all with positive results from the lactic acid "stinger" test, were treated by flashlamp pulsed dye laser. MAIN OUTCOME MEASURES: The biopsy specimens were taken from the stinger-positive areas in the nasolabial folds, fixed in Lanas fixative (10% formalin and 0.4% picric acid), and analyzed for the expression of protein gene product 9.5 (general nerve marker), substance P, calcitonin gene-related peptide, and vasoactive intestinal polypeptide, using a biotinylated streptavidin technique. RESULTS: Thirty-one patients who were stinger positive before treatment showed decreased scores after treatment, and 1 patient had the same stinger test score before and after treatment. The number of protein gene product 9.5-positive fibers in the epidermis (P< .05) as well as the papillary dermis (P< .01) was decreased. This was also the case for substance P in the papillary dermis (P< .001), whereas no evident difference was noted for vasoactive intestinal polypeptide and calcitonin gene-related peptide. No difference was found for contact between nerves and vessels (factor VIII positive). CONCLUSIONS: Laser treatment of rosacea that destroys small vessels has a good medical relevance because it reduces the unpleasant symptoms of the sensitive skin. A neurogenic etiology of stinging may be possible.     

Utility of Dermoscopy before and after Laser Irradiation in Port Wine Stains

Background

Port wine stains (PWSs) are commonly treated with pulsed dye laser (PDL) as a standard therapy. However, it is not easy to predict the minimal effective dose in the first treatment session.

Objective

The aim of this study was to assess whether dermoscopic findings before and after laser irradiation corresponded with the clinical improvement of PWS in patients undergoing PDL therapy.

Methods

Seven untreated PWSs in 6 patients (a male and 5 females), who presented to our hospital between May 2008 to January 2010, were assessed in this study. The mean age was 36.3 years, ranging from 14 to 57 years. A PDL with a wavelength of 585 nm and a spot size of 7 mm was used. Before and after test irradiation, patients underwent dermoscopy and clinical photography, and we assessed whether the dermoscopic findings corresponded with clinical improvement after 3 months.

Results

There were no obvious differences observed in the clinical photographs between each test level immediately after irradiation. However, dermoscopic photographs showed differences as the irradiated energy increased. These changes corresponded to the clinical improvement after 3 months.

Conclusion

Our study indicates that the minimal effective fluence can be predicted by observing dermoscopic change immediately after irradiation. We think that examining the dermoscopic findings immediately after irradiation allows the laser surgeon to predict the minimal effective fluence and this prevents adverse effects of the skin.     

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.     

Vascular lasers and IPLS: Guidelines for care from the European Society for Laser Dermatology (ESLD)

Dermatology and dermatologic surgery have rapidly evolved during the last two decades thanks to the numerous technological and scientific acquisitions focused on improved precision in the diagnosis and treatment of skin alterations. Given the proliferation of new devices for the treatment of vascular lesions, we have considerably changed our treatment approach. Lasers and non‐coherent intense pulse light sources (IPLS) are based on the principle of selective photothermolysis and can be used for the treatment of many vascular skin lesions. A variety of lasers has recently been developed for the treatment of congenital and acquired vascular lesions which incorporate these concepts into their design. The list is a long one and includes pulsed dye (FPDL, APDL) lasers (577?nm, 585?nm and 595?nm), KTP lasers (532?nm), long pulsed alexandrite lasers (755?nm), pulsed diode lasers (in the range of 800 to 900?nm), long pulsed 1064 Nd:YAG lasers and intense pulsed light sources (IPLS, also called flash‐lights or pulsed light sources). Several vascular lasers (such as argon, tunable dye, copper vapour, krypton lasers) which were used in the past are no longer useful as they pose a higher risk of complications such as dyschromia (hypopigmentation or hyperpigmentation) and scarring. By properly selecting the wavelength which is maximally absorbed by the target – also called the chromophore (haemoglobin in the red blood cells within the vessels) – and a corresponding pulse duration which is shorter than the thermal relaxation time of that target, the target can be preferentially injured without transferring significant amounts of energy to surrounding tissues (epidermis and surrounding dermal tissue). Larger structures require more time for sufficient heat absorption. Therefore, a longer laser‐pulse duration has to be used. In addition, more deeply situated vessels require the use of longer laser wavelengths (in the infrared range) which can penetrate deeper into the skin. Although laser and light sources are very popular due to their non‐invading nature, caution should be considered by practitioners and patients to avoid permanent side effects. These guidelines focus on patient selection and treatment protocol in order to provide safe and effective treatment. Physicians should always make the indication for the treatment and are responsible for setting the machine for each individual patient and each individual treatment. The type of laser or IPLS and their specific parameters must be adapted to the indication (such as the vessel's characteristics, e.g. diameter, colour and depth, the Fitzpatrick skin type). Treatments should start on a test patch and a treatment grid can improve accuracy. Cooling as well as a reduction of the fluence will prevent adverse effects such as pigment alteration and scar formation. A different number of repeated treatments should be done to achieve complete results of different vascular conditions. Sunscreen use before and after treatment will produce and maintain untanned skin. Individuals with dark skin, and especially tanned patients, are at higher risk for pigmentary changes and scars after the laser or IPLS treatment.