Monopolar Radiofrequency Diathermy (LVT-250, Korea) was used at average energy160-180 W, main power 50/60 Hz, 40˚C ~ 45˚C Temperature, RF output 470 kHz, 20 mm electrode size.

Flash lamp pulsed dye laser; Candela SPTL-1 (Candela Corp., Wayland, Mass.) with the following parameters: (585nm wavelength, 450 msec pulse duration, 6.5 to 7.5 J/cm² energy density and 5or 7mm spot size).

The RF electrode was moved randomly for 30 seconds over each scar. The total duration of the treatment session is only 5 minutes for each cheek. It takes 15 minutes if the forehead and 2 cheeks are affected.

Clinical evaluation scale for acne scarring. Using this scale, the type of scar was defined by the qualitative descriptions of scars, which is then accompanied by a numerical score (0-4) and then multiplied by (15-50) which is a weighting factor of clinical severity, the total possible score is from 0 to 540. Higher score means worse outcome while lower score means better out come.

Self-assessment of clinical acne-related scars questionnaire. It consists of 5-items with 1 hypothesized domain which asks patients to assess acne scars severity as seen in the mirror. The total possible score is from 0- 20. Higher score means worse outcome while lower score means better out come.

Facial acne scar quality of life scale. It is a tool formed of 10-items with 3 domains to assess the emotional, social functioning and work/school effect of scars on a 5-point rating scale The total possible score is from 0- 40. Higher score means worse outcome while lower score means better out come.