Inclusion Criteria:  Women aged 18-60 years old with an understanding of all the information given by written consent form Had undergone priming with tretinoin cream 0,05% for 2 weeks pre fractional CO2 laser treatment  Exclusion Criteria:  Personal or family history of skin cancer, especially melanoma Consumption of systemic retinoic acid within 3 month of enrollment Use of any topical skin brightening or whitening preparations within 1 month of enrollment Pigmentary disorders or any dermatoses, which may affect the measurement within the study areas A pregnant or breastfeeding mother History of hormonal or endocrine diseases or taking medication for hormonal or endocrine diseases Inability to comply research protocols