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 I had surgery on my eyes this past summer to finally correct a long-lasting case of exotropia (lazy eye).  All my life I had convinced myself that if I just concentrated on not letting my eyes "wander," I could fix the problem and avoid surgery.  Imagine my surprise when the optometrist revealed that the problem had nothing to do with the eye muscles and everything to do with my brain -- especially when the surgery involved tightening the muscles behind my eyes.  Apparently, the brain sends a signal to the eye to wander.  As soon as the eye wanders, it goes blind; in other words, if my eye wandered up and left, I still wouldn't be able to see anything in my upper left visual field with that eye.  To correct the problem, they could, theoretically, fix that misguided brain signal -- but the easier fix, naturally, is with the eye muscles.  So the brain signal is still coming, but the muscles are tightened, restricting wandering.

When one of our eyes goes "blind" like mine did, our depth perception is compromised (Try going through a day with one eye closed).  Why, then, was I able to grab things in front of me, even when my eye "wandered"?  Why was I allowed to drive?  Where is the control center for our depth perception?