It is hard to beat an aperture rear sight. They have kept me in the iron sights game, which I much prefer. They obviously are ideal on your double gun.

I have found that, as my eyes change, adding a +0.5 diopter lens for my shooting glasses helps even more in combination with the aperture sight. They are a little bit hard to find, but they are available for just a few bucks on Amazon with a bit of digging.