How invasive and effective is an eustacioplasty operation? my left ear feels as if it's full of water, and my doctor thinks the tube has calcified.

ET dysfunction: Any type of eustachian tube repair or "plasty" is relatively non-invasive but realize these are not necessarily proven treatments. The data are not out to truly support these types of procedures. It is a problem that can plague ENT patients and there is not yet a great solution. Many ENT md's still rely on rx and ear tubes for their patients. Maybe seek a second opinion.

Controversial : I am not aware of a definitive operation directly on the eustchian tube. You may want to get a second opinion from an otologist.