My response was too long to post all at once, so I had to break it up.
This may not sound ideal, but sometimes trying to force fusion on a patient that has had a tropia for years doesn't work, and also, many people cannot deal with two distinct, yet clear images and often they have trained themselves to accept only one at a time, and so the blur associated with looking into the periphery of a PAL is welcome. Surgery may also be an option. The desires of the patient and his/her willingness to try options are key here. With amblyopia, where the patient's brain has basically "turned off" the eye, there's not much to be done. Perhaps a nice balance lens?
I reposed the question in the general forum, because there are a lot of others out there; many far more experienced than I am. You can follow it here: http://www.optiboard.com/forums/show...594#post407594
Hmm, here's my take on that. It depends on a lot of things, and some experimentation may be needed.
With phorias, I measure each eye individually, straight on, and use the pd I get from that. Tropias can be more problematic, as the deviation is there full time, unlike with a phoria. In my experience, someone with an eso/exo-tropia will tend to use one eye at a time, sometimes using one for near and one for far far depending on strength of rx in each eye, but primarily using whichever is dominant. The use of prisms may or may not assist with fusion, and this often depends on how long the person has had the issue, and how long they have been adapted to it. These are things that the doc and you will need to discuss with the patient. With all of that said, I usually end up following the same procedure as with a phoric eye, and the patient is left using one eye or the other.