The way senses are processed is almost unbelievable.

When your eyesight is partially damaged (by a laser, for example), your brain will fill in the spots, so you won't even realise there's a problem until it's too late (too much damage to cover up).
As the above stated, there's a blind spot (although I don't think it's smack in the middle) - there are tests online you can try to 'see' it.
Your sight also automatically enhances objects it thinks are important, and will predict movementsand patterns, e.g. a baseball you're trying to hit.
There's also no colour in peripheral vision, although the brain does colour it in.