When i look at most stripped patterns I instantly green lines running perpendicular to them. I did some research and found out this is called the McCollough affect. However I have never stared at one the affect inducing images, and the green lines go away immediately when I look away, theres no after image.

i have visual snow/HPPD and get both positive and negative after images very easily. I think it maybe related to this, but have not found anyone with VS experience this. Years ago when my VS first started i got a brain MRI and sent to a opthamologist who found nothing.