Restylane Vs. Fat Grafting for Under Eye Hollows?

Fat injection, even in the best of hands, has the chance for lumpiness. This lumpiness can be difficult to correct. Especially in young patients we prefer Prevelle or Restylane.

Both fat and Restylane can be used to fill out hollows under the eyes.  Fat has the advantage of being permanent but is a bit more unpredictable.  For those who want quick fixes with little to no downtime, Restylane is the appropriate choice.  For those who want more volume and permanent results with added downtime, fat is the better option.

Although you may have heard scary things about both procedures the incidence of them happening is quite low. That being said the potential bad things that can happen from fillers are generally less severe and usually reversible when compared to fat transfer.
You are young and your lower lid contour is relatively good. I would recommend beginning with filler. You don't burn any bridges and I beleive you will be pleased with your result.

Restylane or Juvederm, both hyaluronic acids, are commonly used, off-label (not FDA approved for this use, but doctors may legally perform the procedure) for this purpose.
Fat injections may give you a good result but, there are different ways that both of these fillers are done by different doctors. Some inject over the muscle, and there may be larger chance of visible bumps.
The nice thing about Restylane or Juvederm is that if there is too much filler injected, it can be dissolved by injecting hyaluronidase. This also can be used in case of serious complications, such as a plugged blood vessel, whereas there is no equivalent of hyaluronidase for fat injections.

The key is not the procedure but who does the procedure.  Either might be appropriate for you -- and they are not the only options.  There are other fillers, biostimulators and devices that might be approrpriate.  The addition of the right cosmeceuticals can also make the difference in your results.  My recommendation is that you seek a consult with an experienced physician board certified in a core cosmetic specialty like dermatology.  Review your concerns and your goals with her and have a clear discussion about your options, risks  and benefits.  I hope this helps answer your question. Best wishes.