The eye was cited by many as a "perfect" organ. how is the eye actually imperfect, and why are these imperfections important to understanding its evolution?

 If the eye were perfect, all organisms with eyes would distinguish the same colors, there wouldn't be any issues with vision, and the placement of the eye would be the same for all. These imperfections are important because they can provide answers to evolutionary traits. For example; Deer have eyes on the sides of their heads. This is due to their need to see all around them, in order to watch out for danger.