I didn't really have an undereye bag issue, but my eyes tend to sink in a bit. My doctor said that I didn't really have any fat to remove and he did not want to overdo otherwise I would look gaunt. He did some lifting of the upper lid and lifted the lower a bit. He made a good point that you do not want to lift too much from the lower lid because the lid could then turn out away from the eye.
Overall, he did an excellent job! I think that he was wise is advising me on being realistic about my expectations. My eyes do look brighter, eye makeup does not melt off like it used to. There was virtually no pain, whatsoever. I just looked like a train hit me, but no pain. Very easy recovery. Just be realistic about your expectations; you're not going to have perfectly, pulled, 20 year old eyes....hey, we do age.