Somebody tested you in the past and you got a pair that works fine. You still have the numbers from last time and you want another pair.

How do you know if your current pair is "working fine", though? I've been wearing glasses for 20+ years and I'm not confident/aware/knowledgeable enough to know if my current prescription is, "working fine".

So there’s some need to take a vision test periodically. You actually don’t need a professional for this, you can print an eye chart off the internet.

Even so, the need to get your vision tested is often not related to the need to replace your glasses because they broke or you lost them.