Who sees better ?

Sometimes my brain is definitely out of the loop. We did a reading in Italian class with a fill in the blank and here is where I tripped up with my critical thinking.

"Gino and Dino are twins. Gino wears glasses. Dino doesn't wear glasses. Gino sees better than/worse than Dino."

"Gino sees better," I said.

"No," the teacher responded, "Gino wears glasses."

"That's right. He wears glasses and Dino doesn't. They're twins. So the one who wears glasses has corrected vision and sees better. The one who doesn't wear glasses just walks around with impaired vision."

"No, I think the sentence means one needs glasses and one does not."

"Oh!" It seems so obvious AFTER THE FACT.