Laser Treatments in Early Wound Healing Improve Scar Appearance

A Randomized Split-wound Trial With Nonablative Fractional Laser Exposures vs. Untreated Controls

K.E. Karmisholt; C.A. Banzhaf; M. Glud; K. Yeung; U. Paasch; A. Nast; M. Haedersdal


The British Journal of Dermatology. 2018;179(6):1307-1314. 

In This Article

Abstract and Introduction


Background: In recent years, various lasers have increasingly been applied during wound healing to minimize scar formation. However, no consensus regarding treatment procedures exists.

Objectives: To assess scar formation clinically after three nonablative fractional laser (NAFL) exposures, targeting the inflammation, proliferation and remodelling wound healing phases in patients vs. untreated controls.

Methods: A randomized controlled trial was performed using a split-wound design to assess excisional wound halves treated with 1540-nm NAFL vs. no laser treatment. Three NAFL exposures were provided: immediately before surgery, at suture removal and 6 weeks after surgery. NAFL exposures were applied using two handpieces, sequentially distributing energy deeply and more superficially in the skin (40–50 mJ per microbeam). Evaluated at 3 months of follow-up, the primary outcome was blinded, on-site evaluation using the Patient Observer Scar Assessment Scale (POSAS total; range from 6, normal skin to 60, worst imaginable scar). Secondary outcomes comprised blinded evaluation on the Vancouver Scar Scale (VSS) and standardized assessment comparing scar sides, carried out by blinded on-site, photo and patient assessments. This trial was registered with (NCT03253484).

Results: Thirty of 32 patients completed the trial. At the 3-month follow-up, the NAFL-treated scar halves showed improvement compared with the untreated control halves on POSAS total: NAFL treated, median 11, interquartile range (IQR) 9–12 vs. control, median 12, IQR 10–16; P = 0·001. The POSAS subitems showed that the NAFL-treated halves were significantly less red and more pliable, and presented with smoother relief than the untreated controls. VSS total correspondingly revealed enhanced appearance in the NAFL-treated halves: median 2, IQR 1–2·5 vs. control, median 2, IQR 1·75–3, P = 0·007. The standardized assessment comparing appearance of scar halves demonstrated a low degree of correspondence between on-site, photo and patient assessments. NAFL-treated scars were rated as superior to untreated scars by 21 of 29 patients.

Conclusions: NAFL-treated scars showed subtle improvement compared with untreated control scars.


Innumerable surgical procedures are performed daily, with scarring being their inevitable consequence. Postoperative scar tissue has the potential to be symptomatic and mutilating and to restrict movement, all of which may compromise quality of life.[1,2] To address this, a range of procedures such as optimized surgical techniques, compression and wound dressing are used to minimize scar formation.[3,4]

Laser treatment of scars has been used for decades and established methods aim at remodelling mature scar tissue older than 1 year.[5,6] As conventional laser techniques may not completely normalize mature scar tissue, a preventative approach consisting of laser exposure during the wound healing process has emerged. Laser treatment of wounds may induce a shift towards a regenerative process, as seen in the scarless healing during early fetal life, and thus promote reduced scar formation.[7,8] The concept of early laser intervention to reduce scar formation has already been investigated in several clinical studies, but no consensus regarding treatment procedures exists.[9–12]

In the wake of the development of fractional laser technology,[13] nonablative fractional lasers (NAFLs) and ablative fractional lasers (AFLs) have increasingly been used in scar-reducing regimens. The fractions of thermal injury provided by AFL and NAFL devices may induce a beneficial wound healing response consisting of various cytokines, including heat shock proteins, transforming growth factor-β and matrix metalloproteinases. This upregulated cytokine environment is believed to benefit skin healing by improving the distribution and quality of collagen fibres in the dermis.[14–16] NAFL creates columns of coagulated tissue in the skin with no or minor disruption of the epidermis, unlike AFL treatments, which typically disrupt the epidermal barrier.[14]

Compared with a fractional ablative skin response, a nonablative skin response possesses some advantageous properties, including lower likelihood of prolonged erythema, dyspigmentation or secondary infection. NAFL may thus be preferred for wound treatment.[17,18] A previous study showed that a single NAFL treatment applied 1 day prior to, immediately after or 2 weeks after wounding provided significant improvement in scar formation compared with untreated scars.[19] However, repeated NAFL treatments as an integrated part of surgical procedures and postsurgical care have yet to be examined. This randomized controlled trial explored the clinical effect of targeting surgical wounds with NAFL in all three wound healing phases compared with untreated control wounds. Thus, NAFL was applied immediately before surgical wounding, after suture removal and 6 weeks after surgery in an effort to target the wounds during inflammation (0–3 days), proliferation (4–21 days) and remodelling (21 days to 1 year).