Physicians should approach a patient seeking cosmetic improvement of the signs of aging from an anatomic standpoint. To appreciate facial symmetry and balance, one commonly used practice is to divide the face horizontally into thirds. The upper third ranges from the trichion to the glabella, the middle third from the glabella to the subnasale, and the lower third from the subnasale to the menton. Filler substances are mainly applicable, either alone or in combination with other treatment modalities, to the lower two-thirds of the face.
Upper third of the aging face
Changes in the upper third of the face are primarily related to chronic ultraviolet light damage, to the intrinsic muscles of facial expression and their influence on the skin, and to gravitational changes from loss of elasticity of the tissue. Occasionally filler substances may be used in conjunction with botulinum toxin to soften hyperdynamic wrinkles after the underlying causative muscles have been paralyzed.
Middle third of the aging face
Aging of the middle third of the face affects the eyelids and periorbital regions, the cheeks, and the nose. These changes primarily result from a combination of photo-aging, loss of subcutaneous tissue, loss of cutaneous elasticity, and remodeling of underlying cartilaginous and bony structures.
Aging of the periorbital tissues results in both cosmetic and functional impairments. Dermatochalasis results from the combination of progressive cutaneous inelasticity of the eyelids and the effects of gravity. In severe cases, the upper eyelid skin may become so redundant that the visual fields are impaired. The canthal tendons and the tarsal plates provide the support structure of the eyelids, and loss of elasticity of these structures results in decreased lid tone and ability to ’snap back’ after stretching of the eyelids. In severe cases, stability of eyelid position may be affected, resulting in either ectropion or entropion. The orbital septum may weaken over time, allowing for protrusions of the upper and lower lid fat compartments; however, some people may experience a loss of periorbital subcutaneous tissue, resulting in a ’sunken-in’ skeletonized appearance to the orbits.
The cheeks may be affected by volume loss of the buccal fat pad, which is positioned between the masseter muscle anteriorly and the buccinator muscle posteriorly. In childhood, an ample buccal fat pad contributes to the fullness of the cheeks; however, with age this fat pad atrophies. A buccal depression may develop, leading to the appearance of prominent malar eminences.
Aging of the nose results in both structural and surface changes. The support mechanisms of the nasal tip may become inelastic and stretch with age, resulting in nasal tip ptosis and an apparent elongation of the middle third of the face. The fibrous attachments between the inferior margin of the upper lateral nasal cartilage and the superior margins of the lateral crura of the alar cartilages elongate from a combination of gravity and remodeling of the underlying bony and cartilaginous tissues. Additionally, the sling supporting the dome area weakens and there is loss of subcutaneous tissue, resulting in nasal ptosis, a downward and posterior rotation of the nasal lobule, retraction of the columella, and prominence of the nasal hump and cartilages. On the surface, enlargement of sebaceous glands may alter the skin texture, resulting in a rhinophymatous appearance.