You don't have to have vision problems to prefer the blue background.
Many people like it, find it easier on the eyes. However, it's not
optimal with all uses of Word.
I use it with my document that have Courier font (that's the font I use
for casual documents and drafts), while I use the white background with
documents that have other fonts. I have a toggle macro that allows me
to switch the background with one keystroke.
In fact, one of the reasons I chose Word over Word Perfect a few years
ago was Word's blue background option. Ironically it was WP that had
orginated that feature, but they gave it up, even as Word acquired it.
Larry