I really don't know. Is it when the frames get too small?
Most Helpful Girl
Either when my prescription changes or when I feel like the frames have gotten too outdated for me.
My prescription hasn't changed in a few years so I had the same pair for a while. Recently I got new ones though because I'm too old for the previous I had gotten when I was like 11. They were some little kiddish plastic frames that got way too small for my face. So it was definitely time for an upgrade.1