Here's a trick I'm working on at the range.
The problem is "old eyes" that can focus on one solitary point only! That makes open sights, even peep sights less than perfect.
I picked this up from one of our muzzle loading fans at the club. Since muzzle loaders absolutely are forbidden to use anything except open sights, I thought this may help..............particularly if you are wearing eye-glasses.
Place a strip of electricians tape over the glass lense- just enough to cover a small portion of the eye-glass lense where you view your sights through. Punch a small hole in the center of the tape so the eye looks through that spot when lined up with the sights. This in effect causes your depth of field to be extended so you can see the sights and the target in sharp focus. Experiment with different sized holes in the tape to find the best comprimise of depth of field and amount of light you let through.
Give it a try and let me know what you think. I know someone in the Albany NY region makes a clip-on sighting device with adjustable aperture that works on this principle.
Jim