I recently bought an old Diana 24 with open sights and having got hooked on using my other springers with peep sights found this quite challenging vision wise. I wear varifocals and found the open sights much harder to use than the Williams peep sights I use on other rifles.
The problem lies in the need to focus on the two elements of the open sights plus then aligning them with the target. With the peep sights you ignore the rear sight as it is there literally to peep through and not focus on.
If you just cannot manage open sights I would recommend trying peep sights before giving up and using a scope exclusively. The Williams sight is great fun and not over expensive, other peep and diopter sights are available of course.
Jim