Not CCSVI specific. I can not remember it's name right now (OCT maybe...yeah), but there is that optical test where they measure the thickness of your retina. I think it was shown to have some correlation with MRI results (ie "disease progression"), but a lot quicker and simpler. I had one done, and it really is MUCH simpler than MRI.
I also have never had ON, and actually have very good eye sight (no glasses), but the test did show some thinning areas in my retina.