Just because they react to these objects doesn't mean they can see them clearly. It's just physics based on the eye and lens dimensions. With human eyes that threshold is about 10 cm, and if you try seeing objects closer than that you can still very much track and identify them, but they are blurry nonetheless. Maybe cat brains are also better at compensating for it, that part we can't really know, but they are most adapted to be ambush predators that don't really need to see things up close once they lock on and pounce.