In vivo characterization of the threshold of laser-induced optical breakdown (LIOB) of a fractional 1064 nm Nd:YAG picosecond laser by optical coherence tomography: A step forward to precision laser therapy.

BACKGROUND: Clinical endpoints serve as an important guide to physicians during laser treatment. However, there are no reliable clinical endpoints for the fractional picosecond laser-induced optical breakdown (LIOB) whose threshold is dependent on the irradiance of the laser and epidermal melanin content of the skin treated. OBJECTIVES: To determine the LIOB threshold in vivo of a 1064nm fractional picosecond laser for different skin colors. METHODS: A cellular-level resolution optical coherence tomography (OCT) has successfully demonstrated that the in vivo morphological change of LIOB in the epidermis by a fractional picosecond laser. By measuring the melanin content in the area of the skin to treat using a skin imaging device, the physician would therefore be able to determine the threshold of LIOB visually under OCT for the skin of that particular melanin content. CONCLUSION: The pilot study has demonstrated that OCT may serve as a non-invasive modality to determine the thresholds of LIOB by a fractional picosecond laser. And the established correlation between melanin content and LIOB threshold in this pilot study may further guide physicians, that is, physicians may be able to predict the threshold of LIOB, without having to see the clinical endpoints, by simple measurement of melanin content of the skin to treat preoperatively.

Customized Precision Facial Assessment: An AI-assisted Analysis of Facial Microexpressions for Advanced Aesthetic Treatment.

We introduced a novel protocol based on an artificial intelligence (AI)-assisted analytic system for facial expressions, Customized Precision Facial Assessment (CPFA), to evaluate and quantify the microexpressions of aesthetic concern. With the help of CPFA, physicians may be able to conduct static and dynamic assessments for the microexpressions of the ir patients and perform quantitative measurements before and after the treatments. Through the detection of microexpressions and its active action units of facial muscles, physicians are more likely to optimize the treatment with minimal intervention by precise localization of the foci of aesthetic concern. We presented 3 cases who received neuromodulators and injectable fillers, and we showed the differences in the area of treatment and outcomes of procedures between the CPFA-oriented treatments and human-facilitated ones. We found negative facial expressions decreased in all 3 cases in the group of CPFA while they decreased in only case 1 and case 2 in the group of human facilitated treatment. The CPFA group has more significant decrease in negative facial expression scores than the human group. This pilot study demonstrates that CPFA can objectively recognize and quantify the facial action units associated with negative emotions, and the physician may be able to customize the treatment for individuals accordingly with promising results.

A Novel, Optimized Method to Accelerate the Preparation of Injectable Poly-L-Lactic Acid by Sonication.

Current consensus for preparing injectable poly-L-lactic acid (PLLA) suggests adequate hydration (less than equal to 2-24 hours of reconstitution) of the lyophilized particles before injection, but the volume of reconstitution and the duration of hydration time varies. This study established a method to evaluate the distribution of PLLA particles after hydration and found that longer hydration time increased the effective portion (particles less than 60 µm) of PLLA products. Further investigation of the feasibility of reconstitution with sonication revealed that 2-hour hydration of PLLA powders with additional 5-minute-sonication could yield a comparable particle distribution with 48-hour-hydration of PLLA. Moreover, adding lidocaine into the diluent did not alter the distribution of PLLA particles. We proposed a new, feasible and efficient method of preparing PLLA injectable products: 2-hour hydration of the powders, sonication of the bottle or vial containing PLLA products for at least 5 minutes, and finalization with 1-2 mL of lidocaine immediately before injection. J Drugs Dermatol. 2018;17(8):894-898.