 But just like the rest of their body, as their body develops, their visual system develops. And then at some point, yes, they do, if everything goes well and it goes according to plan, they have that 20-20 vision. If something happens, though, during that developmental process, say there's some type of vision disorder, some type of eye disease, that can impact that developmental process. And if it's not caught, and then that continues to the point to where that –