I am familiar with flicker fusion, and many of the theories that account for it, as well as Purkyně's pionering work in these matters. But my sense of it is that it is a neurological phenomenon, the brain and the eye working together (happy to be corrected, though).

So I still conclude that light falls continunously on the retina, and is continuously processed. But, I will further nuance this, by stating that, in the very contrived and special circumstance of very similar images in sequence, representing motion, appearing in rapid progression at a certain controlled rate, are spontaneously perceived as motion (an illusion) by the brain and the eye working together to make sense of a visual phenomenon that does not exist in nature, but only under artificial circumstances.