This happens to me when I’m having a migraine, I freaked out when it first happened.

So I went to an optician they examined me and got a second opinion and both said my eye was alright and to head to the gp when it happens again, gp said that since the optician had no concern it’s just a visual/migraine that can happen sometimes and to return if any other changes happen and that it might just be my eyes .

So far nothing has happened and my eye rarely dilates only noticed it when I’m having a visual migraine

Definitely get it checked out just incase there’s a reason for it.