Short pulse intense pulsed light versus pulsed dye laser for the treatment of facial redness.

Treating diffuse facial redness with an intense pulsed light (IPL) source usually requires multiple sessions and may not achieve complete clearance. The 595 nm pulsed dye laser (PDL) enjoys a good reputation for reducing facial redness with non-purpuric settings. The objective of this study was to compare facial redness reduction using these two devices. After establishing the lowest light dose able to achieve transient purpura for the same pulse width of 1,5 ms with each technology, right and left sides of the face were randomly assigned for each type of treatment. There were two treatment sessions 4 weeks apart and the final evaluation was performed 8 weeks after thesecond treatment. Four blinded experienced dermatologists analyzed pre and post-treatment photographs, which demonstrated an average of 60% improvement on the segment treated with the IPL as opposed to 45% on the other segment. Pain level was described as mild and the procedure was well tolerated for both types of treatment. In this study we showed that short-pulsed intense pulsed light and PDL are similar in decreasing facial redness when non-purpuric low fluence settings are used. The IPL was faster and did not have consumables.

Optimal pulse durations for the treatment of leg telangiectasias with an alexandrite laser.

BACKGROUND AND OBJECTIVES: Determine optimal settings using a long pulse 755 nm alexandrite laser in the treatment of superficial leg veins. STUDY DESIGN\ MATERIALS AND METHODS: Fifteen patients with Fitzpatrick skin types I-III with telangiectasia ranging from 0.2 to 1.0 mm were enrolled. Spot size varied from 3 to 6 mm. Pulse durations ranged from 3 to 100 milliseconds. For each pulse duration, test sites were performed to determine threshold radiant exposures using persistent bluing and/or immediate stenosis (closure) as the clinical endpoint. Test sites were re-evaluated 21 days later. Optimal settings, those that resulted in the greatest clearance with minimal side effects (pain, purpura, epidermal damage, pigment changes), were used to treat a larger area of like-sized vessels. Follow-up evaluations were conducted 12 weeks after a single treatment using the optimal setting. Polarized digital photographs were obtained at each visit. Improvement was determined by blinded evaluation of pre/post-treatment photographs. RESULTS: Fourteen patients completed the study. Radiant exposure thresholds for immediate vessel changes depended on vessel diameter, with larger radiant exposures required for smaller spot sizes and smaller vessels. The average threshold radiant exposure for closure was 89 J/cm(2). The optimal pulse duration was 60 milliseconds for most of the patients. With this pulse width, clearance approached 65% 12 weeks after a single treatment. Transient hyperpigmentation occurred in four patients. Increasing the pulse duration improved epidermal tolerance and decreased the likelihood of purpura. CONCLUSIONS: By lengthening the pulsewidth beyond 3 milliseconds, a long pulse alexandrite laser achieves satisfactory clearance with an improved side effect profile.

One-pass CO2 versus multiple-pass Er:YAG laser resurfacing in the treatment of rhytides: a comparison side-by-side study of pulsed CO2 and Er:YAG lasers.

BACKGROUND: The CO2 laser is normally described as an aggressive resurfacing tool, whereas the erbium:YAG laser has enjoyed a reputation as the ideal tool for superficial resurfacing. The implication from many studies is that the CO2 laser is incapable of "minimally invasive" resurfacing. OBJECTIVE: To compare a short-pulsed CO2 laser with an Er:YAG laser over a range of parameters intended to produce equivalent microscopic and clinical injuries. METHODS: A prospective, randomized, comparative interventional trial was conducted in a tertiary care teaching hospital. Thirteen patients with facial wrinkles were enrolled in the study. A side-by-side comparison was performed using periorbital and perioral regions as treatment sites. One side was treated with a pulsed CO2 laser and the other with an Er:YAG laser. Postauricular skin was treated in an identical fashion to the study sites and biopsied for microscopic analysis. The biopsies were obtained before treatment, immediately after treatment, and either 3 or 6 months after treatment to evaluate the acute level of injury and subsequent degree of fibroplasia. Photographs were taken at baseline, immediately after treatment, 1, 2, and 6 weeks, and 3 and 6 months after treatment. Nine physicians evaluated the photographs for erythema, pigmentation, and wrinkle improvement. RESULTS: Investigator assessment showed no statistically significant differences between the lasers with respect to hyperpigmentation and wrinkle reduction. There was less erythema at the CO2 laser-treated sites 2 weeks after treatment; the differences had resolved by 6 weeks after treatment. Histologic examination demonstrated equivalent dermal thermal injury on immediate postoperative biopsies and equivalent fibroplasia on subsequent biopsies. Both CO2 and Er:YAG laser-treated sites showed overall modest wrinkle improvement compared to the pretreatment photographs. CONCLUSION: When CO2 and Er:YAG lasers are used in a manner such that there are equivalent immediate postoperative histologic results, equivalent healing and cosmetic improvement occurs. One can use CO2 laser with one pass to mimic a moderately aggressive Er:YAG laser treatment.

Hair reduction using a scanning 800 nm diode laser.

BACKGROUND: Numerous lasers are currently available for hair removal, yet there are still few studies that have examined the role of fluence, light dose, hair color, and treatment number in laser hair reduction. OBJECTIVE: To demonstrate the efficacy and safety of a scanning 800 nm diode laser for hair reduction. METHODS: An 800 nm scanning diode laser was used to deliver 24, 38, or 48 J/cm2 to a 3 cm x 3 cm area of skin located on the back, groin/bikini area, or thigh in 36 adult patients with varying shades of brown or black hair. Patients received one to four treatments during the course of the study. Hair loss was evaluated at both 30 and 90 days after final treatment. Biopsies were obtained from 20 consenting patients. RESULTS: Significant fluence-dependent hair reduction was demonstrated between treatment and control groups. At 48 J/cm2, the highest dose, a mean hair reduction of 43% was achieved 30 days after the final treatment, and 34% was achieved 90 days after the final treatment. Darker hairs were more effectively treated than lighter hairs. CONCLUSIONS: Hair reduction can be safely and effectively achieved using a scanning 800 nm diode laser.

Tattoo darkening and nonresponse after laser treatment: a possible role for titanium dioxide.

OBJECTIVE: To examine relationships between chemical composition, biopsy findings, and clinical outcome in laser-treated tattoos. DESIGN: Observational nonblinded retrospective study. SETTINGS: University-based dermatology clinic and private practice. PARTICIPANTS: Twenty patients who underwent biopsy of laser-treated tattoos. MAIN OUTCOME MEASURES: Biopsy specimens were analyzed after laser treatment, and the depths of changed particles were recorded. Ultrastructure of the changed particles was examined by electron microscopy. Presence of inorganic chemicals was determined by x-ray diffraction. Correlation between x-ray diffraction, microscopy, and clinical response was attempted. RESULTS: Of the 20 tattoos, 7 lightened, 9 failed to change, and 4 darkened after laser treatment. There was a significant association between presence of titanium dioxide and poor response to laser therapy. Microscopic studies showed variable changes in the ink particles, but there was a trend toward residual deep green pigment in the resistant tattoos. Also, round dark stippling was observed superficially in the darkened specimens. CONCLUSIONS: Titanium is overrepresented in tattoos that respond poorly to laser treatment. Further studies are necessary to show whether this metal is the primary cause of this poor response.

Nonablative skin remodeling: selective dermal heating with a mid-infrared laser and contact cooling combination.

BACKGROUND AND OBJECTIVE: Many of the microscopic changes associated with photodamage reside in the dermis. It follows that subsurface heating of the skin might allow for cosmetic enhancement without loss of the epidermis. Accordingly, we investigated the clinical and microscopic changes produced by a mid-infrared laser coupled with a contact cooling device. STUDY DESIGN/MATERIALS AND METHODS: Nine patients were treated with an erbium glass laser and sapphire cooling handpiece in contact with the skin. Postauricular sites were irradiated with pulse energies varying from 400-1,200 mJ and numbers of pulses from 4 to 40. Outcome measures included pain, edema, and erythema at predetermined postoperative intervals. Biopsies were performed just after treatment and 2 months postoperatively for selected pulse energy-pulse number combinations. RESULTS: Erythema, edema, and pain increased with pulse energy and number of pulses. Likewise, immediate epidermal necrosis and subsequent scarring were observed for larger pulse energy-pulse number combinations. At sites with epidermal preservation, on biopsy, immediate dermal thermal damage was observed in a band-like pattern. The deep boundaries of this band were dependent on pulse energy and pulse number. After 8 weeks, biopsies showed dermal fibroplasia roughly correlating to the band of immediate dermal thermal damage. CONCLUSION: Selective dermal heating can be achieved with a mid-infrared laser coupled to a contact surface cooling device. In this study, the range of fibroplasia and lack of clinically substantial cosmetic enhancement suggest that the dermal thermal damage achieved may be too deep and that the injury should be confined to more superficial levels to alter the most severely photodamaged dermis. Lasers Surg. Med. 26:186-195, 2000. Published 2000 Wiley-Liss, Inc.

Comparison of carbon dioxide laser, erbium:YAG laser, dermabrasion, and dermatome: a study of thermal damage, wound contraction, and wound healing in a live pig model: implications for skin resurfacing.

BACKGROUND: Advances in laser technology allow for precise tissue removal and minimal thermal damage. However, mechanisms for cosmetic improvement have not been determined. Investigators have suggested that ablation, collagen shrinkage, and new collagen deposition all contribute to the clinical outcome. OBJECTIVE: In a live farm pig, we examined gross and microscopic effects of thermal and mechanical ablation devices to characterize immediate and long-term mechanisms in skin rejuvenation. METHODS: Two CO(2) lasers, an erbium:YAG laser, a dermabrader, and a dermatome were used to treat flank skin in a farm pig. There were 14 different treatment groups based on device type and working parameters. One to five sites were treated for each group. Wound surface areas were measured before treatment, immediately after treatment, and 7, 17, 23, 30, and 60 days thereafter. Biopsies were performed immediately after irradiation and 2, 7, 17, and 60 days after treatment. RESULTS: For the CO(2) laser-induced wounds, surface area measurements showed that immediate and final wound contraction tended to increase with initial residual thermal damage (RTD) for a range of values, above which immediate contraction remained relatively constant. Although there was no immediate wound contraction with mechanical ablation devices, long-term wound contraction in the dermatome and dermabrasion sites increased with depth of ablation. The erbium:YAG laser sites healed in a manner similar to that of mechanically induced wounds. Wound contraction profiles over time were dependent on depth of RTD and depth of ablation. Sixty days postoperatively, histologic examination showed varying degrees of fibroplasia. Overall, there was greater compaction and horizontal orientation of collagen fibers in those wounds with more than 70 microm of dermal RTD. Grossly, all wounds were similar after 60 days, with the exception of the deep dermabrasion sites, at which clinical scarring was observed. CONCLUSION: Our results show that CO(2) laser resurfacing produces short- and long-term wound contraction that is greater than that induced by purely ablative methods for the same total depth of injury. The erbium laser produced wound contraction profiles similar to those produced by mechanical wounding. The data suggest that initial collagen contraction and thermal damage modulate wound healing.

A pilot study of in vivo immediate tissue contraction with CO2 skin laser resurfacing in a live farm pig.

BACKGROUND: It has been suggested that tissue ablation, collagen shrinkage, and new collagen deposition contribute to the clinical outcome of laser skin resurfacing. OBJECTIVE: To study the effects of fluence and pass number on thermal damage and tissue shrinkage, we performed experiments in an in vivo farm pig model. METHODS: A CO2 laser was used to treat the flank skin of a farm pig. There were nine treatment sites based on number of passes and fluence per pass. Wound surface areas were measured pretreatment and immediately posttreatment. Biopsies were performed immediately after irradiation. RESULTS: Surface area measurements showed that immediate contraction tended to increase with increasing fluence and pass number up to a maximum of approximately 38% shrinkage, after which the percent contraction remained constant. Thermal damage increased with pass number for low and moderate fluence groups; however, in high fluence groups the thermal damage remained constant with an increasing number of passes. CONCLUSIONS: Our results suggest that CO2 laser resurfacing produces immediate tissue contraction and residual thermal damage that is saturable for multiple passes and high fluences. For small fluences, however, there is an almost linear increase in thermal damage and shrinkage with an increasing number of passes.

Theoretical considerations in laser hair removal.

A systematic and logical approach for laser hair removal demands an understanding of its biologic and physical bases. This article presents an overview of hair anatomy and physiology followed by a mathematically nonrigorous review of tissue optics and thermal responses to laser irradiation. The reader is provided with a step by step approach to laser hair removal.

Effects of overlap and pass number in CO2 laser skin resurfacing: a study of residual thermal damage, cell death, and wound healing.

BACKGROUND: Newer CO2 laser systems incorporating short pulse and scanning technology have been used effectively to resurface the skin. As the number of resurfacing cases has increased, hypertrophic scarring has been reported more commonly. Previous dermabrasion and continuous wave CO2 studies have suggested that depth of injury and thermal damage are important predictors of scarring for a given anatomic region. To determine whether rapid overlapping of laser pulses/scans significantly altered wound healing, we examined residual thermal damage, cell death, and histologic and clinical wound healing in a farm pig. METHODS AND MATERIALS: Two popular CO2 systems were used, with a range of radiant exposures, degrees of overlap, and numbers of passes. Thermal damage was assessed by histology, and dermal cell viability was measured with nitrotetrazolium blue staining. Presence or absence of clinical scarring was determined by textural change and loss of skin markings. RESULTS: We observed that dermal thermal damage did not increase significantly with pass number when performed as in the normal clinical setting (for 2-4 passes); however, by delivering rapidly overlapping pulses and scans, residual thermal damage and cell death depth were increased as much as 100% over areas without immediate overlap of laser impacts. CONCLUSIONS: Immediate overlapping of CO2 laser pulses and scans is a significant risk factor in increasing thermal damage, cell death, and possibly scarring.

Why does carbon dioxide resurfacing work? A review.

Despite the unquestionable efficacy of carbon dioxide laser skin resurfacing, mechanisms for cosmetic enhancement remain poorly characterized. Histological studies have provided some insight into the cascade of events from initial laser impact to final skin rejuvenation. However, there are few comprehensive studies of gross and microscopic wound healing. Additionally, the literature is fragmented; excellent individual articles appear in journals from widely disparate disciplines. For example, some reports relevant to laser skin resurfacing are "sequestered" in the engineering literature. This article is intended to update the physician on laser skin resurfacing based on the broadest review of the current literature. It proceeds from a discussion of initial laser-tissue interactions, such as collagen denaturation, to examination of long-term biological sequelae. At some cost to scientific rigor, mathematical models describing laser-tissue interactions are not presented.

The use of the 1.0 mm handpiece in high energy, pulsed CO2 laser destruction of facial adnexal tumors.

BACKGROUND: The treatment of syringoma and trichoepithelioma has included punch and shave biopsy, excision, electrodessication, as well as continuous wave and superpulsed carbon dioxide laser ablation. More recently, high-energy pulsed CO2 lasers have been reported to be effective with standard available handpieces that deliver collimated beams. OBJECTIVE: To report our experience using a focusing handpiece (1.0 mm spot at focus) with a high energy pulsed CO2 laser. METHODS: Four patients with syringoma and two with multiple trichoepithelioma were treated with a high energy pulsed CO2 laser using a 1 mm spot size focusing handpiece. Pulse energies ranged from 125 to 250 mJ. All patients were followed 2 weeks after treatment and then for variable periods ranging from 8 to 18 months (mean=13.3 months). RESULTS: The 1 mm spot focusing handpiece permitted rapid tumor ablation with optimal matching of lesion size and laser spot diameter. Recurrence of tumor was associated with superficial ablation while complications such as hypopigmentation and atrophy were associated with deeper ablation. CONCLUSION: Facial adnexal tumors such as syringoma and trichoepithelioma can be successfully treated with the 1.0 mm handpiece in tandem with high energy pulsed CO2 lasers.

Lasers in the military for cutaneous disease and wound healing.

The clinical laser experience of military dermatologists mirrors that of their civilian counterparts; however, there are applications for lasers in dermatology in which there is special military relevance. These range from treatment of common diseases such as pseudofolliculitis barbae to noninvasive identification of shrapnel injuries on the battlefield using novel laser-based diagnostic techniques. Although some applications in this report are experimental, emerging technologies should allow for their clinical or field implementation in the near future.

The effect of wiping on skin resurfacing in a pig model using a high energy pulsed CO2 laser system.

BACKGROUND: The impact of wiping in laser skin resurfacing has not been systematically studied. METHODS: We examined the effects of wiping during single- and multiple-pass high energy pulsed CO2 laser skin resurfacing in a farm pig. Consequences of wiping were evaluated with regard to depth of residual thermal damage, tissue necrosis, and fibroplasia. Also, the impact of wiping on gross wound healing was observed. Wounds were followed for 21 days and biopsies were obtained on postoperative days 0, 1, and 21. RESULTS: Immediate postoperative biopsies of single-pass wounds showed equivalent residual thermal damage regardless of wiping; in contrast, biopsies from multiple-pass sites without wiping showed more extensive and variable residual thermal damage than wiped sites. On postoperative day one, single pass sites without wiping were grossly less erythematous than wiped sites, and biopsies showed less extensive necrosis and inflammation. In contrast, multiple pass sites without wiping were grossly more erythematous than corresponding wiped sites, and biopsies revealed significantly increased and variable necrosis. After 21 days, multiple pass sites without wiping were grossly more erythematous and showed a thicker band of fibroplasia microscopy. CONCLUSIONS: For single pass wounds, not wiping decreased the level of wounding. In contrast, not wiping in multiple pass wounds significantly increased the depth and variability of residual thermal damage and necrosis, resulting in prolonged healing.

The clinical superiority of continuous exposure versus short-pulsed carbon dioxide laser exposures for the treatment of pearly penile papules.

Treatment of pearly penile papules was performed both with a conventional continuous-wave (CW) and a newer generation high energy pulsed carbon dioxide laser. When compared to the short pulsed laser, the CW laser, using relatively low power densities, provided superior hemostasis and improved visualization of the operative field. Despite the increase in thermal injury, wound healing was not compromised. The results of this case report support the CO2 laser in CW mode as the infrared laser treatment of choice for exophytic lesions with increased vascularity.