Have you had a retinal angiogram?

And I wonder if you had your B12 measured? It should be at least 400pg/ml...don't accept "normal" as very low lab results still are reported as normal.

Low B12 will cause damage to the optic nerve. And this may not show up on MRIs.

This is our B12 thread explaining all the details.
http://neurotalk.psychcentral.com/thread85103.html

It is best to use methylcobalamin for your supplement and also to take on an empty stomach, for best absorption.

I am leaving Fri for a long vacation...so any questions you have, try to make them before Thurs night.

I had a blood clot in a vein in my retina, and lost some vision for about 6mos, but it came back. It was in the lower field on the outer corner...which means the vein that was blocked, was in the upper field. The tiny veins and arteries in the retina are prone to damage from clots or high blood pressure attacks.
Elevated homocysteine levels (due to low B12 status) also damage the circulation to the retina.