Lack of difference in the rates of hypopigmentation with 90-microsecond pulsed and longer dwell time carbon-dioxide laser resurfacing.

[BACKGROUND] Hypopigmentation is an adverse outcome associated with carbon-dioxide (CO(2)) laser resurfacing. A 90-microsecond pulse produces a more favorable postoperative course of healing, erythema, and pain compared with a 900-microsecond dwell time. The rate of hypopigmentation after 90-microsecond pulsed CO(2) resurfacing may also be reduced. To date, there have been no comprehensive reports on the effect of varying pulse duration on the occurrence of hypopigmentation.

[OBJECTIVE] We sought to investigate the relationship between pulse duration and the occurrence of hypopigmentation after CO(2) laser resurfacing.

[METHODS] We conducted a retrospective review of 447 consecutive patients who were treated with a 90-microsecond pulsed CO(2) laser (n = 229) or a continuous wave CO(2) laser with a modifiable dwell time (100-950 microseconds, n = 218). Follow-up ranged from 8 to 61 months (median: 27).

[RESULTS] A series of 4 threshold dwell times (range: 90-950 microseconds) were used to divide patients into 2 treatment groups (above and below) at each threshold. The rates of hypopigmentation between groups were similar (range: 6.37%-9.09%) and serial chi-square testing revealed no statistical differences between groups for each dwell time tested (P < 1.0).

[CONCLUSION] No significant relationship between pulse duration and the occurrence of hypopigmentation was observed.