Aperture sights work very well to sharpen the target image especially with older eyes. Thankfully I'm far sighted and can still focus on my barrel sights pretty well. Just don't ask me to read the menu without reading glasses.
https://www.muzzleloadingforum.com/threads/folding-peep-sight.145105/
https://www.muzzleloadingforum.com/threads/folding-peep-sight.145105/