Most likely, you remembered what you perceived and understood, NOT what you saw. Go back and look for errors. Cameras reveal that the eyes of the reader stop intermittently as they move rapidly across a line. Print is only seen clearly when the eye fixate . What seems like visual continuity, then is provided by the brain, not the eyes.
Eyes also move backward on occasion.
The natural return sweep can also be seen. As a child gains skill in silent reading, fixations and regressions decrease in number and the eyes take less time to fixate. Mature silent reading is characterized by a minimal number of fixations and regressions, and by fixations that are very brief. The eyes yield to this lower pace. Fixation is longer.