As the human face ages, the loss of volume can be
striking, resulting in deep furrows and wrinkles.  The human
eye perceives these depressions in the skin due to the captured
light in the ‘valleys’ of the face. It is this retained light, in the
form of linear shadows that leads us to estimate age accurately.
To correct the problem, and render a patient looking more
youthful, these deep areas must be addressed. Two routes to correction exist.  

For years few options existed for correcting mid and lower
face aging, other than invasive surgery. Facelifts and other
surgical corrective measures pull the skin taut; much like a
bed sheet that is bunched up is rendered flat by stretching from
the edges. The other method to eliminate wrinkles is to fill in
the valleys, taking away the low spots by filling them with a
form of injectable filler. This simpler, office-based alternative
offers less downtime, but with visible results. One of the earliest
options, collagen, was a viable choice, but had the disadvantage
of required testing to verify absence of allergic response.
However, recent advances in dermal filling technology are in
the form of hyaluronic acid derivatives, which are well tolerated
and require no advance testing. Restylane, Juvederm, Captique,
and Perlane are brand-name fillers in the hyaluronic acid family.