The changes in facial appearance that reveal aging involve alterations in the pigmentation of the skin, a loss of dermal elasticity, the appearance of wrinkles and loss of facial volume. Due to particular characteristics of the tissues that surround the eye, the periorbital area is one where features of aging are especially likely to be present. One significant factor is that the skin overlying the blephara is extremely thin, only 0.3 to 0.5 mm thick. Only in a few other regions is such thin skin seen. The blepharal skin lacks subcutaneous fat, which may disguise any eyelid irregularity and compensate for prolapsed adipose tissue, which often appears as patients grow older. The delicate nature of the skin in this region means it is somewhat transparent, so pigmentation (whether of the skin or from circulating molecules), muscle alterations and blood vessels may all appear on the eyelid. The dermis contains fewer collagen and elastin fibres than elsewhere in the body; thus, this region is more susceptible to damage, including the development of wrinkles. Furthermore, the blepharal skin and the skin around the eyes move a great deal, with the muscles of facial expression, such as the corrugator, orbicularis oculi and procerus, exerting a force on it virtually continuously. This may explain why rhytides develop early in this region of the face.