I don't know if this is due to pregnancy and nursing, but when my glasses broke the other day, I decided it was time to get contacts. (Mostly because ds knocks the glasses off my face every time I pick him up, which is how they broke to start with). I had heard that pregnancy and nursing affect vision, and I knew my vision seemed slightly blurry, so I figured either old age or pregnancy, but my vision was getting worse.
Anyhow, it turns out that the vision in my left eye has IMPROVED a lot, and the blurryness was caused by the glasses over correcting! I was so excited, I may have to get pregnant all over again, just to keep nursing longer!