Like the OP'er, I ride a drop-bar road bike and I wear glasses. I'm also hearing impaired - mostly in my left ear - so, generally I can hear a nearby car and know to be extra cautious. However, I don't have a sense for what direction car noise is coming from. I've tried five different mirrors in the past three years. Of those, my all-around favorite is a Third-Eye bar-end mirror. It's cheap and cheerful, but the mirror quality is pretty good and it has an appropriate amount of curvature. It helps me spot cars when they're pretty far away (behind me) at just a glance. With it, I can judge overtaking cars' speed and distance quicker and more confidently.

I tried to like an EVT helmet mounted mirror for a year... but I could never get information from it quickly enough. I had to wait for my eyes to focus, and then think about what I was seeing. I think I would have the same problem with any eyeglass or helmet mounted mirror. On my commuter, which has bar-end shifters, I use a Blackburn mirror that straps onto the left-side brake hood. It's okay, but vibrates more than the Third-Eye bar-end. I didn't like the way the D+D Oberlauda mirror mounted. It always seemed in the way of my hands, and it didn't play nice with my bar tape. Also, the Third-Eye is larger and thus more functional than the expensive German mirror.