RUebel, the same thing was/is bothering me as well. As a kid I was crossed-eyed and had to undergo an eye surgery. After that I was OK. I also worry that I'm not just damaging my eyesight. Now I'm new to PR and am still practicing the focus thing but when I first tried to see the blip page I tried to hard and nothing happened. Then after relaxing I went with the exercise where you gaze at your own feet and bring the book into the visual field- BAM -there was the blip. After doing it a couple of times I was able to see the blip even when I gazed trough the center of the book and now I get it easily right after opening my eyes. The other thing is mantaining to see the blip when turning pages. That's when I'm worried that I simply cross and not diverge. But that's what I do when I loose the blip. I try to move on with the X-technique and see the white space and the corners of the book. At that point the blip page often comes back to me and I carry on with it. Even when I see the blip I tend to get the rest of the pages into the peripheral vision from time to time. It sort of helps me keep my eyes relaxed and that what Alex mentioned when he answered your post- it should feel relaxed. Now don't take my experience to seriously- I'm new to PR, only had the course for some 14 days and would like to see what Alex or other more experienced readers have to say to the way I do the focusing. Maybe it OK so but maybe I really simply cross eyes.
Ales