After being informed about the study and potential risks, all patients giving written informed consent will undergo a 24 hour screening period to determine eligibility for study entry. Upon enrollment, patient who fulfill all the inclusion criteria and does not fulfill any exclusion criteria will be scheduled for their visits.~All subjects will be receiving two sessions of treatment, with the two sessions 8-12 weeks apart. Subjects' face will be divided to left and right, with each side randomized to receive a low versus high energy setting. In the low energy setting side of the face, central base of boxcar scar will be treated with 20mJ, while shoulder of scar will be treated with 50 mJ. In the high energy setting side of the face, central base of boxcar scar will be treated with 30mJ, while shoulder of scar will be treated with 60 mJ. Subject will be blinded regarding which side of the face received low versus high energy setting.~Ultrasound will be used to assess epidermal and dermal thickness change at the treated area. This will be performed before the 1st and 2nd treatment session as well as one month and three month after the 2nd treatment session.~Antera Quantitative 3D Image Analysis will be performed before and after the 1st and 2nd treatment session as well as one month and three month after the 2nd treatment session.~3mm punch biopsy will be taken from 10 volunteers over bilateral face before the 1st treatment session and 3 month after the 2nd treatment session (total of 4 sample will be obtained in each volunteer). Skin specimen will be stained with hematoxylin and eosin as well as relevant stain for collagen and elastic fiber.~Clinical photograph will be taken before and after the 1st and 2nd treatment session as well as one month and three month after the 2nd treatment session. Two blinded board certified dermatologist will be asked to rate the improvement of acne scar by GSAAS according to the clinical photograph taken.~All subjects will be asked to rate their satisfaction regarding treatment response over each side of the face using a 0 to 10 point scale chart.
Purpose of the study is to assess the effect and evaluate topographic volume changes of UltraPulse at treating boxcar scars with different energy and the effect of UltraPulse at treating icepick scars.