2.1.2　Photoaging

Skin aging is a common dermatological disease related to heredity and environment.The intrinsic aging of the skin is determined by gene.Age-related clinical features include skin atrophy，loss of elasticity，fine wrinkles，dryness and prominence of vasculature.External aging is related to the environment（e.g.，solar radiation，smoking，pollution，nutrition and lifestyle factors）.Extrinsically aged skin clinical features include deep wrinkles，rough textures，telangiectasia，rashes，and irregular pigmentation.Skin aging caused by ultraviolet is called photoaging，and ultraviolet is the most common environmental factor.Because of people's pursuit of skin rejuvenation，photoaging has become more and more concerned.In this part，we will discuss the pathogenesis，clinical manifestations，histological features，and management of photoaging.(https://www.daowen.com)