Both implants and fillers are useful to treat the lower eyelid hollows (aka tear troughs). I usually recommend using fillers first to any interested patient, simply because it is quick, without recovery time, and temporary if patients don't like the end result. If they like it, and want more, that's when I recommend the implants. I personally prefer implants simply because the results are much more predictable, long-lasting, and are more "robust" than the fillers. Plus, the implants still can be removed if there is a problem or a patient changes his/her mind. Not all surgeons are comfortable with fillers, and the most common mistake is to overfill, so ask your surgeon if they have experience injecting that area- it can be tricky and unforgiving, and requires a cautious approach.