It could be the vaxx has clotted visual parts of their brain..or even the optic nerve itself...but I'm more inclined to think it's in the brain itself.

It probably affects the "blind spot" of your eyeball where your optic nerve is and that causes people to maybe see something in their peripheral... I donno, maybe a dark area..dark blobs..or maybe even a bright light in that area.

It would look like something was behind you just out of your visual reach..so you keep turning to 'catch up' to it. Then the clot causes a stroke-like seizure.

If any of these people survived, it would be helpful to ask them what they actually saw before convulsing.