Under eye pads or puffiness are complicated because there are several different causes and sometimes they coexist together.  So....... causes can be:

1.  The skin on the eyelids loses collagen and elasticity from sun damage and intrinsic aging causing it to not snap back well after puffiness from a salty meal, too much alcohol, etc.;

2.  The fat pads under the eyes slip or move a little causing an irregular contour;

3.  The orbicularis oculi muscle around the eyes can loosen a bit and sag;

4.  The supporting skin around the eyes, fat pads, and even bone can lose volume gradually causing sagging.

The sun damage is a  gradual process which you can help prevent with an eyelid sunscreen (see SkinTour products), and you might consider trying different eye creams to find one that's helpful for you.  Creams can occasionally aggravate the puffiness.  Also, an eyelid Thermage treatment to tighten the skin a little may help.  Your dermatologist can give you advice.   Dr. I