Well Moleeyes, I'm not far behind you in years. Fixin to turn 63. Open sights is something I've messed with since I was 6years old and it seems to get more complicated the more I think I know about it. My rear sight is halfway down the barrel nowadays and I have a shooting lense for a Knobloch glass frame that I got an optometrist (who understands gunsights) to make for me. When I was a young man, up til my late 40's, I had 20/15 vision in both eyes. Since then, I've spent way more time trying to see sights properly than I ever wanted to. Since you are going back to a "through the sights" zero, my advice to you would be make sure you can see the front sight clearly and keep the rear notch as shallow as you can. Adjust the width of the notch so the front sight is in focus. Its not as important for the target to be in focus as it is the front sight. Good luck and good shootin.