A peep sight, aka, apeture sight, is the fastest and easiest rear sight to use and it works well for those who would use reading glasses since you only have to see at two distances and not three since you don't need to see the rear sight at all. And really you need to see at one since Hoppdoc has it right when he describes putting the front bead on the target. Your eye will automatically center in the apeture. Small apetures allow precision shooting but a big apeture allows you to see the whole of the target and is much, much quicker.

BTW, if you use a peep sight you nees to get rid of any standing blade or whatever since this will interfere with the eye's centering of the front sight in the apeture.

I use a peep sight on a lever action currently and if need be I'll do the same with DG rifles. So far my eyes are fine with express sights but I would switch if needed and never look back.

JPK