Are non-prescription circle lenses illegal in the USA?

I don't necessarily plan on buying circle lenses*, yet. They are not prescription. I need them for a specific "costume", per say. Not to wear them everyday.
I plan to just buy one pair from pinkyparadise.com. Which seems to be a trusted site to most.
But someone had told me that if they are not prescription they possibly wont be allowed into the USA?
Which puts me off from buying them. But as of not thy are important to get.

* Circle lenses are contacts who's purpose is specifically for enlarging your eyes and changing the color, temporarily of course. (In other words, for cosmetic purposes.)

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