Picosecond Laser treatment of Striae Distensae: In vivo Evaluation of Results by 3D Analysis, Reflectance Confocal Microscopy, and Patient's Satisfaction

Cosmetic Considerations in Dark-Skinned Patients

For dermatologists, diversities of human races result in an opportunity to encounter patients with various skin types. Cosmetic procedures have gained more popularity and become more accessible over the past decades. Thus, the selection of appropriate treatment protocol for each patient becomes inevitable. This review will focus on basic knowledge and key points in performing safe cosmetic-related procedures in patients with dark-complexioned skin. In terms of structure and function of the skin, people of color have equal epidermal thickness, corneocyte size and melanocyte number. However, they have more stratum corneum compaction, melanosome dispersion and melanocyte activity than fair skin individuals. Data regarding drug penetration and cutaneous irritation showed conflicting results. Superficial chemical peels and microdermabrasion can be done safely in dark-skinned patients. Medium-depth peel should be used with extreme caution. While deep-depth peel should be avoided at all times due to pigmentary and textural complications. Prolonged treatment interval, use of priming agents and sun protection are recommended. Injectable materials including botulinum toxin and soft tissue augmentation by hyaluronic acid filler can be done harmlessly in dark-skinned patients. Lasers and energy-based devices should be done with caution. Higher melanin dispersion and melanocyte activity acts as competitive chromophore. Pigmentary or textural changes can occur after aggressive treatment protocol. High energy setting, pulse stacking, short wavelength lasers and short treatment interval should be avoided in dark-skinned patients.

Laser Treatment Monitoring with Reflectance Confocal Microscopy

Laser treatments have become popular in Dermatology. In parallel to technologic development enabling the availability of different laser wavelengths, non-invasive skin imaging techniques, such as reflectance confocal microscopy (RCM), have been used to explore morphologic and qualitative skin characteristics. Specifically, RCM can be applied to cosmetically sensitive skin areas such as the face, without the need for skin biopsies. For these reasons, apart from its current use in skin cancer diagnosis, our systematic review reveals how RCM can be employed in the field of laser treatment monitoring, being particularly suitable for the evaluation of variations in epidermis and dermis, and pigmentary and vascular characteristics of the skin. This systematic review article aims to provide an overview on current applications of RCM laser treatment monitoring, while describing RCM features identified for different applications. Studies on human subjects treated with laser treatments, monitored with RCM, were included in the current systematic review. Five groups of treatments were identified and described: skin rejuvenation, scar tissue, pigmentary disorders, vascular disorders and other. Interestingly, RCM can assist treatments with lasers targeting all chromophores in the skin and exploiting laser induced optical breakdown. Treatment monitoring encompasses assessment at baseline and examination of changes after treatment, therefore revealing details in morphologic alterations underlying different skin conditions and mechanisms of actions of laser therapy, as well as objectify results after treatment.

Characterization of picosecond laser-induced optical breakdown using harmonic generation microscopy

BACKGROUND AND OBJECTIVES

By creating microinjuries usually confined to the epidermis, a fractional picosecond 1064-nm Nd:YAG laser that delivers an array of highly focused beamlets can be effectively used for facial rejuvenation or resurfacing. However, the mechanism of dermal remodeling underlying this nonablative treatment remains unclear.

METHODS

Five participants having skin phototype III-IV were recruited for intervention using a fractional picosecond 1064-nm Nd:YAG laser system equipped with a holographic diffractive beam-splitting optic. The laser-induced histopathological changes on human skin were examined in vivo using a harmonic generation microscopy (HGM), visualizing second harmonic generation (SHG), and third harmonic generation (THG) contrasts dichromatically. SHG refers for collagen distribution, while THG represents for epidermal components in the HGM signal.

RESULTS

Histological hematoxylin and eosin staining and in vivo HGM imaging studies revealed the presence of epidermal vacuoles below the stratum granulosum along with keratinocyte degeneration or cytolysis. In addition to the epidermal vacuoles, HGM imaging exclusively demonstrated laser-induced shock wave propagation arranged as a THG-bright concentric pattern in the epidermis and loss of SHG signals in the papillary dermis immediately beneath the epidermal vacuoles.

CONCLUSIONS

Alongside generating epidermal vacuoles, the fractional picosecond 1064-nm Nd:YAG laser induced collagen changes. These collagen changes may lead to dermal remodeling and neocollagenesis underlying the fractional picosecond laser treatment.

New Progress in Therapeutic Modalities of Striae Distensae

Striae distensae (stretch marks/striae gravidarum) is one of the common cosmetic problems that can cause psychological distress and anxiety to patients due to its disfiguring damage, especially for women. The etiology of striae distensae is currently unknown, and risk factors include low maternal age, family history of stretch marks, excessive weight gain during pregnancy, and high neonatal weight. This article reviews the latest literature on the most commonly used, most popular, and novel treatment modalities and analyzes the hot spots and difficulties in striae distensae treatment in recent years. Topical treatment modalities are mainly used as an adjunctive treatment. Ablative lasers and non-ablative lasers are the most popular, among which picosecond has been tried in striae distensae treatment in the last two years. Combined treatment modalities are currently a hot spot for SD treatment, and microneedle radiofrequency and fractional CO₂ laser combined with other treatments are the most common. Microneedle radiofrequency is the most commonly used and achieved therapeutic effect among the combined treatment modalities.

Microneedle fractional radiofrequency for atrophic acne scars: in vivo evaluation of results by 3D analysis and reflectance confocal microscopy

BACKGROUND

The efficacy of microneedle fractional radiofrequency (MFR) for the treatment of atrophic acne scars has been recently described, but accurate in vivo microscopic documentation of the processes occurring has never been reported.

AIMS

The aim of this study is to describe in vivo morphological atrophic acne scars' variations after treatment with MFR by means reflectance confocal microscopy (RCM) and three-dimensional (3D) imaging.

PATIENTS/METHODS

A total of 11 patients requiring treatment for atrophic facial acne scars were treated with four monthly sessions of MFR. 3D imaging and RCM were assessed at baseline and 1 months after last session. Clinical improvement, according to Global Assessment Improvement Scale (GAIS), and patients' satisfaction were evaluated.

RESULTS

Clinical improvement was observed in all the treated patients, although better results were obtained for boxcar scars (p= 0.043). 3D imaging revealed a significant improvement in terms of mean scars' depth (p<0.001). Otherwise, RCM highlighted collagen remodeling with restoration of a reticular structure.

CONCLUSIONS

Our study confirms the efficacy and safety of MFR in acne scars' treatment and provides the microscopic description of the results using RCM. This article is protected by copyright. All rights reserved.

Treatment of abdominal striae distensae in Fitzpatrick skin types IV to V using a 1064-nm picosecond laser with a fractionated microlens array

BACKGROUND

Striae distensae are atrophic dermal scars that can cause psychosocial distress among affected patients. Despite numerous available therapeutic modalities, no gold standard treatment has been established.

OBJECTIVE

To evaluate the long-term efficacy and safety of a fractional 1064-nm picosecond laser for the treatment of striae alba in individuals with dark skin types.

MATERIALS AND METHODS

Twenty volunteers with Fitzpatrick skin types IV-V who presented with striae alba were enrolled. Subjects were treated with a fractional 1064-nm picosecond laser for four sessions at 4-week intervals. The skin texture, average melanin index (MI), and melanin variation score were assessed using Antera 3D® before treatment, at 1 month after the second treatment, and at 1, 3, and 6 months after the last treatment. Two independent investigators evaluated clinical improvement by comparing pretreatment and posttreatment photographs. The patient satisfaction rates were likewise assessed. Adverse effects were recorded during the entire study period.

RESULTS

Significant improvement of skin texture was seen at 1 month after the final treatment (p < 0.001) and continuously improved until the 6-month follow-up visit (p = 0.003). The average MI significantly increased at 1 month after the final treatment (p < 0.001), whereas the melanin variation score decreased throughout the follow-up period. Investigator assessment at the 6-month follow-up revealed that 90% of subjects had moderate to marked improvement of striae appearance. Only two of 20 subjects (10%) developed transient postinflammatory hyperpigmentation (PIH) after laser treatment.

CONCLUSION

Fractional picosecond 1064-nm laser is effective and well-tolerated for the treatment of striae alba in dark-skinned individuals with a low incidence of PIH.

Quantitative assessment of the long-term efficacy and safety of a 1064-nm picosecond laser with fractionated microlens array in the treatment of enlarged pores in Asians: A case-control study

Background

Enlarged facial pores are one of the common skin signs of photoaging that patients seek treatment for. However, objective data and long‐term assessment on the efficacy and safety of therapeutic procedures for this condition are limited.

Objective

To objectively evaluate the efficacy and safety of a 1064‐nm picosecond laser with microlens array (MLA) for pore tightening.

Methods

Twenty‐five patients with enlarged pores received three treatments with a 1064‐nm picosecond laser coupled with MLA at 4‐week intervals. Patients were evaluated using objective (measurement of pore volume using three‐dimensional photography) and subjective (clinical evaluation by two blinded dermatologists) assessments at baseline and at the 1‐, 3‐, and 6‐month follow‐ups. Adverse effects were also recorded during each visit.

Results

After three treatments, there was a significant reduction of pore size from baseline (p < 0.001). The improvement in pore size appearance significantly continued from the 1‐month to the 6‐month follow‐up visits (p = 0.013). The total average pore size was 1.15652 ± 0.614322 and 0.8087 ± 0.50515 at baseline and at 6 months after the final treatment, respectively, resulting in an average of 30% reduction in pore size. No cases of dyspigmentation, textural alteration, or scarring were documented.

Conclusion

Fractional 1064‐nm picosecond laser appears to be effective and safe for reducing pore size in Asians with minimal transient side effects.