M.O.
I've never heard of tear duct tubes, but we've experienced blocked tear ducts. Basically there's mucus that keeps a fetus' orfaces closed while en-utero. Upon birth they usually get squeezed out and open up on their own. If not, you're dealing with blocked tear ducts. We've had some open on their own and one that needed to be surgically opened.
It was a quick procedure/surgery where they essentially put a pin in the duct to unblock the tube. She was in and out before we knew it. No recovery time. We've had no problems since then.
Best wishes