William A. Farinelli

Damage to hair follicles by normal-mode ruby laser pulses

BACKGROUND Although many temporary treatments exist for hirsutism and hypertrichosis, a practical and permanent hair removal treatment is needed. OBJECTIVE Our purpose was to study the use of normal-mode ruby laser pulses (694 nm, 270 microseconds, 6 mm beam diameter) for hair follicle destruction by selective photothermolysis. METHODS Histologically assessed damage in ex vivo black-haired dog skin after the use of different laser fluences was used to design a human study; 13 volunteers with brown or black hair were exposed to normal-mode ruby laser pulses at fluences of 30 to 60 J/cm2, delivered to both shaved and wax-epilated skin sites. An optical delivery device designed to maximize light delivery to the reticular dermis was used. Hair regrowth was assessed at 1, 3, and 6 months after exposure by counting terminal hairs. RESULTS Fluence-dependent selective thermal injury to follicles was observed histologically. There was a significant delay in hair growth in all subjects at all laser-treated sites compared with the unexposed shaven and epilated control sites. At 6 months, there was significant hair loss only in the areas shaved before treatment at the highest fluence. At 6 months, four subjects had less than 50% regrowth, two of whom showed no change between 3 and 6 months. Transient pigmentary changes were observed; there was no scarring. CONCLUSION Selective photothermolysis of hair follicles with the normal-mode ruby laser produces a growth delay consistent with induction of prolonged telogen with apparently permanent hair removal in some cases.

Fractional CO2 laser‐assisted drug delivery

Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO2 laser AFR using methyl 5‐aminolevulinate (MAL), a porphyrin precursor, as a test drug.

Selective cryolysis: a novel method of non-invasive fat removal.

Excess fat poses a host of local and systemic problems. Various energy sources, for example, laser, ultrasound, and radiofrequency electric current have been studied as potential non‐invasive treatments aimed at local destruction of subcutaneous fat. Cryosurgery at very low temperatures is routinely used for non‐specific tissue destruction, however the potential for tissue‐specific cold injury has not been investigated. This study describes non‐invasive cold‐induced selective destruction of subcutaneous fat.

Enhanced uptake and photoactivation of topical methyl aminolevulinate after fractional CO2 laser pretreatment.

Photodynamic therapy (PDT) of thick skin lesions is limited by topical drug uptake. Ablative fractional resurfacing (AFR) creates vertical channels that may facilitate topical PDT drug penetration and improve PDT‐response in deep skin layers. The purpose of this study was to evaluate whether pre‐treating the skin with AFR before topically applied methyl aminolevulinate (MAL) could enable a deep PDT‐response.

585-NM Pulsed Dye Laser Treatment of Glottal Dysplasia

Management of glottal dysplasia can be difficult and often results in a suboptimal treatment outcome. The surgeon and patient must cooperatively balance decisions regarding the effects of possible malignancy, vocal dysfunction, and recurrences leading to multiple use of general anesthetics. A pilot study was done in 57 cases (36 patients and 97 vocal folds) without complication to evaluate the effectiveness of a 585-nm pulsed dye laser (PDL; 450-μs pulse width, 19 to 76-J/cm2 fluence, 1- to 2-mm spot size) in the treatment of vocal fold keratosis. Forty of the 57 cases had bilateral treatment. Phonomicrosurgical resection was done in 35 of the 57 cases after PDL treatment. Of this group, 10 cases were found to have hyperplasia, 21 dysplasia, 4 carcinoma in situ, and 1 carcinoma. One patient had phonomicrosurgical resection before PDL treatment. In 21 of the 57 cases, the disease was irradiated without resection (4 unilateral lesions and 17 bilateral lesions). Approximately 80% of the patients in this series had a greater than 70% reduction in the size of the lesion with the use of the PDL irrespective of whether they underwent resection. Clinical observation revealed no new anterior commissure web formation despite bilateral anterior commissure treatment in 28 of the 57 cases. The PDL enhanced the epithelial excision by improving hemostasis and by creating an optimal dissection plane between the basement membrane and the underlying superficial lamina propria. In this initial trial, the PDL provided relatively safe and effective treatment for glottal dysplasia. Analysis of patterns of recurrence will require longer follow-up.

Pulsed photothermal radiometry in turbid media: internal reflection of backscattered radiation strongly influences optical dosimetry

The integrated irradiance (energy fluence rate) within tissue can exceed the incident irradiance due to backscattered and multiply reflected light near the sample surface. This was studied quantitatively using pulsed photothermal radiometry, which measures blackbody radiation emitted by a sample during and after absorption of an optical pulse. Aqueous gels containing absorbing dye with or without various scattering materials were studied using a fast sensitive IR detector system and 1-micros tunable pulsed dye laser. For nonscattering samples, the temperature transient (T-jump) due to absorption of a laser pulse was consistent with Beers law for homogeneous absorbing media. When scattering was present, increases of up to almost an order of magnitude in the T-jump were observed. For a given absorption coefficient, there was a proportional relationship between the increase in the T-jump and the samples diffuse reflectance. A model describing the reflectance of diffuse radiation at the sample boundary was derived to explain this result. To test the model, the refractive index was varied with air as the external medium and was also matched to that of BaF(2) as the externalmedium. The subsurface fluence is, to areasonable approximation, given by E congruent with E(0)(l + 2bR),where E(0) is the incident fluence of an infinitely wide collimated beam, b is a coefficient strongly dependent on only the refractive index, and R is the measured diffuse reflectance of the sample. This study shows that irradiance within tissues can greatly exceed the irradiance of incident collimated light, an effect that should be accounted for in photomedical dosimetry or research.

Ruby laser hair removal : Evaluation of long-term efficacy and side effects

Although several studies on laser‐assisted hair removal have been published, data on long‐term follow‐up are few. The present study investigated the long‐term efficacy and safety of normal‐mode ruby laser pulses on hair removal.

Fractional laser-assisted delivery of methyl aminolevulinate: Impact of laser channel depth and incubation time†

Pretreatment of skin with ablative fractional lasers (AFXL) enhances the uptake of topical photosensitizers used in photodynamic therapy (PDT). Distribution of photosensitizer into skin layers may depend on depth of laser channels and incubation time. This study evaluates whether depth of intradermal laser channels and incubation time may affect AFXL‐assisted delivery of methyl aminolevulinate (MAL).

Safety and effectiveness of black tattoo clearance in a pig model after a single treatment with a novel 758 nm 500 picosecond laser: a pilot study.

Optimal selective photothermolysis of a pigment particle requires pulse durations equal to or less than the particles thermal relaxation time (t½). Since tattoo particles in skin range in diameter from 40 to 300 nm, picosecond pulses would approximate t½ more closely and, therefore, might be more effective at tattoo particle fragmentation.

The impact of treatment density and molecular weight for fractional laser-assisted drug delivery.

Ablative fractional lasers (AFXL) facilitate uptake of topically applied drugs by creating narrow open micro-channels into the skin, but there is limited information on optimal laser settings for delivery of specific molecules. The objective of this study was to investigate the impact of laser treatment density (% of skin occupied by channels) and molecular weight (MW) for fractional CO(2) laser-assisted drug delivery. AFXL substantially increased intra- and transcutaneous delivery of polyethylene glycols (PEGs) in a MW range from 240 to 4300 Da (Nuclear Magnetic Resonance, p<0.01). Increasing laser density from 1 to 20% resulted in augmented intra- and transdermal delivery (p<0.01), but densities higher than 1% resulted in reduced delivery per channel. Mass spectrometry indicated that larger molecules have greater intracutaneous retention than transcutaneous penetration. At 5% density, median delivery of PEGs with mean MW of 400, 1000, 2050 and 3350 Da were respectively 0.87, 0.31, 0.23 and 0.15 mg intracutaneously and 0.72, 0.20. 0.08 and 0.03 mg transcutaneously, giving a 5.8- and 24.0-fold higher intra- and transcutaneous delivery of PEG400 than PEG3350 (p<0.01). This study substantiates that fractional CO(2) laser treatment allows uptake of small and large molecules into and through human skin, and that laser density can be varied to optimize intracutaneous or transcutaneous delivery.