The vision thing is only part of it. I was having trouble keeping my front sight in focus and my scores were really falling off within the last few years. I now wear multifocal contacts that allow me to see my front sight pretty clearly and still see my target from a distance, so, I'm still good with iron sights. The biggest thing for me, especially being in law enforcement and carrying a defensive pistol everywhere I go either on duty or off, is being able to stay target focused. I am looking at the target the whole time instead of my focus going from target to front sight, target to front sight, target to front sight, etc. Again, a red dot isn't going to magically make someone an instant crack shot. In fact, if you have bad habits (trigger press, grip issues, etc) it will magnify those. You still have to do the fundamentals right or you'll never hit an intended target with anything.