The "Intelligent Design" argument about the eye was long ago debunked. I think those who subscribe to it have largely stopped using the "What use is half an eye?" line of argument because it's so obviously a dumb question. Our eyes didn't evolve from half an eye; they evolved from less efficient, less sensitive eyes.

Scientists ran a mathematical model back in 1994. If you start with a light-sensing surface, allow it to change in small, random, biologically feasible way, and only retain those changes that make it more sensitive you get to a recognisable eyeball WITH a lens in about 400,000 generations. Which is (aha-aha) an evolutionary eye-blink!