I have seen the blood vessels in my eyes when I hit my head on a concrete ceiling jumping down some stairs, just for a split second. That was weird. It was like kind of watery-looking clear shapes of my blood vessels as soon as I hit my head.

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On another note, I have been practicing this technique more. I have been able to see a type of grid with my eyes open that I see sometimes, and usually make go away because it used to make me feel like I was crazy. It's more like an overlay which may or may not be a grid. The last time the overlay was kind of red and amorphous. I hope to turn this into a Heads Up Display in my waking life eventually.
I have been having a hard time trying to relax and practice because my cat keeps walking on me when I lie down.