Q-switched ruby versus long-pulsed dye laser delivered with compression for treatment of facial lentigines in Asians

Abstract

Background and objectives: Q-switched lasers have been used for the treatment of lentigines but post-inflammatory hyperpigmentation (PIH) can be an issue especially in Asians. The 595 nm long-pulsed dye laser (LPDL) has been used for the treatment of vascular lesions and although it is well absorbed by oxyhemoglobin, it is also absorbed by melanin. To use this device for the treatment of facial lentigines, we attached a flat glass lens to the tip of the laser's handpiece, allowing compression of the skin during treatment. In doing so, eliminated the absorption by oxyhemoglobin. This prospective study aims to compare the efficacy and complications of such an approach to the use of Q-switched ruby laser (QSRL) in the treatment of facial lentigines in Asians.

Study design/materials and methods: Eighteen Asian patients (1 male, 17 female) with facial lentigines Fitzpatrick skin types III-IV were enrolled. One of the lentigines present was treated with LPDL by compression method and the other one was treated with QSRL. A LPDL emitting wavelength of 595 nm, spot size of 7 mm was used, with fluence between 10 and 13 J/cm(2) and pulse duration of 1.5 milliseconds. Cryogen spray cooling was not used. A 694 nm QSRL was used with a spot size of 4 mm, fluence of 6-7 J/cm(2), and pulse duration of 30 nanoseconds. Lightening of the lesions was assessed by reflectance spectrometer Erythema, hypo- or hyperpigmentation and scarring were also assessed by clinical examinators.

Results: The degree of clearing achieved with the two lasers was 70.3% and 83.3% for QSRL and LPDL, respectively. All QSRL treated areas developed erythema whereas only 4 of 18 LPDL treated areas developed erythema. Hyperpigmentation was seen in four patients after QSRL, but not after LPDL. There was no scarring or hypopigmentation.

Conclusions: LPDL delivered with a compression method is more effective than QSRL for facial lentigines. Complications after LPDL treatment were substantially less frequent than after QSRL. The addition of compression technique may allow "vascular" pulsed dye laser to be used for treating a variety of pigmented lesions.