I wear contacts and use what is called monovision. I used to wear only one cantact and it was for reading. The other eye was fine. When you look down to read, the contact eye takes over; when you look out to a distance other than reading, the other eye takes over.
The Doc explained it like a TV channel selector. The eyes select what they're supposed to do automatically. I now wear both eyes with contacts, however, same principal. One is at 375 power, the other 125. The 125 is for distance, and 375 is for reading.
For me, it works fine for scopes, and just plain sighting. I have the extended wear contacts, and do not change them but once a month. Granted, this isn't for everyone.