Next time you meet an evolutionist ask this question:
Would you please explain how random mutations over a long period of time could produce the visual system when the mutations that are supposed to give rise to it do not increase the survivability of the organism?
If you came to my garage when I was a teenager and found that I was rebuilding the engine on my car with the parts all over the floor, you might ask "let's take it out for a spin." I would have to say that I was not finished yet. Until everything was put together, the car is useless as are the individual parts. Lying all over the garage floor, they just get in my way. The only benefit they serve is that I know what purpose they will eventually serve once I get it all put back together. But in evolution, they cannot possibly know what direction they are heading. The random chance mutations have no direction or design. It is impossible for a transitional form on its way to being part of an irreducibly complex system to be of any benefit in an unguided, purposeless, material process.
This is what is know as the non-viability of transitional forms.