Is nanofat transfer to the under eyes safe? Will it need to be repeated to get good results?

Hey, i am getting a nanofat transfer under my eyes, and at the same time possibly a little fat in the tear trough area. Is the tear trough a safe place if only a small amount of fat is injected there? Is this something that often needs to be repeated to get a good result? I have read some people say that it's a bad idea, but shouldn't the amount of fat injected make the difference, along with the surgeon's skills?