Eyelid festoons and malar mounds are cosmetic flaws degrading the appearance of, primarily, the lower eyelid (yes, upper lid festoons have been described). They are grouped together here because they share a main causative factor - thinning and fraying of the orbicularis muscle, the eyelids' large closing muscle encircling the eyes and rim of bony socket.
The orbicularis muscle (A and B) encircling the eyes
The orbicularis muscle serves to shut the eyes by contracting much like a sphincter muscle that contracts from all sides inward towards the center. As an important part of the blinking mechanism, the muscle helps to protect and nurture the eye, support the eyelids, and direct tears in the proper direction.
Over time, the concentric fibers of the muscle may become flimsy, stretched, frayed, and detached from either or both the overlying skin and underlying fascia due to use (i.e., aging), abuse (e.g., smoking, deep rubbing, constant squinting), and/or hereditary factors (yes, these conditions tend to cluster in families).
Extreme orbicularis stress from squinting
Once so damaged, the muscle may come to hang down like a deflated sail and create a variety of nightmare distortion and bulges that do not go away after standard blepharoplasty surgery. Often called "bags on bags" because their bulging may be addition to the much more common fat bags seen in the lower eyelid, they are hard to treat and amazingly resistant to even the most expert attempts to efface them.
Festoons are the most extreme of the two maladies. They come in all different sizes, shapes, and locations, hanging down like pouches starting anywhere from just below the lashes to below the rim of bone beneath the eye. They can exist as a single pouch or multiple pouches as different levels.
Upper and two lower eyelid festoons
with no sign of bulging fat
Less prominent festoons with
fat bags above: "bags on bags"
Festoons are treated by separating a flap of damaged muscle away from overlying skin and deeper fascia, resecting the most damaged muscle filling the pouch, and then reapproximating the remaining muscle with suture. The initial incision to enter the lid is similar to that used for transcutaneous blepharoplasty but may be smaller if endoscopy is employed.
Trying to correct the problem by more aggressive skin-resection during blepharoplasty doesn't work that well and is more likely to pull the eyelid away from the eye (ectropion) and/or down (eyelid retraction).
Some surgeons have begun employing a means of treatment that is much easier and quicker: burning the skin using an ablative laser, such as carbon dioxide or erbrium:yag lasers. Scarring may be less than with direct excision and the amount of skin shrinkage can be adjusted over several sessions.
Malar mounds are not as big a cosmetic issue as festoons (well, not unless you're the one who has them). They appear under the skin as fleshy, ill-defined pin-cushion shaped prominence that is positioned over the malar bony prominence (in the area marked "B" in the top anatomic photo), more like a pad than a pouch.
The mounds are caused by fat and connective tissue that insinuates itself between the fibers of the underlying orbicularis muscle in the malar area and may make contact with deeper orbital fat in back of the muscle and orbital septum. Some fibers of the orbicularis muscle may become partitioned away from the main body of the muscle. Malar mounds may exist is size from barely perceptible to quite severe and may coexist and merge into festoons located closer to the nose.
Most malar mounds are corrrected in a manner similar to but not as elaborate as used for festoons. Any protruding fat is trimmed away from under a skin flap and any identifiable muscle defect is closed. Alternatively and in contrast to festoons, the problem may be eliminated or at least greatly diminished by elevating and tightening the soft tissues above and to the side of the mound as is often provided during most facelift or, to a lesser degree, canthoplasty.
In actual practice, the surgery on these two thorny defects is more complex than presented above but the description here captures the gist of it. What's most important to take away is that such issues require special attention above and beyond that provided during standard blepharoplasty.