The first time I had one was in the "enclosed" MRI and the technician offered me a facecloth to cover my eyes. It really helped.
I had another MRI about 2 months ago in the new "open" MRI...which isn't really "open"...but does have a bigger opening. They didn't offer a facecloth and I didn't ask...I just kept my eyes closed and concentrated on my breathing. Making sure it was deep and even instead of shallow and fast. It was over before I knew it.