People are always talking about following the conductor in the performance. This is something I always find puzzling. In my first professional season--remember my professional experience is not particularly significant--I performed without contact lenses which basically means I couldn't have seen the conductor even if I'd wanted to. The next season I had contacts, all paid for by the German health system. The most important reason I needed contacts was because my face had a kind of blank expression due to the fact that I couldn't see anything. Everyone said that with contacts I looked like I was actually seeing something. From my point of view it kept me from falling over things.
I recently discussed the talking prompter we used, but I can honestly say I never heard her either. I have no sense of any of this being a problem. In the rehearsals you need to see the conductor to find out what he's doing. In the performance you sing with the music, not the conductor. Whatever the music is doing, you do that too. Occasionally cues are required.
If you are not adequately rehearsed, that's another story. I remember Angela Gheorghiu's concert in Zellerbach where she kept turning to see the conductor. She didn't trust him. That's the only explanation I could think of. The repertoire was all things with which she is very familiar. They needed to rehearse more. It felt like they had rehearsed only enough to give a sense of anxiety. He was a young man. She should have been stern with him and told him to follow her.
If you don't know the music well enough to tell whether you are with it or not, you shouldn't be there in the first place.