Photoaging

Photoaging or photoageing (also known as 'dermatoheliosis') is a term used for the characteristic changes to skin induced by chronic UVA and UVB exposure.:29 Tretinoin is the best studied retinoid in the treatment of photoaging Photoaging or photoageing (also known as 'dermatoheliosis') is a term used for the characteristic changes to skin induced by chronic UVA and UVB exposure.:29 Tretinoin is the best studied retinoid in the treatment of photoaging The deterioration of biological functions and ability to manage metabolic stress is one of the major consequences of the aging process. Aging is a complex, progressive process that leads to functional and esthetic changes in the skin. This process can result from both intrinsic (i.e., genetically determined) as well as extrinsic processes (i.e., environmental factors). Photoaging is attributed to continuous, long-term exposure to ultraviolet (UV) radiation of approximately 300–400 nm, either natural or synthetic, on an intrinsically aged skin. UVB rays are a primary mutagen that can only penetrate through the epidermal (outermost) layer of the skin, resulting in DNA mutations. These mutations arise due to chemical changes, the formation of cyclobutane pyrimidine dimers and photoproducts formed between adjacent pyrimidine bases. These mutations may be clinically related to specific signs of photoaging such as wrinkling, increasing in elastin and collagen damage. The epidermal layer does not contain any blood vessels or nerve endings but melanocytes and basal cells are embedded in this layer. Upon exposure to UVB rays, melanocytes will produce melanin, a pigment that gives the skin its color tone. However, UVB will cause the formation of freckles and dark spots, both of which are symptoms of photoaging. With constant exposure to UVB rays, signs of photoaging might appear and precancerous lesions or skin cancer may develop.