Pigmentation dependent, short time skin reactions to copper vapour laser and argon laser treatment

Thirteen human volunteers selected to have a varying degree of epidermal skin pigmentation were laser treated on the inside of the brachium in six hexagonal areas; three areas with an argon laser (AL, 488, 514.5 nm) and three corresponding areas with a copper vapour laser (CVL, 578 nm). The lasers were connected to a Hexascan device and the physical settings were identical for the two laser types, except for the wavelengths. Beam diameter was 1 mm, pulse duration 200 ms, intensities 0.7, 1.0 and 1.3 W/spot, corresponding to 14.1, 20.2 and 26.2J/cm2 per treated skin area. The skin pigmentation was objectified by skin reflectance. A correlation was demonstrated between skin pigmentation and wound healing time, maximum wound area, and the acute clinical response at days 0, 1, 4, 7, 11 and 17 after laser treatment. An increased skin pigmentation resulted in increased acute and subacute skin reactions. Comparison of the AL and the CVL demonstrated that the CVL on day 0 (0.7 and 1.0 W/spot) and on day 1 (0.7 W/spot) induced a significantly higher degree of skin reactions as compared with the AL. At 0.7 W/spot the CVL induced a significantly higher maximum wound area and a significantly prolonged wound healing time as compared with the AL. An inverse reaction existed between pigmentation and the threshold intensity required to induce wound formation.