Background and Objectives: We introduce and clinically examine a new concept of skin treatment called fractional photothermolysis (FP), achieved by applying an array of microscopic treatment zones (MTZ) of thermal injury to the skin. Study Design/Materials and Methods: Two prototype devices emitting at 1.5 mm wavelength provided a pattern of micro-exposures with variable MTZ density. Effects of different MTZ densities were tested on the forearms of 15 subjects. Clinical effects and histology were assessed up to 3 months after exposure. Treatment of photoaged skin on the periorbital area in an additional 30 subjects receiving four treatments over a period of 2–3 weeks was also tested. Tissue shrinkage and clinical effects were assessed up to 3 months after treatment. Results: Pattern densities with spacing of 250 mm or more were well tolerated. Typical MTZ had a diameter of 100 mm and penetrated 300 mm into the skin. Reepithelialization was complete within 1 day. Clinical effects were assessed over a 3-month period. Histology at 3 months revealed enhanced undulating rete ridges and increased mucin deposition within the superficial dermis. Periorbital treatments were well tolerated with minimal erythema and edema. Linear shrinkage of 2.1% was measured 3 months after the last treatment. The wrinkle score improved 18% (P < 0.001) 3 months after the last treatment. Conclusions: FP is a new concept for skin restoration treatment. Safety and efficacy were demonstrated with a prototype device. Further clinical studies are necessary to refine the optimum parameters and to explore further dermatological applications. Lasers Surg. Med. 34:426– 438, 2004. 2004 Wiley-Liss, Inc.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/lsm.20048

Fractional Photothermolysis: A New Concept for Cutaneous Remodeling Using Microscopic Patterns of Thermal Injury

Methods of applying laser light to the skin, and apparatus therefor, include methods for removing hair, for synchronizing hair growth, for stimulating hair growth, for treating Herpes virus, for reducing sweat and body odor, for in situ formation of a chromophore in hair ducts, for reducing light loss at the skin surface, for grafting of hair stem cells, and for removing keloid or hypertrophic scars. The hair removal methods include controlling the proportions of photomechanical and photothermal damage by selection of laser parameters, chromophore particle size and/or pulse duration, with optional dynamic skin cooling. Additional hair removal methods include infiltrating a photoactivated drug into hair ducts and exposing the skin to sunlight or administering an anti-proliferative agent into hair ducts, for example, by encapsulating the anti-proliferative agent in a slow release vehicle. The methods of treating Herpes virus, reducing sweat or body odor, and removing keloid or hypertrophic scars include infiltrating a light-absorbing contaminant into hair ducts or other openings in the skin and illuminating the contaminated skin section. The methods for stimulating hair growth include grafting of cloned auto hair stem cells, the hair ducts or administering methionine to a skin section to increase hair growth. Apparatus useful in performing these methods include devices for making a smooth optical boundary between skin and air or for dividing a light beam into a plurality of smaller light beams, and dressings for use before, during and after laser illumination.

Methods and devices for inhibiting hair growth and related skin treatments

Low-level laser (light) therapy (LLLT) is a fast-growing technology used to treat a multitude of conditions that require stimulation of healing, relief of pain and inflammation, and restoration of function. Although the skin is the organ that is naturally exposed to light more than any other organ, it still responds well to red and near-infrared wavelengths. The photons are absorbed by mitochondrial chromophores in skin cells. Consequently electron transport, adenosine triphosphate (ATP) nitric oxide release, blood flow, reactive oxygen species increase and diverse signaling pathways get activated. Stem cells can be activated allowing increased tissue repair and healing. In dermatology, LLLT has beneficial effects on wrinkles, acne scars, hypertrophic scars, and healing of burns. LLLT can reduce UV damage both as a treatment and as a prophylaxis. In pigmentary disorders such as vitiligo, LLLT can increase pigmentation by stimulating melanocyte proliferation and reduce depigmentation by inhibiting autoimmunity. Inflammatory diseases such as psoriasis and acne can also benefit. The non-invasive nature and almost complete absence of side-effects encourages further testing in dermatology.

Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring.

Acne has a prevalence of over 90% among adolescents and persists into adulthood in approximately 12%–14% of cases with psychological and social implications. Possible outcomes of the inflammatory acne lesions are acne scars which, although they can be treated in a number of ways, may have a negative psychological impact on social life and relationships. The main types of acne scars are atrophic and hypertrophic scars. The pathogenesis of acne scarring is still not fully understood, but several hypotheses have been proposed. There are numerous treatments: chemical peels, dermabrasion/microdermabrasion, laser treatment, punch techniques, dermal grafting, needling and combined therapies for atrophic scars: silicone gels, intralesional steroid therapy, cryotherapy, and surgery for hypertrophic and keloidal lesions. This paper summarizes acne scar pathogenesis, classification and treatment options.

/pdf/acne-scars-pathogenesis-classification-and-treatment-103xyw6k1k.pdf

Acne Scars: Pathogenesis, Classification and Treatment

The drive to attain cosmetic facial enhancement with minimal risk and rapid recovery has inspired the field of nonsurgical skin rejuvenation. Laser resurfacing was introduced in the 1980s with continuous wave carbon dioxide (CO 2 ) lasers; however, because of a high rate of side effects, including scarring, short-pulse, high-peak power, and rapidly scanned, focused-beam CO 2 lasers and normal-mode erbium-doped yttrium aluminium garnet lasers were developed, which remove skin in a precisely controlled manner. The prolonged 2-week recovery time and small but significant complication risk prompted the development of non-ablative and, more recently, fractional resurfacing in order to minimize risk and shorten recovery times. Nonablative resurfacing produces dermal thermal injury to improve rhytides and photodamage while preserving the epidermis. Fractional resurfacing thermally ablates microscopic columns of epidermal and dermal tissue in regularly spaced arrays over a fraction of the skin surface. This intermediate approach increases efficacy as compared to nonablative resurfacing, but with faster recovery as compared to ablative resurfacing. Neither nonablative nor fractional resurfacing produces results comparable to ablative laser skin resurfacing, but both have become much more popular than the latter because the risks of treatment are limited in the face of acceptable improvement. Learning objectives At the completion of this learning activity, participants should be familiar with the spectrum of lasers and light technologies available for skin resurfacing, published studies of safety and efficacy, indications, methodologies, side effects, complications, and management.

The spectrum of laser skin resurfacing: Nonablative, fractional, and ablative laser resurfacing

background.Cutaneous laser resurfacing with high-energy, pulsed and scanned carbon dioxide (CO2) lasers has become popularized for the treatment of a variety of cutaneous indications, but potential complications and side effects remain a large concern. Despite the recent boom in cutaneous laser resu

Complications of Carbon Dioxide Laser Resurfacing. An Evaluation of 500 Patients

Background: Laser-assisted hair removal has become popularized using wavelengths in both the red and infrared regions of the electromagnetic spectrum. These photoepilation devices target follicular melanin or an exogenous pigment placed within the follicle resulting in thermal damage to the hair follicle and shaft. However, melanocytes and keratinocytes located within the superficial layers of the skin also absorb red and infrared laser radiation. This may result in unwanted epidermal injury during the hair removal process. Objective: The purpose of this study was to examine a large patient population to determine the frequency of side effects using 3 different hair removal laser systems with various wavelengths, pulse durations, and treatment protocols. Methods: A retrospective chart review and digital photographic analysis of the side effects resulting from 900 consecutive laser-assisted hair removal treatments delivered over a 24-month study period, by means of either a Q-switched Nd:YAG laser with pretreatment wax-epilation and topical carbon solution, a long-pulse ruby laser with a contact cooling tip, or a long-pulse alexandrite laser are reported. Results: Treatment pain, erythema, edema, hypopigmentation and hyperpigmentation, blistering, crusting, erosions, purpura, and folliculitis were observed. The majority of undesirable tissue effects occurred on tanned skin or in Fitzpatrick skin phototypes III and higher. The ruby and alexandrite laser systems resulted in the majority of side effects seen. The effects of seasonal variations, anatomic treatment location, and sun exposure were striking within the ruby and alexandrite laser groups. No infections, scarring, or long-term complications occurred. Conclusion: Laser-assisted hair removal is a safe procedure when patient characteristics such as skin type, anatomic location, and sun-exposed or tanned skin are considered during selection of laser treatment parameters. Lasers emitting wavelengths with high melanin absorption capabilities should be used in a conservative manner when treating patients with dark skin phototypes or suntans. No long-term complications, infections, or scarring occurred in this study population. (J Am Acad Dermatol 1999;41:165-71.)

https://www.jaad.org/article/S0190-9622(99)70043-5/pdf

Laser-assisted hair removal: Side effects of Q-switched Nd:YAG, long-pulsed ruby, and alexandrite lasers

Objective: To determine the most effective treatment parameters for laser-assisted hair removal using a Q-switched neodymium:yttrium-aluminum-garnet (Nd: YAG) laser. Design: Prospective study to determine the effectiveness of Q-switched Nd:YAG laser—assisted hair removal under varying pretreatment protocols. Hair growth was assessed after laser treatment, and the results were compared with those of wax epilation at 4, 12, and 24 weeks. Setting: A private ambulatory laser facility and academic referral center. Intervention: Laser-assisted hair removal was performed under 4 different pretreatment conditions. Eighteen areas of unwanted body and facial hair from 12 study subjects were divided into 4 quadrants. Wax epilation followed by application of a carbon-based solution and exposure to Q-switched Nd:YAG laser radiation was performed on 1 quadrant. A second quadrant was wax epilated and exposed to Q-switched Nd:YAG laser radiation without prior carbon solution application. A third quadrant was exposed to laser radiation alone, and a final quadrant was wax epilated to serve as the control. Follow-up evaluations at 1, 3, and 6 months consisted of photographic documentation, manual hair counts, and patient hair-density estimates. Main Outcome Measure: Percentage of hair regrowth as assessed by objective hair counts and patient subjective evaluations. Results: Mean percentage of hair regrowth at 1 month was 39.9% for the wax-carbon-laser quadrant, 46.7% for the wax-laser quadrant, 66.1% for the laser-alone quadrant, and 77.9% for the wax control quadrant. The percentage of hair regrowth approximately doubled by 3 months but was significantly delayed in all laser-treated quadrants regardless of pretreatment protocol. Full hair regrowth in all anatomic locations was observed by month 6. Patient subjective evaluations of hair density closely approximated hair count data. No adverse effects or long-term complications were observed. Conclusions: A single hair-removal treatment with the Q-switched Nd:YAG laser is safe and effective in delaying hair growth for up to 3 months. Although the combination of pretreatment wax epilation and topical carbon solution application was effective, laser irradiation alone, with or without wax epilation, also provided a significant delay in hair growth. Arch Dermatol. 1997;133:1546-1549

Optimizing Treatment Parameters for Hair Removal Using a Topical Carbon-Based Solution and 1064-nm Q-Switched Neodymium:YAG Laser Energy

Hypertrophic burn scars are notoriously difficult to treat because of their extensive tissue involvement and tendency to worsen with hypertrophy and contracture formation. Various therapies have been advocated in the past, including surgical excision and grafting, dermabrasion, and corticosteroids, with distinct cosmetic limitations. The 585-nm pulsed dye laser has been shown previously to be effective in the treatment of a variety of traumatic and surgical scars with improvement in scar texture, color, and pliability with minimal side effects. Sixteen patients with 40 hypertrophic burn scars resulting from chemical peels, carbon dioxide laser procedures, and accidental thermal injury were treated with a 585-nm pulsed dye laser. Sequential photographic and clinical assessments were recorded in all patients. Histologic evaluations of skin punch biopsies before and after laser irradiation were performed when possible. Symptomatic improvement of scars was reported after one treatment. Decreased scar erythema with improved texture and pliability was observed after an average of 2.5 treatments. No correlation was found between scar duration, location, or etiology and response to treatment. Normal number of dermal fibroblasts with decreased sclerosis was observed on histologic examination of laser-irradiated scars. The 585-nm pulsed dye laser irradiation of hypertrophic burn scars can effectively improve scar pliability and texture and decrease erythema and associated symptoms yielding cosmetically and functionally acceptable clinical results.

Pulsed dye laser treatment of hypertrophic burn scars.

Background
Several laser systems with varying wavelengths, pulse durations, and energy fluences are currently utilized for hair removal. However, the ideal laser parameters and treatment candidates for photoepilation remain largely unknown. The medical literature lacks a wealth of experimental data to sufficiently document the long-term safety and efficacy of laser-assisted hair removal. This study examines the clinical efficacy and side effect profile of long-pulsed alexandrite laser-assisted hair removal utilizing laser pulse durations of either 5, 10, or 20 milliseconds (ms).

Study Design/Methods
Laser-assisted hair removal was performed on 36 subjects with a long-pulsed alexandrite laser. Areas of unwanted hair growth on the face, back, and legs were divided linearly into four 1 cm2 or 2 cm2 quadrants. Experimental regions included a control quadrant and three additional quadrants, which were treated with the alexandrite laser using an average fluence of 18 J/cm2, with a 10 mm spot size at either a 5, 10, or 20 ms pulse duration. Hair counts and photographs were obtained before treatment, immediately following irradiation, 1 week and 1, 3, and 6 months postoperatively.

Results
All laser-treated quadrants displayed a significant delay in hair regrowth compared to control nontreated quadrants at postoperative week 1 and months 1 and 3. Hair counts were reduced by 66% at 1 month, 27% at 3 months, and 4% at 6 months. No significant differences in clinical efficacy or side effect profiles were observed between treatment quadrants, yet a trend towards less post-treatment erythema and hyperpigmentation was noted with the 20 ms pulse duration.

Conclusions
Equivalent long-term hair removal for up to 6 months was achieved with the long-pulsed alexandrite laser at 5, 10, and 20 ms pulse durations at an average fluence of 18 J/cm2. Side effects were limited and transient. Lasers Surg. Med. 24:332–337, 1999. © 1999 Wiley-Liss, Inc.

Christopher A. Nanni

Papers

Complications of Carbon Dioxide Laser Resurfacing. An Evaluation of 500 Patients

Laser-assisted hair removal: Side effects of Q-switched Nd:YAG, long-pulsed ruby, and alexandrite lasers

Optimizing Treatment Parameters for Hair Removal Using a Topical Carbon-Based Solution and 1064-nm Q-Switched Neodymium:YAG Laser Energy

Pulsed dye laser treatment of hypertrophic burn scars.

Long-pulsed alexandrite laser-assisted hair removal at 5, 10, and 20 millisecond pulse durations.