I realize I am not the one of whom you requested a reply, but I am a (primarily) cataract surgeon who co-manages with several ODs and an MD or two who have recently retired from surgery, thus are medical ophthalmologists. This issue of patients not wanting to return rarely comes up when the referring provider is highly skilled with a good bedside manner, i.e., patients trust him/her and want to return. But, as you know, it does come up occasionally, and I do not find the conversation all that awkward because of how I prep the patients pre-operatively.
In my pre-op discussion with the patient, I say, "Dr. X sent you here for a cataract evaluation. When we finish with your cataract surgery(ies), Dr. X will see you soon thereafter to take back over your care." With those expectations set, I probably have less than 1% of patients give me a hard time about not wanting to go back. And again, when I do have problems, it's almost always with patients of the one provider who has less-than-stellar bedside manner. It also helps that every patient who is referred to me signs a "co-management agreement" with his/her referring provider in which he/she agrees to return to the referring provider for the post-op care. If a patient still gives me a hard time, I tell the patient that I have given my word to and have a signed agreement with the referring providers to send patients back to them.