Hyaluronic acid fillers are injected into the fat pads just beneath the trough to remove or lessen tear troughs. Filling this pad lifts the skin and pulls the trough crease taught.
We never inject filler directly into the trough because the region beneath the tear trough skin is not ideally suited to holding the injected filler. In fact, filler injections into this region can be dangerous if not handled by an experienced physician.