title: Ablative fractionated CO2 laser treatment of photoaging: a clinical and histologic study.
abstract: BACKGROUND
  Ablative fractional photothermolysis (AFP) has been reported to be effective for changes in skin pigmentation and texture associated with photoaging.
  
  
  METHODS
  A prospective study for the treatment of photoaging using a fractionated ablative carbon dioxide laser in 10 subjects. Assessment of laser efficacy was made using two modalities: histologic examination of skin biopsies and blinded physician clinical photographic assessment. For the histologic portion of the study, patients were randomized to treatment with the device at settings of pulse durations of 500, 1,000, 1,500, and 1,800 μs. Depth of injury was assessed based on histologic evaluation of depth of thermal coagulation. For the clinical portion of the study, treatment was administered to the face using a carbon dioxide laser at settings of 30 W, 500-μm pitch (density of treatment equivalent to ablation of 25% of the skin), and variable pulse duration of 1,000 to 1,500 μs.
  
  
  RESULTS
  The mean score for dyschromia had improved 47.5% (95% confidence interval (CI) = 44.1-50.9%), for skin texture 56.0% (95% CI = 51.9-60.1%), for skin laxity 56.0% (95% CI = 51.3-60.7%), for rhytides 52.5% (95% CI = 48.3-56.7%) and for overall cosmetic outcome 61.5% (95% CI = 56.4%,66.6%) 6 months after treatment. Histologic data revealed a proportional increase in depth of thermal coagulation at each pulse duration. The mean ablation depth was 283 μm for a pulse duration of 500 μs, 375 μm for 1,000 μs, 767 μm for 1,500 μs, and 1.05 mm for 1,800 μs.
  
  
  CONCLUSIONS
  We present a histologic analysis documenting the correlation between longer pulse duration and ablation depth using an AFP device. We identified that pulse duration settings up to 1,800 μs could be used safely with an ablation depth up to 1.1 mm, correlating with injury into the deep reticular dermis.
authors.affiliation: Dermatologic Surgery, Laser and Skin Surgery Center of Indiana, Carmel, Indiana, USA.
authors.forename: Emily P
authors.initials: EP
authors.lastname: Tierney
authors.forename: C William
authors.initials: CW
authors.lastname: Hanke
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Petersen
mesh_terms: D000368:Aged; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D054020:Lasers, Gas / Q000627:therapeutic use*; D028022:Low-Level Light Therapy / Q000379:methods; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000528:radiation effects; D015595:Skin Aging