• adverse effects;
  • patient satisfaction;
  • pigmentation;
  • scar atrophy;
  • skin redness



Treatment of acne scars with ablative fractional CO2 laser appears to be an effective and well-tolerated treatment. However, so far the influence of treatment interval has not been evaluated.


To evaluate whether treatment of acne scars with fractional CO2 laser resurfacing at 1-month interval achieves better results with no difference in the occurrence of adverse effects, than treatment given at 3-months interval.


Patients (n = 13) with symmetrical atrophic acne scars on right and left sides of the mid-face and lower-face were randomized to two fractional CO2 laser treatments at 1-month versus 3-month intervals. Blinded on-site evaluations were performed 1 and 6 months after the last treatment on 10-point scales. Endpoints were scar atrophy, patient satisfaction, and adverse effects.


Pre-operatively, acne scars were moderately atrophic (5.86 ± 1.87). After treatment acne scars appeared with less atrophy on both treated sides 1 month postoperatively (1-month interval 1.96 ± 1.23, P < 0.0001; 3-months interval 1.82 ± 1.08, P = 0.0006) and 6 months postoperatively (1-month interval 1.56 ± 1.24, P = 0.0021; 3-months interval 1.33 ± 1.66, P = 0.0002). The treatment interval did not influence the improvement of scar atrophy at any time postoperatively (P = 0.81). Patients were moderately and equally satisfied with the treatment result on facial sides (P = 0.93). Postoperative adverse effects were minor and not influenced by the treatment interval.


Fractional CO2 laser resurfacing improves atrophic acne scars and a treatment interval of either 1-month or 3-months does not seem to influence the improvement of scar atrophy nor the occurrence of postoperative adverse effects. Lasers Surg. Med. 46:89–93, 2014. © 2013 Wiley Periodicals, Inc.