Collagen gives the skin its firmness and resilience and plays a major role in wound healing of the skin. Elastin provides flexibility, which enables the skin to extend and return to its original shape after it has been stretched or compressed. As part of the aging process, collagen and elastin production slow down and these support structures become weak and loose. As the skin becomes more brittle and inelastic, under eye wrinkles and other fine lines emerge. Several factors affect the emergence and severity of fine lines and wrinkles, including genetics, gender, photo-aging (sun-induced aging) smoking, repeated facial expressions and nutrition.