Recall that the technique is used to help you (1) focus and (2) expand your field of vision by helping you relax and change the perspective you have on the text.
If you vision is not relaxed during super reading and you are experiencing "tunnel vision" so to speak, here is what I'd recommend that you do.
Close your eyes and re-enter the accelerated learning state. Give yourself a positive command to relax your field of vision and soften your gaze.
In your mind's eye, visualize that when you open your eyes, you will be standing over your own right shoulder to Super Read. Imagine that you are hovering over your shoulder Experience what it feels like, smells like, sounds like, etc.
Then, open your eyes while "seeing" over your right shoulder.
Whenever you feel yourself slip, briefly imagine yourself stepping out of your own ody to stand up and read over your shoulder.
Try that. Maybe it will work.