Pulsed and Scanned Carbon Dioxide Laser Resurfacing 2 Years after Treatment: Comparison by Means of Scanning Electron Microscopy

Abstract

Studies have reported short-term and long-term (1-year) findings for laser skin resurfacing. Two of the most popular systems used for this procedure, the continuous-wave Sharplan 40C SilkTouch system and the pulsed Coherent 5000C UltraPulse system with a computer pattern generator, were previously compared for a range of follow-up times up to 1 year, using light microscopy and transmission electron microscopy. This study analyzed the 2-year morphological differences using scanning electron microscopy. Tissue samples were obtained from 10 patients (age range, 50 to 72 years; skin types II and III) who had undergone laser resurfacing 2 years previously. One half of the face of each patient had been treated with the continuous-wave system and the other half with the pulsed system. The samples were subjected to scanning electron microscopy. On the continuous-wave-treated side, significantly better dermal collagen organization was observed at 2 years, with plump-appearing fibers that were closely knit to form a compact structure. On the side treated with the pulsed system, the collagen fibers in the papillary dermis were more loosely arranged and appeared drier. In both the continuous-wave-treated and pulsed-treated areas, the epidermis appeared healthy and exhibited some signs of age-related deterioration, with slightly flatter plaques and somewhat more flaking keratin on the pulsed-treated side. Probably because of the greater degree of residual thermal damage associated with the continuous-wave system, at 2 years after treatment there was more prolific synthesis and better orientation of collagen fibers, which were maintained for longer times, compared with the pulsed-treated specimens.

Laser resurfacing today and the “cookbook” approach: a recipe for disaster? A response

“…However, in response to Dr Fitzpatrick's comments regarding the CW vs . the flash‐scanned CO 2 , surely the final result is what we are looking for, and as my colleagues and I showed with transmission and scanning electron microscopy, at 2 years postsurgery the continuous wave (CW)‐treated skin was definitely healthier than the flash‐scanned skin 6,7 …”

Laser irradiation of the guinea pig basilar membrane

“…Evidence indicates that new collagen synthesis as well as collagen remodeling occurs in response to laser irradiation [15,16]. This does not occur immediately after laser irradiation, but instead occurs over the subsequent days to weeks in response to collagen coagulation [17].…”

“…This does not occur immediately after laser irradiation, but instead occurs over the subsequent days to weeks in response to collagen coagulation [17]. Indeed, ongoing changes can occur even up to 2 years after laser treatment [15]. In this study, we only analyzed the acute effects of laser irradiation and so the long-term consequences of this procedure are unknown.…”

Laser-induced collagen remodeling and deposition within the basilar membrane of the mouse cochlea

“…27 Studies in other tissues have shown that there are also delayed effects of laser irradiation on collagen. [28][29][30] In the subsequent days to weeks after irradiation, there is an increase in tissue stiffness as existing collagen remodels and new collagen is synthesized. Ongoing changes can occur even up to 2 yr after laser treatment.…”

“…Ongoing changes can occur even up to 2 yr after laser treatment. 28 Increases in tissue stiffness of up to 100% have been shown in tendon connective tissue after laser irradiation. 23 We hypothesized that cochlear laser irradiation would induce delayed changes in basilar membrane collagen similar to that found in other tissues.…”