National report — Early treatment with either a 585-nm or a 595-nm pulsed-dye laser (PDL) can safely and significantly improve the appearance of surgical scars in patients with skin phototypes I-IV, according to results of a controlled trial undertaken by researchers from the University of Miami's department of dermatology and cutaneous surgery.
In a poster presented at the 63rd Annual Meeting of the American Academy of Dermatology, Keyvan Nouri, M.D., associate professor and director of Mohs, dermatologic and laser surgery, and Maria P. Rivas, M.D., research fellow, reported clinical and histological findings from a study comparing the effects of both types of PDLs with no treatment in 14 patients with 19 new, linear surgical scars. Each scar was divided into three equal fields. The central field was always left as the untreated control and the two outer fields were randomized to treatment with the 585-nm or 595-nm PDL. A total of three treatments were administered beginning immediately after suture removal and were repeated monthly.
Outcomes were assessed at one month after the last laser treatment by a blinded observer who rated features of scar appearance (pigmentation, height, vascularity) and quality (pliability) using the Vancouver Scar Scale (VSS) and judged overall cosmetic appearance using a visual analogue scale. In both endpoint analyses, PDL treatment was associated with significant benefits compared with control. There were no statistically significant differences between the two devices, although the results for both efficacy measures showed a trend for a better outcome using the shorter wavelength laser.
The prior trial he referred to was published in 2003 (Dermatol Surg 2003;29:65-73) and showed that the quality and appearance of surgical scars could be improved when treated three times with the 585-nm PDL, also starting immediately after suture removal. Benefits were seen relative to no treatment in the overall cosmetic appearance, VSS total score, and the individual parameters of scar height, erythema and pliability.
"The 585-nm and 595-nm PDLs are the two most common lasers in medical practices, and so we were interested in seeing if similarly good results could be achieved with the 595-nm device," Dr. Nouri explains.
In the current study, the two lasers were used with identical operating parameters, including a spot size of 10 mm, a fluence of 3.5 J/cm2 and a pulse duration of 450 microseconds.
Relative to baseline, mean VSS scores improved 32 percent for the control sites, 55 percent for fields treated with the 595-nm PDL, and 67 percent at the sites treated with the 585-nm laser. Results of the cosmetic appearance ratings were consistent with those outcomes. Cosmesis was rated on a scale of 0 (worst) to 10 (best). Mean scores were 7.3, 8.3 and 8.6 for the control, 585-nm and 595-nm PDL treated sites, respectively.
"Given our sample size, we were unable to detect a statistically significant difference between the effects of the two lasers. However, the results suggest the potential superiority of the 585-nm device. That benefit seems plausible because we believe the mechanism of the laser treatment is due at least in part to targeting of the vasculature, and there is higher oxyhemoglobin absorption of the 585-nm wavelength versus the 595-nm wavelength," Dr. Nouri says.
Biopsies were also obtained from three randomly selected scars. The findings from the histological evaluations were consistent with the clinical results in showing more elastin fibers in the treated versus control sites with no marked differences between tissue taken from sites treated with the 585-nm versus 595-nm lasers.