() genes play an important role in the proper formation of retinal cells in vertebrates, in particular horizontal, retinal ganglion and amacrine cells. However, it is not fully known how the unique and combined action of multiple gene copies leads to the induction and differentiation of specific retinal cell types. To gain new insights on how genes influence retina formation, we have examined the developmental role of , and genes during eye formation in the non-mammalian vertebrate zebrafish . By using single and multiple morpholino knockdown of three zebrafish genes we provide evidence for the independent and redundant role of each gene in the formation of photoreceptors and other retinal tissues. Through comparison of genetic pathways in photoreceptor differentiation among chordates we demonstrate their mechanism of action through a series of conserved target genes involved in neural transmission.