Mom's eyesight seems to vary from day to day. One day she is OK with her prescription glasses, next day she is frustrated. Any advice?

Does she live in a dry climate? Perhaps she gets dry eye. That happens to me, living in a dry climate where my eyes are okay one day and the next everything's blurry. Perhaps check with her eye doc to find out the best eyedrops for her, and encourage her to use it daily.

I also keep my old readers. Some days the stronger powered glasses work better than the older weaker powered glasses. Does she have her old glasses? Perhaps one set works better than another on certain days.