From the time I was 18 until I was about 36, I did the majority of my big game hunting and centerfire practice shooting with an old Griffin and Howe Springfield equipped with a Lyman M-48 peep sight. Back then, both front bead and target were seen with crystal clarity. That ain't so with the Williams 5D on my Marlin 336 in the here and now, as either the bead or the target will be a little fuzzy and out of focus. Still, with the peep, I simply look through it and don't fret too much over a little fuzzyness in the sight picture.
Different story when shooting my revolver. At the range, I focus on the front sight and let the black circle of the target be as fuzzy and blurry as it wants to be. I can still shoot 290+/300 today, just as I did during my law enforcment career 20 years ago. The difference is that the target isn't as sharp to me as it used to be.
Peeps are relatively cheap, so if you try one and don't like it, you aren't out a bunch of money. I don't have perfect visual accutiy, but the peep still works well enough for me.
JP