Eyes don't exist without a central nervous system to process it
Eyes can't be called eyes if they are procesing images for some sort of "nerve network" as you are mentioning. In that case, then any piece of concave translucent material with a proportionally equidistand focus/foci can be considered an eye. That would be like saying the elbow came before the arm.
Would the jellyfish not fit the description by @The Real
The skyward gaze of one set of eyes belonging to box jellyfish provides evidence that these creatures -- which lack a conventional brain -- are capable of sophisticated behavior. New research has shown that one species of jellyfish uses one set of eyes to navigate and keep itself close to home.
"It is a surprise that a jellyfish -- an animal normally considered to be lacking both brain and advanced behavior -- is able to perform visually guided navigation, which is not a trivial behavioral task," said lead researcher Anders Garm of the University of Copenhagen. "This shows that the behavioral abilities of simple animals, like jellyfish, may be underestimated." [Image Gallery: Jellyfish Rule!]
Box jellyfish have 24 eyes of four different types, and two of them -- the upper and lower lens eyes -- can form images and resemble the eyes of vertebrates like humans. The other eyes are more primitive. It was already known that box jellyfish's vision allows them to perform simpler tasks, like responding to light and avoiding obstacles.