The purpose of this study was to compare the efficacy and safety of the 532 nm long-pulsed laser (10 ms) with that of the 532 nm short-pulsed laser (10 ns) for freckle removal. Currently, the gold standard for treatment is the short-pulsed laser. Recently, several long-pulsed lasers have been introduced for both hair removal and the treatment of freckles. To our investigative team's knowledge, no controlled experiments have been performed to compare the safety and efficacy of long-pulsed versus short-pulsed lasers for the treatment of freckles. This was a 4-week trial, and all patients had three freckles that were randomly allocated to be treated with short-pulse laser, long-pulse laser, or to receive no treatment (control). All patients had three freckles that were randomly selected to be treated with short-pulse 532 nm Medlite IV laser (10 n, 1 J/cm2), or long-pulse 532 nm Aura laser (10 ms, 1 J/cm2) or to remain as a control (no treatment). The laser treatment was only performed once, followed by a 1-day and a 1-month follow-up visit. Freckle size was determined by a novel surface area measurement technique that was created by our research staff. The study included 17 sets of freckles (three in each set). All of the lesions which received the short-pulsed laser treatment had immediate whitening of the lesions, which turned into dry scabs the next day. None of the freckles treated in the long-pulsed group or control group developed immediate whitening or scabs. No blisters or ulcers developed. The average pain score in the short-pulsed laser group was 2-3 out of 10, while it was 0 out of 10 in the long-pulsed laser group. All scabs that developed in the short-pulsed laser group fell off between days 6 and 12 (average 8 days). The outcome of this study verified the appropriate treatment of freckles. The study confirmed that when the same energy settings, short-pulsed laser is the more effective laser treatment regimen (when compared with the long-pulsed laser), with high tolerability and minimal side effects for patients with skin types I to IV.
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