Peep sights act as what's called a pin hole lense, and actually improve your vision. The smaller the peep, the more effective the lense and the greater the depth of field (depth of field is the range of distances which are in focus on your retina - the photosensitive surface inside your eye) it provides.... but since smaller peeps let less light get to your eye, they aren't very effective in low light. However, even a ghost ring peep provides a small lense effect. The lense effect is a GREAT thing for us old guys.
The best way to use a peep is to mount it as close as possible to your eye, and to focus only on the front sight and the target. Your brain will subconsciously align your eye with the center of the peep, so there is no need to see it at all. That also helps us old timers because the closest thing we have to pay attention to is our front sight, and even our old tired eyes have enough depth of field to develop simultaneous sharp images of the front sight and the target.
Until red dot sights came along, ghost ring peep sights were the fastest on target of all sights, and that's why the military used them until red dot sights (some of them with integrated night vision devices) became sufficiently compact and rugged for military use - which is a very recent development. A ghost ring peep is as fast on target as a red dot sight, but it lacks the relative parallax freedom of red dots.
Skinner peeps are really low profile on a rifle, they are as rugged as you can get, they are fully adjustable, they offer a wide range of easily interchanged aperature sizes, and they look good on rifles. My Henry .45-70 lever-action carbine (home defense, timber hunting, and grizz protection) rifle wears one, and my Renegade will wear one as soon as I get it mounted. I could screw the Skinner peep into the mounting holes for the Renegade's stock rear sight, but I'm going to have the Renegade drilled and tapped to mount the Skinner peep with rear of the sight aligned with back of the breech plug so that it is very close to my eye.