The Harvard-trained palaeontologist Kurt Wise who studied under Gould interestingly makes the following claim that the schizochroal eye is good evidence for design because it exceeds the needs of the trilobite. Although I am inclined to assume he is correct, I do not know much about trilobites, and as a layman, I would think a better optical system is always better, but maybe there is no selective pressure in the trilobite's environment to explain this, as Wise claims.
The design of the schizochroal eye makes it unique among eyes; perhaps even to the point of being the best optical system known in the biological world. This design, in fact, seems to far exceed the needs of the trilobite. The origin of the design of the schizochroal eye is not understood by means of any known natural cause. Rather, it is best understood as being due to an intelligent (design-creating) cause, through a process involving remarkably high manipulative ability.
http://www.answersingenesis.org/docs/313.asp