Glasses are very important to protect your eyes from flying debris.
I wear prescription glasses--Tifosi wraparound cycling glasses (I think the model name is Alpine or Alpe). They work great.
I am blind in my left eye, so there's no peripheral vision there anyways. I use a rearview mirror on my left handlebar (by Ortleib, $20). It's very helpful. I never wear headphones because I depend on my hearing. If I do have to look behind me, I have to swivel to the right.
In my opinion, protecting your vision is really, really important, and sometimes we take it for granted. With only one eye, I don't have a backup, so I'm just extra careful.