The primary cause of sunken cheeks is that of volume loss - that of the bony shelf that is the mid-face, as well as the deep fat pads associated with the mid-cheek. These provide support for the overlying superficial fat pads and skin.
Age brings along continuous bony and deep fat pad volume depletion, and the primary minimally invasive method of restoring volume is with the use of dermal fillers. These include hyaluronic acid and non-hyaluronic acid fillers - the choice of which should be decided after a thorough discussion with your doctor.
Restoration of the mid-cheek volume is often the first step in filler injections, and this helps improve facial structure, sagging, and even under-eye appearance.