For those of us with "mature" eyes, focusing on both sights and the target hasn't worked in years I use a red dot. You can find one for less than $100. Keep both eyes open, when the dot gets to your intended point of impact touch the trigger. I have installed on three home defence rifles for family/friends after they try mine and have one more to go.
I've got a Truglo red dot sight mounted on my 45. They're inexpensive and work good too. Truglo is a good company to deal with as well. My first one that I purchased at a gun show died. I assumed the battery was dead so I bought new ones and replaced it. Still no joy so I called Truglo in Texas. They told me to send it in and within 2 weeks there was a brand new one sitting on my doorstep. I like companies that stand behind their products. Mike