We will never see an eye evolve in the lab. Such a complex structure would take too many generations to develop. But that is unnecessary, since the basic concept has been observed in the lab with simpler mechanisms. If evolution works AT ALL, then it proves that it is the mechanism by which all species came about.
That's what scientists do, they set up experiments to test the principle from a simplified example.
This it is only speculation then, that this could happen. So science does not know if this eye could come from something that had no eye material at all. This is really point about this, science can't say that creation not possible. So then how can they take a side, in this question, if they have no proof or have never seen it done.
Evolution says that a complete fossil record would consist of lineages of organisms showing gradual change continuously over long periods of time. But Darwin himself said that, the number of intermediate (transitional) varieties, which have formerly existed, must be truly enormous. He was hoping that the fossil record would show that, because when he was alive there were no fossils that supported that. He was hoping they would be found at a later time. But they have not.
What I am saying is not new. Darwin thought about it. And saw it as a huge problem. And it still is.
Science does not know how life started or how evolution could get to what we see today, and in the fossil record.