The phenomenon was first described by Erdmann and Dodge in 1898,[1] when it was noticed during unrelated experiments that an observer could never see the motion of their own eyes.
The phenomenon is often used to help explain a temporal illusion by the name of chronostasis, which momentarily occurs following a rapid eye-movement.
[4] Within-saccade movement detection was proven and detailed in a paper by Richard Schweitzer and Martin Rolfs at Humboldt University in Berlin.
Supporting this idea, a significant reduction of the cortical signals retinotopically encoding stimuli briefly presented immediately before the execution of a saccade has been found as early as in primary visual cortex.
As a result, the pattern, which is normally invisible, briefly becomes stabilized on the retina, and consequently becomes visible.
This situation does not last long — since a saccade doesn't have a constant velocity, very soon the eye is moving either faster or slower than the track, and the blur reappears in a course of a millisecond.
Yet, that millisecond (or so) is long enough for a snapshot of the retinal image to be stored, and to enable its further processing.