Sorry if I was unclear. I wasn't trying to imply that it did or didn't directly involve the retina, just that it seemed suspiciously related to the arrangement

Sorry if I was unclear. I wasn't trying to imply that it did or didn't directly involve the retina, just that it seemed suspiciously related to the arrangement of receptors on the retina, and I was curious why. If you had a spreading pattern of bad data in VRAM, it's unlikely that the physical arrangement of the bits would map well to the current screen resolution and give a circle or box shape on screen, for example.