Light-induced shifts in opsin gene expression in the four-eyed fish .

The development of the vertebrate eye is a complex process orchestrated by several conserved transcriptional and signaling regulators. Aside from partial or complete loss, examples of exceptional modifications to this intricate organ are scarce. The unique eye of the four-eyed fish is composed of duplicated corneas and pupils, as well as specialized retina regions associated with simultaneous aerial and aquatic vision.