Some anatomical observations on midface aging and long-term results of surgical treatment.

[BACKGROUND] Controversy exists as to whether the changes of midface aging (elongation of the lower eyelid caused by infraorbital hollowing, flattening of the malar eminence, and increased prominence of the nasolabial fold) are attributable to gravitational migration of the check fat or to fat atrophy.

[METHODS] The anatomical explanation of the gravitational migration of the malar fat pad is based on previously reported magnetic resonance imaging studies of the midface cheek fat in young and older subjects and histologic studies of the superficial fascia in face-lift patients.

[RESULTS] Clinical and laboratory observation of the midface malar fat pad suggests that, during repeated movements of animation, levator muscle contraction and shortening produces tissue expansion pressures within the overlying cheek fat pad that cause the acutely prominent nasolabial fold of animation.

[CONCLUSIONS] Over time, chronic recurrent tissue expansion of the skin of the lower anterior cheek combined with stretching of the supporting intrafat pad fascial septa results in downward migration of the malar fat pad, causing infraorbital flattening and permanent prominence of the nasolabial fold. Although not the primary cause of facial aging changes, fat atrophy may contribute secondarily in those individuals whose faces become thinner as they age.