Yes, there is and some local eye doctors don't like to respect it. So,
I'm going to share the URL:
https://www.ftc.gov/news-events/press-releases/2020/12/ftc-sends-28-warning-letters-regarding-agencys-eyeglass-rule
You won't care about the letter portion of it but the rule itself is
spelled out in the second paragraph.
Diane