Comparison of four carbon dioxide resurfacing lasers. A clinical and histopathologic evaluation.

BACKGROUND Several high-energy, pulsed and scanned carbon dioxide (CO2) lasers are currently available for cutaneous resurfacing. Although each laser system adheres to the same basic principles of selective photothermolysis, there are significant differences between lasers with respect to tissue dwell time, energy output, and laser beam profile. These differences may result in variable clinical and histologic tissue effects. OBJECTIVE The purpose of this study was to examine the in vivo clinical and histopathologic effects of four different high-energy, pulsed or scanned CO2 resurfacing lasers. METHODS A prospective study using four different CO2 resurfacing lasers (Coherent UltraPulse, Tissue Technologies TruPulse, Sharplan FeatherTouch, and Luxar NovaPulse) was performed. The cheeks of seven patients were divided into four quadrants. Each quadrant was randomly assigned to receive treatment with one of four CO2 lasers. Skin biopsies were obtained intraoperatively from each quadrant, after each of three laser passes, and at 1 and 3 months postoperatively. Blinded clinical assessments of each laser quadrant were made at 1, 3, and 6 months postoperatively by three physicians. Degree of lesional improvement as well as erythema severity, re-epithelialization rates, and presence of side effects were recorded. Blinded histologic examination of laser-treated quadrants was performed to determine the amount of tissue ablation, residual thermal damage, inflammation, and new collagen synthesis. RESULTS The four CO2 lasers produced equivalent clinical improvement of rhytides and scars. Re-epithelialization occurred in all laser quadrants by day 7. Postoperative erythema was most intense in the quadrants treated by UltraPulse and NovaPulse; however, overall duration of erythema was equivalent for all four laser systems (3 months). Postinflammatory hyperpigmentation was the most frequently encountered side effect and occurred with equal frequency in each quadrant. No scarring, hypopigmentation, or infections were observed. After one laser pass, histologic examination revealed partial ablation of the epidermis with the TruPulse laser and complete epidermal ablation using the UltraPulse, NovaPulse, and FeatherTouch laser systems. The greatest degree of residual thermal damage was seen after FeatherTouch and NovaPulse laser irradiation. New collagen formation was greatest in the UltraPulse and FeatherTouch laser-irradiated quadrants. CONCLUSIONS Equivalent clinical results were observed using the FeatherTouch, NovaPulse, TruPulse, and UltraPulse CO2 lasers. While postoperative erythema intensity differed between laser systems, total duration of erythema was equivalent. The four lasers under study resulted in minimal residual thermal damage and stimulated new collagen formation within 6 months after treatment.