I'm interested because recently I found an old book from the 19th century on google books.
I have some hearing problems left over from an ear infection, and was wondering if Iodine could help so I had googled for something like
"iodine Eustachian tubes".
Anyway, this book (written by a doctor, apparently) described several cases where he had cured recently-acquired (but not long-standing) hearing loss with iodine.
I think he was using tincture of iodine. Lugol's, although possibly invented by then, may not have been in wide use at that time. (I think this doctor was English).
His various patients (who seemed to be from humble stations in life, by and large) often seemed to have all sorts of problems, not just hearing, and the Iodine seemed to help with all the problems, including recent-onset hearing loss.
It is not always clear from the book exactly what was wrong with their hearing, and maybe he often didn't really know, but Iodine usually worked in any case.
Although I've started to use Lugol's internally, I have also been tempted to use it, dilute, as ear drops, although haven't quite had the courage to try yet. I was seeking some evidence that this might help.
Even with just oral, I think I've noticed some slight improvement in my tinnitus (which is actually long-standing, although it got worse when I had the ear infection). The more obvious infection was months ago. However, I'm wondering if I still have an underlying low-level infection that is taking its time to die off.