Dermatology and Aesthetic Medicine Applications

b]15.1 Effects of LLLT on Skin 15.1.1 Skin rejuvenation Skin aging is a process that can present itself relatively early on in life, sometimes even as soon as 20 - 30 years of age. Common signs and symptoms associated with skin aging include skin wrinkling, skin dyspigmentation, telangiectasia, and reduced tissue elasticity. At the histological and molecular level, common noticeable features include a reduction in collagen content, fragmentation of collagen fibers, elastotic degeneration of elastic fibers, the appearance of dilated and tortuous dermal vessels, disorientation and atrophy of the epidermis, and up-regulation of matrix metalloproteinases (MMPs), especially MMP-1 and MMP-2. Skin aging can be influenced by both time (normal aging) and environmental factors, but the single most influential factor responsible for accelerated skin aging is believed to be ultraviolet (UV) radiation-induced photodamage.