Ahhh, it's not as simple as that. I have 20/20 vision, in fact when I had my last eye test I could see further down the chart than the optician who was standing twice as near to it...... BUT I can't see a thing through a viewfinder without a ton of minus adjustment dialed in.
I now have glasses with a small positive prescription. I'm still trying to get my head around how a + lens will help remove the need for - adjustment on the camera. The story goes that the - on the camera stimulates accommodation (techy term) in the muscles that control focusing. Using the + glasses will supposedly reduce the need to for this and allow me to look through the camera without the need for the minus adjustment.
Does it work?
Well, to tell the truth, I don't really know. I find that I can't see as well with the glasses on, especially at night and in low light so I don't wear them too often. Except when my daughter tells me off.
So..... In short, yes go to the optician again but it doesn't mean there is anything wrong with your vision, as such.