You can also have your prescription for your master (sights eye) ground to see the front sight clearly, the rear sight slightly less clear, and the other eye prescription ground so you can see the target clearly. If you make both lenses bifocals, you can have the lower (non-sight line portion) ground for clear vision while adjusting screws, writing, close work, etc. Find an eye doctor who shoots your type of shooting sport and they will do the right things. Costco optometrists may need serious coaching and several sets of lenses having to be redone to get this concept.