Personally, I would forget about trust issues and focus on eye medications. If you have to muscle her around some, so be it; taking care of the eye takes precedence.
With Nicky's eye, the vet showed me how and made it look so easy; and I actually did o.k. for a couple days. Nicky would try to rear, but I was so worried about his eye, I tied him up short and if he tried to rear, I just pushed down on him. But after a few days, he'd squinch his eye shut and wouldn't open it. ...no matter what I did. It was kind of funny (in retrospect) his eye's about to fester out of his head and there he is squeezing his eye shut at med. time. ....never did solve that one, since about that time vet had me check him into the hospital.