My parents went through similar things with me...my eye was so far turned you couldn't see it almost from day 1.
As an infant I had several operations on my eyes, and nothing worked, simply change the direction of the turn lol. I was in glasses from 11 months. My glasses have a directional focal point in the left lense, meaning my eye is actually drawn to it, however, there has been nothing over the years that has managed to permanently bring it in line without constant effort.

There are exercises you can do and practice not looking through one eye (which you won't notice, but will become normal for bubs) but at this age that would be very very difficult to achieve.
Basically a strengthening of the muscles around the eye is needed, so patches etc can be helpful, but as I said, without constant attention and practice, the eye will turn on its own.
It is incredibly tiring to try and keep it straight, which required physically holding it place and trying to look through 2 eyes at once (which is how 'normal' people see) often results in double vision as we don't get the cross over vision that is normal, it is one eye or the other.

Anyway, I would go and have a chat to this guy and see what his methods are, but I would be VERY hesitant of handing off fists full of cash for repeat visits to use methods that will most likely need constant consistent application that in the end (or importantly with time) will not achieve permanent straightening at such a young age.

How badly is the eye turned? You may find that you can have the opthamologist instruct DD when she is about 5 + how to do the exercises and practices she needs to keep the eye as straight as possible and the muscles as active as possible (this for me has been the biggest challenge, as this lack of muscle use will lead to her yes being different shapes )

HTH