7% Lidocaine/7% Tetracaine Cream Versus 2,5% Lidocaine / 2,5% Prilocaine Cream

The treatment area will be divided in two equal parts with white markings. Between these two areas an area of 1 cm will be marked. This area will be left untreated, to avoid possible spill-over effects of the two anaesthetic creams. A thick layer of 2,5% lidocaine / 2,5% prilocaine cream will be applied on one side to the intact skin under plastic occlusion (average of 1,5-2g per 10 cm2) 60 minutes before laser treatment.

The treatment area will be divided in two equal parts with white markings. Between these two areas an area of 1 cm will be marked. This area will be left untreated, to avoid possible spill-over effects of the two anaesthetic creams. A thin layer of 7% lidocaine / 7% tetracaine cream (1mm) will be applied on the other side to the intact skin (average of 1,3g Pliaglis per 10 cm2) 60 minutes before laser treatment.

Acne keloidalis nuchae: during this study a 1064 nm Nd:yag laser with a spot size of 7-10 mm, and a fluence of 35-60J/cm2, (depending on the effective and safe clinical response), a pulse duration of 20-35 ms and 2 passes will be used.

Tattoo removal: we will use a 3 mm spotsize and a fluence depending on the absorption of the laser light, which is visible as skin whitening.