The researchers will evaluate changes in the dermis and skin properties as the effect of treatment with Tretinoin cream (0.1%) by using the following optical imaging techniques.~Multiphoton microscopy using a clinical tomograph (MPTflex, Jenlab, Germany)~Multispectral Imaging using a device developed at Beckman Laser Institute, UC Irvine
The researchers will assess the effects of treatment with tretinoin cream on human skin by using non-invasive optical imaging technologies.