Has anyone had a child with this condition and it turned out to be nothing? I'm scared

Yesterday at my daughter's eye appointment, the dr noticed that there is swelling around the optic nerve. He said it's not too concerning but he has to refer her to the hospital for other tests like MRI and stuff.

He told me not to worry but then why refer her to the hospital if it's not too concerning?! Of course I will worry. Well anyways, I googled that and I shouldn't have..I am so scared. She I only 8 years old.