Evaluation of Picosecond 755-nm Alexandrite Laser With a Diffractive Lens Array on Pore Size Reduction

December 2021 | Volume 20 | Issue 12 | Original Article | 6199 | Copyright © December 2021

Published online November 22, 2021

Alison Tran MD/EdMa, Rhonda Q. Klein MD MPH FAADb, Deanne Mraz Robinson MD FAADb,c

aMount Sinai Hospital, Department of General Surgery, New York, NY
bModern Dermatology of Connecticut, Westport, CT
cYale School of Medicine, Department of Dermatology, New Haven, CT

Objectives: Medications, lasers and light therapy have all been shown to transiently minimize pore size. Current research of the 755-nm Alexandrite picosecond laser (Cynosure, MA) on pore size shows differing results regarding the efficacy, with one study of Asian volunteers (Fitzpatrick skin type IV) reporting “marked” improvement of pores, yet another study reporting no significant improvement in pore size in Chinese patients (Fitzpatrick skin type III–IV), causing some contention. This study aims to rectify the discordant results through the examination of the 755-nm Alexandrite picosecond laser on pore size reduction in a sample consisting of Fitzpatrick skin type I–III.
Methods: Patients who received 755-nm Alexandrite picosecond laser treatment for photorejuvenation, (6 mm lens array) with a fluence of 0.71 J/cm2 of the face or head, with at least two treatments over four-week intervals were included in the study. A precision subject imaging system (Canfield VISIA® Complexion Analysis Generation 7, NJ) was used to assess three parameters of pore size (feature count, score, percentile rank) at each time period at right lateral, left lateral and frontal views. A Wilcoxin signed rank test was performed to compare differences between time periods and a mixed model ANOVA was utilized to account for patients who received less than three treatments. Significance level set to P=<0.05.
Results: 32 participants met criteria and underwent at least two picosecond laser treatments for photorejuvenation. There was an overall reduction in pore count in approximately 57% of participant data points from times 1 to 2 and 50% reduction from times 2 to 3. There was a 100% pore count reduction observed from baseline compared with the follow-up visit four weeks after the third treatment, at time 4. Further, there was a significant improvement of pores demonstrated by score from times 1 to 3 (Z= -2.197, P=0.028) as well as percentile rank between times 1 and 2 (Z= -2.070, P=0.038) and times 1 and 3 (Z= -2.201, P=0.028).
Conclusion: Future studies should investigate the longterm effect of 755-nm Alexandrite picosecond laser on pore size reduction as continued patient recruitment and data collection is necessary to effectively discern the 755-nm Alexandrite picosecond laser debate. Thus, prolonged follow up post treatment should be evaluated in order to determine if results are maintained. Nonetheless, the 755-nm Alexandrite picosecond laser shows promising results for the improvement of skin pores thus far.

J Drugs Dermatol. 2021;20(12): doi:10.36849/JDD.6199


Skin “pores” (SP) are visible topographic depressions at the tegument surface that correspond to the ostia of pilosebaceous follicles or eccrine sweat glands. They are most commonly located on the face.1 The term “pore” is a misnomer as these funnel-shaped cutaneous depressions may macroscopically appear as apertures, but they are not true orifices.1 SP are benign and physiologically present in all individuals but may become a cosmetic concern when perceived as enlarged. Both endogenous and exogenous factors such as sex, genetic predisposition, aging, hormonal factors, chronic ultraviolet exposure, comedogenic xenobiotics, acne and seborrhea are known causes of pilosebaceous pore enlargement.2,3

Treatment modalities ranging from medications (eg, tazarotene cream, isotretinoin, glycolic acid peeling), light therapy (eg, intense pulse light) and lasers (eg, Nd:YAG, Clear + Brilliant® fractionated) have all been shown to transiently minimize pore size.4-7 In 2012, the first picosecond laser (PicoSure®, Cynosure, Westford, MA) was FDA cleared for the treatment of unwanted tattoos/pigmented lesions.8 The picosecond laser’s pulse duration of 1/1000th of a nanosecond effectively generates more photomechanical than photothermal effects and simultaneously minimizes collateral thermal damage.9 The diffractive lens array (DLA) was developed to effectively deliver intensified picosecond energy in a fractionated manner while maintaining a high safety profile through low total fluence.10 The diffractive lens comprises individual lenses organized in an array with 500-um center-to-center spacing, which enables the redistribution of energy into high-fluence microbeams at a fixed spot size.11 When used in conjunction with the picosecond Alexandrite laser, 70% of the energy is delivered into these high-energy zones while the residual energy is distributed over a low fluence background.11